Clinical and Second-look Arthroscopic Results for Derotational Distal Femoral Osteotomy With Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation With Increased Femoral Anteversion: A Series of 102 Cases With a Minimum Clinical Follow-up of 2 Years.

BACKGROUND: Derotational distal femoral osteotomy (DDFO) has been used to treat patients with recurrent patellar dislocation (RPD) with increased femoral anteversion. However, no study has reported second-look arthroscopic findings in the patellofemoral joint after DDFO. PURPOSE: To report clinical and second-look arthroscopic outcomes for DDFO with combined medial patellofemoral ligament reconstruction (MPFL-R) in treating RPD with increased femoral anteversion. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From 2015 to 2019, 131 consecutive patients (144 knees) with RPD were treated with combined MPFL-R and DDFO. Patients with a femoral anteversion angle >30° and a minimum 2-year clinical follow-up period were included in the study. Three-dimensional computed tomography was performed to evaluate rotational deformities of the lower leg. Radiographic parameters presenting bony abnormalities associated with RPD were measured. Second-look arthroscopic evaluations were available for 86 knees to assess patellar tracking and chondral lesion changes. Moreover, clinical and radiologic outcomes were assessed pre- and postoperatively at a minimum 2 years. RESULTS: A total of 102 knees in 92 patients were included in the present study with a mean clinical follow-up of 4.1 years (range, 2.0-5.6 years). Mean ± SD femoral anteversion changed significantly from 34.7°± 7.5° preoperatively to 11.3°± 0.2° postoperatively (P < .001), and mean tibial tubercle-trochlear groove distance decreased significantly from 19.6 ± 3.5 mm preoperatively to 17.4 ± 3.2 mm postoperatively (P < .001). In the majority of knees, at the time of second-look arthroscopic assessment, chondral lesion status remained unchanged at the lateral patellar facet (96%) and trochlear groove (95%); in contrast, chondral damage at the medial patellar facet was aggravated in 9 cases (10%). All functional scores (Tegner, Lysholm, visual analog scale, and Kujala scores) improved significantly at final follow-up. None of the patients experienced redislocation or subluxation after surgery. CONCLUSION: Chondral lesions in the patellofemoral joint remained unchanged in the majority of cases in second-look arthroscopy after combined MPFL-R and DDFO. Moreover, high-grade trochlear dysplasia and arthroscopic residual patellar maltracking might be associated with cartilaginous deterioration at the medial patellar facet after surgery.

Predictors of Graft Failure After Primary Medial Patellofemoral Ligament Reconstruction.

Background: The tibiofemoral rotation angle has been found to be higher in patients with recurrent patellar dislocations (RPDs) than in healthy people; however, little is known about the clinical significance of this finding. Purpose: To determine whether an increased tibiofemoral rotation angle is associated with graft failure after primary medial patellofemoral ligament reconstruction (MPFL-R) and to investigate the role of the tibiofemoral rotation angle in predicting MPFL-R failure in patients with RPDs. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively analyzed the records of 632 consecutive patients with clinically diagnosed RPDs from 2011 to 2018. Postoperative stress radiography of the patellofemoral joint was performed to identify whether the graft failed. After a review, 33 patients who showed MPFL-R failure were allocated to the failure group. They were matched 1:2 to 66 participants who underwent successful MPFL-R (control group). The cutoff value and area under the curve (AUC) of the tibiofemoral rotation angle for predicting graft failure after primary MPFL-R were determined, and the risk factors for MPFL-R failure were assessed by multivariate logistic regression analysis. Results: The tibiofemoral rotation angle was significantly higher in the failure group than in the control group (16.4° ± 5.6° vs 6.4° ± 4.5°, respectively; P < .001). The cutoff value of the tibiofemoral rotation angle for predicting graft failure was 12.3° (sensitivity, 81.8%; specificity, 89.4%; AUC, 0.920). Overall, 3 risk factors for MPFL-R failure were determined: excessive tibiofemoral rotation (≥12.3°) (odds ratio [OR], 13.159 [95% CI, 2.469-70.139]; P = .003), a preoperative high-grade J-sign (OR, 7.674 [95% CI, 1.232-47.809]; P = .029), and a femoral tunnel malposition (OR, 6.976 [95% CI, 1.077-45.187]; P = .042). Conclusion: In this study, excessive tibiofemoral rotation, a preoperative high-grade J-sign, and a femoral tunnel malposition were identified as risk factors for graft failure after primary MPFL-R in patients with RPDs. More importantly, excessive tibiofemoral rotation ( ≥ 12.3°) may predict the failure of primary MPFL-R, which can help surgeons easily identify high-risk patients of MPFL-R failure before surgery.

Posterior tibial slope measurements based on the full-length tibial anatomic axis are significantly increased compared to those based on the half-length tibial anatomic axis.

PURPOSE: This study aimed to compare the difference in posterior tibial slope (PTS) measurements based on the full-length and half-length tibial anatomic axes of the same group of patients. It was hypothesized that the obtained PTS values would be affected by the length of tibia chosen during the measurements. METHODS: Full-length true lateral tibia radiographs were obtained for each patient who underwent anterior cruciate ligament reconstruction (ACLR) in our department. PTS measurements were obtained by measuring the angle between the full-length or half-length tibial anatomic axis and an average of the lateral and medial tibial plateau. The anatomic axis was defined as the center of the tibial diaphysis. The PTS measurements from the full-length and half-length true lateral tibia radiographs were obtained and compared. Additionally, the absolute difference and the relationship between the two PTS measurements were calculated and analyzed. RESULTS: A total of 200 ACL-injured patients were included in this study. The average PTS values using the anatomic axis were 15.9 ± 3.7° and 14.1 ± 3.7° on full-length and half-length true lateral tibial radiographs. There was a significant difference between the measurements with the full-length and half-length tibial radiographs (P < 0.01). Additionally, 49.5% (n = 99) of patients had ≥ 2.0° differences between the full-length and half-length anatomic axis PTS measurement techniques; meanwhile, a strong and significant linear relationship (r = 0.95; P < 0.001) was identified between the two PTS measurements. CONCLUSION: There were significant differences and linear relationships between PTS measurements that measured the anatomic axis from full-length and half-length true lateral tibia radiographs. Therefore, the obtained PTS values were strongly associated with the length of tibia chosen during the measurements. Surgeons should pay more attention to the measurement techniques and the tibial length when considering the role of PTS in ACL injury and ACLR failure. Knowledge of the association is very important for calculating potential closing wedge proximal tibial osteotomies to correct excessive PTS in the setting of ACLR failures. LEVEL OF EVIDENCE: IV.

Increased Posterior Tibial Slope Is Associated With Greater Risk of Graft Roof Impingement After Anatomic Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Increased posterior tibial slope (PTS) has been reported to be associated with irreducible anterior tibial subluxation in extension after anatomic anterior cruciate ligament (ACL) reconstruction (ACLR), which raises concerns about the greater risk of graft roof impingement (GRI) although the tibial tunnel is positioned anatomically. HYPOTHESIS: Increased PTS would be associated with greater risk of GRI after anatomic ACLR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Between January 2016 and December 2017, a total of 418 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary anatomic ACLR. Among them, 26 patients had ≥1 of the following features during the second-look arthroscopy: fractured/guillotined bundles at the tibial insertion or cyclops lesion. These patients were confirmed to have GRI and were allocated to the study group. They were also matched 1:2 to 52 control participants without GRI. PTS was measured on true lateral whole-leg radiographs. Intra-articular ACL graft signal intensity was evaluated on postoperative magnetic resonance imaging scans (mean, 32.8 months; range, 26-38 months) and divided into 3 grades (I, good; II, moderate; III, poor) based on degree of GRI. Moreover, anterior subluxation of the lateral compartment (ASLC) and medial compartment (ASMC) in extension relative to the femoral condyles were measured on postoperative magnetic resonance imaging scans and compared between the groups. In addition, predictors of GRI were evaluated using multivariate logistic regression analysis and included body mass index, PTS, pivot-shift test, KT-1000 side-to-side difference, and concomitant meniscal tears. RESULTS: PTS in the study group was significantly higher than that in control group (mean ± SD, 13.8°± 1.5° vs 9.5°± 1.8°; P < .05). In the study group (n = 26), patients with grade III (poor) graft signal intensity (n = 9) showed significantly higher PTS than those with grade II (moderate; n = 17) (16.4°± 1.7° vs 12.4°± 1.3°; P < .05). Moreover, the mean postoperative ASLC and ASMC in extension were significantly larger in the study group than the control group (ASLC, 4.1 ± 1.3 vs 0.8 ± 0.4 mm; ASMC, 4.3 ± 1.5 vs 0.9 ± 0.3 mm; P < .05). Furthermore, the abnormal degree of PTS (≥12°) was determined to be an independent risk factor associated with GRI after anatomic ACLR (odds ratio, 9.0 [95% CI, 3.7-30.2]; P < .001), whereas body mass index, grade of pivot-shift test, KT-1000 side-to-side difference, and concomitant meniscal tears were not. CONCLUSION: Increased PTS (≥12°) was associated with greater risk of GRI after anatomic ACLR. This may provide additional information for counseling patients with greater risk of GRI.

Slope-Reducing Tibial Osteotomy Combined With Primary Anterior Cruciate Ligament Reconstruction Produces Improved Knee Stability in Patients With Steep Posterior Tibial Slope, Excessive Anterior Tibial Subluxation in Extension, and Chronic Meniscal Posterior Horn Tears.

BACKGROUND: Steep posterior tibial slope (PTS; >13°), excessive anterior tibial subluxation (ATS) in extension (>10 mm), and meniscus posterior horn tears (MPHTs) have been identified to be associated with primary anterior cruciate ligament (ACL) reconstruction (ACLR) failure. Recent studies have reported that steep PTS is directly correlated with excessive ATS in extension and concomitant MPHTs, especially for those patients with chronic (>6 months) ACL deficiency. There is increasing biomechanical evidence that slope-reducing tibial osteotomy decreases ATS in extension and protects the ACL graft. HYPOTHESIS: Slope-reducing tibial osteotomy combined with primary ACLR is effective for producing improved knee stability in patients with steep PTS (>13°), excessive ATS in extension (>10 mm), and concomitant chronic MPHTs (>6 months). STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between June 2016 and January 2018, 18 patients with ACL injuries who had steep PTS (>13°), excessive ATS in extension (>10 mm), and concomitant chronic MPHTs (>6 months) underwent slope-reducing tibial osteotomy combined with primary ACLR. The PTS and anterior subluxation of the lateral and medial compartment (ASLC and ASMC) in extension before and after the index procedures were regarded as primary clinical outcomes. Moreover, Lysholm score, Tegner activity score, International Knee Documentation Committee (IKDC) objective grade, pivot-shift test, and KT-1000 side-to-side difference were evaluated preoperatively and at the minimum 2-year follow-up visit. RESULTS: The mean PTS was 18.5° (range, 17°-20°) preoperatively and 8.1° (range, 7°-9°) postoperatively (P < .01). The mean ASLC and ASMC in extension were 12.1 mm and 11.9 mm preoperatively, which reduced to 1.0 mm and 1.5 mm at the last follow-up visit (P < .05). In addition, all of the following showed significant improvements (pre- vs postoperatively): mean Lysholm score (46.5 vs 89.5; P < .05), mean Tegner activity score (5.7 vs 7.3; P < .05), IKDC objective grading results (18 grade D vs 14 grade A and 4 grade B; P < .05), pivot-shift tests (15 grade 2+ and 3 grade 3+ vs 18 grade 0; P < .01), and KT-1000 side-to-side difference (13.0 mm vs 1.6 mm; P < .01). Moreover, no graft reruptures were found at the final follow-up visit. CONCLUSION: In this study, slope-reducing tibial osteotomy combined with primary ACLR effectively improved knee stability in patients with steep PTS (>13°), excessive ATS in extension (>10 mm), and concomitant chronic MPHTs (>6 months).

Steep Posterior Tibial Slope and Excessive Anterior Tibial Translation Are Predictive Risk Factors of Primary Anterior Cruciate Ligament Reconstruction Failure: A Case-Control Study With Prospectively Collected Data.

BACKGROUND: Steep posterior tibial slope (PTS) and excessive anterior tibial translation (ATT) have been identified as important anatomic risk factors for anterior cruciate ligament (ACL) injury, which have raised concerns about clinical outcomes after primary ACL reconstruction (ACLR). PURPOSE: To investigate anatomic risk factors of primary ACLR failure and to determine the cutoff values of PTS and ATT for predicting primary ACLR failure. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Between November 2015 and May 2017, a total of 215 consecutive patients with clinically diagnosed noncontact ACL injuries who underwent primary anatomic ACLR were retrospectively analyzed. Among them, 25 patients who showed complete discontinuity of ACL fibers on final follow-up magnetic resonance imaging scans were allocated into the failure group (study group). They were matched 1:2 to 50 control participants who showed clear and continuous ACL fibers on magnetic resonance imaging scans (control group). PTS and ATT were measured on preoperative weightbearing whole leg lateral radiographs and compared between the groups. The cutoff values of PTS and ATT for predicting primary ACLR failure were determined by the receiver operating characteristic curve. Moreover, predictors of primary ACLR failure were assessed by multivariate logistic regression analysis, including sex, age, body mass index, concomitant meniscal tears, degree of pivot-shift test, and KT-1000 arthrometer side-to-side difference, PTS, and ATT. RESULTS: PTS and ATT values in the study group were significantly higher than those in the control group (mean ± SD: PTS, 17.2°± 2.2° vs 14.4°± 2.8°; ATT, 8.3 ± 3.4 mm vs 4.1 ± 3.1 mm; P < .001). The cutoff values of PTS and ATT for predicting primary ACLR failure were 17° (sensitivity, 66.7%; specificity, 90.9%) and 6 mm (sensitivity, 87.5%; specificity, 79.5%), respectively. Additionally, PTS ≥17° (odds ratio, 15.6; 95% CI, 2.7-91.5; P = .002) and ATT ≥6 mm (odds ratio, 9.9; 95% CI, 1.9-51.4; P = .006) were determined to be risk factors of primary ACLR failure, whereas sex, age, body mass index, concomitant meniscal tears, degree of the pivot-shift test, and KT-1000 arthrometer side-to-side difference were not. CONCLUSION: In this study, PTS ≥17° and ATT ≥6 mm, as measured on weightbearing whole leg radiographs, were identified to be predictive risk factors of primary ACLR failure. This study adds to the existing knowledge about potential surgical indications of simultaneous slope-reducing high tibial osteotomy to mitigate the primary ACLR failure rate.

Development of heterotopic ossification after multiple-ligament reconstruction of the knee joint: Incidence and explanatory factor analysis.

BACKGROUND: The development of heterotopic ossification (HO) might nullify any benefit of multiple-ligament reconstruction of the knee joint. The purpose of this study was to investigate the incidence and the specific explanatory factors for the development of HO after multiple-ligament reconstruction of the knee joint. METHODS: From January 2011 to June 2016, 72 consecutive patients with knee dislocations received multiple-ligament reconstructions, of which 57 (79%) were available for a minimum follow up of 12 months and were included in this study. Anteroposterior (AP) and lateral radiographs were reviewed for all patients. This knee dislocation cohort was separated into two groups based on the presence or absence of HO for comparisons. In addition, the HO group was divided into three subgroups based on a modified quadrant grading system introduced by the senior author for further evaluation. Multivariate logistic regression analysis was then performed to identify specific explanatory factors predicting development of HO in patients after multiple-ligament reconstructions of the knee joint. RESULTS: Among the 72 consecutive patients, 57 (79%) were available for the clinical evaluations with an average period of 28.4 months (range, 12-51 months). Twenty-one patients (37%) showed radiological evidence of HO. The HO group (n = 21) showed significantly inferior results of knee flexion angle compared with the non-HO group (n = 36) (HO group vs. non-HO group: 124 ± 13° vs. 132 ± 5°; P<0.01). According to the quadrant grading system, there were seven patients with grade I, nine with grade II, and five with grade III HO. Subgroup analysis further revealed that higher HO grade would lead to lower knee flexion angle. In addition, multivariate regression analysis showed that concomitant posterior cruciate ligament reconstruction was the only independent explanatory factor predicting the development of HO after multiple-ligament reconstruction of the knee joint (P=0.018; odds ratio, 8.75; 95% confidence interval, 1.69-39.7). CONCLUSION: In this cohort of knee dislocations, the incidence of HO development following multiple-ligament reconstruction was 37%, with grade III HO showing the most inferior range of motion outcome. Moreover, concomitant posterior cruciate ligament reconstruction was the only independent predictor for the development of HO.

Excessive Preoperative Anterior Tibial Subluxation in Extension Is Associated With Inferior Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior tibial subluxation (ATS) in extension after anterior cruciate ligament (ACL) injury highlights an increased anterior position of the tibia relative to the femur. Recent studies demonstrated that subluxation is sometimes irreducible and the normal tibiofemoral relationship is not restored by ACL reconstruction (ACLR), which raises concerns regarding clinical outcomes after ACLR. HYPOTHESIS: Excessive preoperative ATS in extension is associated with inferior knee stability after anatomic ACLR. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: From March 2016 to January 2017, a total of 487 consecutive patients with clinically diagnosed noncontact ACL injuries who underwent primary anatomic ACLR were retrospectively analyzed. Of these patients, 430 met the criteria for inclusion in this study. Anterior subluxation of the lateral and medial compartments (ASLC and ASMC) in extension relative to the femoral condyles was measured on preoperative magnetic resonance imaging. Twenty patients (study group) who demonstrated excessive (>10 mm) ASLC and ASMC in extension were matched 1:2 to 40 participants (control group) who showed minimal or no (<3 mm) ASLC and ASMC in extension. The amount of ASLC and ASMC in extension relative to the femoral condyles at 2 years postoperatively was the primary outcome. Moreover, the Lysholm score, IKDC grade (International Knee Documentation Committee), and stability assessments (pivot-shift test and KT-1000 arthrometer side-to-side difference) were evaluated preoperatively and at the last follow-up visit. RESULTS: The preoperative mean ASLC and ASMC in extension of the study group were both significantly larger than those of the control group (study group vs control group: ASLC, 13.5 mm vs 1.2 mm; ASMC, 12.4 mm vs 1.0 mm; P < .05). Moreover, patients in the study group showed significantly larger posterior tibial slope than the patients in the control group (17.8°± 2.5° vs 9.5°± 1.5°; P < .05). At the final follow-up visit, the mean ASLC and ASMC of the study group were 8.1 mm and 7.3 mm, which were significantly larger than those of the control group (ASLC, 0.9 mm; ASMC, 0.7 mm; P < .05). In addition, the study group showed inferior knee stability when compared with the control group in terms of both the pivot-shift test (study group vs control group: 2 grade 2, 10 grade 1, and 8 grade 0 vs 1 grade 1 and 39 grade 0; P < .05) and the KT-1000 arthrometer side-to-side difference (study group vs control group: 4.4 ± 1.2 mm vs 1.5 ± 0.6 mm; P < .05). Furthermore, the study group showed significantly lower mean Lysholm score (study group vs control group: 80.3 ± 6.3 vs 93.3 ± 4.3, P < .05) and IKDC grading results (study group vs control group: 3 grade C, 16 grade B, and 1 grade A vs 3 grade B and 37 grade A; P < .05) as compared with the control group. CONCLUSION: In this short-term study, the excessive (>10 mm) preoperative ATS in extension after ACL injury was associated with inferior knee stability after anatomic ACLR.

Lateral Meniscus Posterior Root Lesion Influences Anterior Tibial Subluxation of the Lateral Compartment in Extension After Anterior Cruciate Ligament Injury.

BACKGROUND: The lateral meniscus posterior root (LMPR) lesion further decreases dynamic knee stability after anterior cruciate ligament (ACL) injury owing to the loss of the "wedge effect" maintained by the posterior horn of the lateral meniscus. However, the effect of LMPR lesions on the static tibiofemoral relationship in extension after ACL injuries is not determined. PURPOSE: To (1) determine the effect of LMPR lesions on anterior tibial subluxation of the lateral compartment (ATSLC) in extension in patients with ACL injuries and to (2) identify the LMPR-related factors associated with excessive ATSLC in extension. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Between January 2015 and December 2017, 405 consecutive patients with diagnosed ACL injuries who underwent primary ACL reconstructions were retrospectively reviewed. Among them, 45 patients with combined ACL injuries and LMPR lesions (ACL+LMPR group) and 51 patients with isolated ACL injuries (ACL group) were identified. Values of ATSLC in extension were measured on preoperative supine magnetic resonance imaging and classified into high grade (≥6 mm) and low grade (<6 mm). The mean ATSLC in extension and the proportion of patients with high-grade ATSLC in extension were compared between the groups by univariate analysis. In the ACL+LMPR group, predictors of high-grade ATSLC in extension-including age, sex, body mass index, affected side, cause of injury, period from injury (<12 or ≥12 weeks), LMPR lesion pattern (radial tear or root avulsion), and meniscofemoral ligament integrity (intact or impaired)-were assessed by univariate analysis and multivariate logistic regression analysis. RESULTS: The mean ATSLC in extension in the ACL+LMPR group was significantly greater than that in the ACL group (5.6 mm vs 3.1 mm; P = .001). The proportion of patients with high-grade ATSLC in extension in the ACL+LMPR group was also significantly larger than that in the ACL group (44.4% vs 15.7%; P = .002). In addition, the root avulsion (instead of radial tear) (odds ratio, 28.750; 95% CI, 2.344-352.549; P = .009) and the period from injury ≥12 weeks (odds ratio, 17.095; 95% CI, 1.207-242.101; P = .036) were determined to be the 2 independent predictors of high-grade ATSLC in extension. However, age, sex, body mass index, affected side, cause of injury, and meniscofemoral ligament integrity were not. CONCLUSION: After ACL injuries, concomitant LMPR lesion further increased ATSLC in extension. Chronic LMPR avulsion was associated with high-grade ATSLC in extension.

Tibial tubercle proximalization as quadriceps lengthening in treating severe habitual patellar dislocation in adults.

BACKGROUND: To describe a novel 'four-in-one' procedure - including tibial tubercle proximalization, extensive lateral release, tibial tubercle medialization, and medial patellofemoral ligament reconstruction - for treating severe habitual patellar dislocation (HPD) in adults, and to report its early clinical outcomes. METHODS: Thirteen patients (13 knees) with severe primary HPD received this procedure. Results of the physical examinations, including apprehension tests and patellar tracking throughout full range of motion, were recorded pre-operatively and at final follow-up. Radiological assessments included standard anteroposterior view, true lateral view at 30° knee flexion, axial views of the patellofemoral joint at both 30° and maximum angle of knee flexion, and computed tomography scans at full knee extension pre-operatively and at final follow-up. Subjective patellofemoral functions were evaluated with the Kujala functional score before the index procedure and at final follow-up visit. RESULTS: All 13 patients were followed for an average period of 35.5 months (range, 25-49). After the index 'four-in-one' procedure no patient reported reoccurrence of patellar dislocation at the final follow-up visit. Radiographically, there was a statistically significant improvement in the congruence angle from 75.2 ±â€¯16.3° pre-operatively to -7.2 ±â€¯5.4° postoperatively (P < 0.01) and in the lateral patellofemoral angle from -66.3 ±â€¯8.3° pre-operatively to 6.3 ±â€¯2.6° postoperatively (P < 0.01). The average pre-operative Kujala functional score was 41.4 and average postoperative score was 94.9 (P < 0.05). CONCLUSION: The novel 'four-in-one' procedure effectively treated HPD in adults with severe quadriceps contracture.

Tibial Tubercle Proximalization: A Novel Technique to Lengthen the Extensor Mechanism in Skeletally Mature Patients With Lateral Habitual Patellar Dislocations.

BACKGROUND: A habitual patellar dislocation (HPD) is a rare condition in skeletally mature patients, especially for those with severe quadriceps contracture. Until now, no study has reported the effectiveness of tibial tubercle proximalization to lengthen the extensor mechanism in treating severe HPDs in skeletally mature patients. PURPOSE: To describe a novel comprehensive procedure that includes tibial tubercle proximalization, extensive lateral release, tibial tubercle medialization, and medial patellofemoral ligament (MPFL) reconstruction in treating severe HPDs in skeletally mature patients and to report its early clinical outcomes. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From January 2014 to May 2016, a total of 43 consecutive patients (47 knees) with HPDs were surgically treated at a single institution and were retrospectively reviewed. Among them, 11 skeletally mature patients (11 knees) with severe primary HPDs underwent the index comprehensive procedure. Results of patellar tracking were recorded preoperatively and at the final follow-up. The radiological assessment included radiographs in standard anteroposterior, true lateral, and axial views and computed tomography scans at full knee extension before surgery and at the final follow-up. Subjective patellofemoral function was evaluated with the Kujala functional score before the index procedure and at the final follow-up visit. RESULTS: The 11 included patients were evaluated for a mean period of 34.9 months (range, 25-46 months). The mean knee flexion angle when the patella dislocated laterally was 25° (range, 10°-30°) preoperatively. Radiologically, there was a statistically significant improvement in the congruence angle, from 73.4° ± 17.0° preoperatively to -7.1° ± 5.8° postoperatively (P < .01) and in the lateral patellofemoral angle, from -65.6° ± 9.4° preoperatively to 6.1° ± 2.7° postoperatively (P < .01). The mean preoperative Kujala functional score was 42.9, and the mean postoperative Kujala functional score was 95.2 (P < .05). No patients reported a recurrence of patellar dislocation at the final follow-up visit. CONCLUSION: The novel comprehensive procedure, including tibial tubercle proximalization, extensive lateral release, tibial tubercle medialization, and MPFL reconstruction, effectively treated lateral HPDs in skeletally mature patients with severe quadriceps contracture.

Greater Static Anterior Tibial Subluxation of the Lateral Compartment After an Acute Anterior Cruciate Ligament Injury Is Associated With an Increased Posterior Tibial Slope.

BACKGROUND: Static anterior tibial subluxation of the lateral compartment after an anterior cruciate ligament (ACL) injury highlights an increased anterior position of the tibia relative to the femur. However, the precise cause of this phenomenon is not entirely clear. Recently, an increased posterior tibial slope (PTS) has been identified as an independent risk factor for noncontact ACL injuries. HYPOTHESIS: An increased PTS is associated with an increased anterior position of the lateral compartment of the tibia relative to the femur after acute ACL injuries. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: From March 2016 to March 2017, a total of 154 patients with clinically diagnosed noncontact ACL injuries who underwent primary ACL reconstruction were retrospectively analyzed. Static anterior subluxation of the lateral compartment relative to the lateral femoral condyle was measured on preoperative magnetic resonance imaging. Among them, 23 patients (study group) who demonstrated ≥6-mm anterior subluxation of the lateral compartment were matched in a 1:1 fashion to 23 control participants (control group), who showed <6-mm anterior subluxation of the lateral compartment. The PTS was measured on routinely available preoperative weightbearing lateral knee radiographs. Predictors of increased (≥6 mm) static anterior subluxation of the lateral compartment, including body mass index (BMI), PTS, injuries to the anterolateral ligament (ALL), and concomitant lateral meniscal lesions, were assessed by multivariable conditional logistic regression analysis. RESULTS: The mean PTS in the study group was 15.4°, which was significantly larger than that in the control group (8.8°) ( P < .001). In addition, an abnormal degree of PTS (≥10.0°) was determined to be an independent risk factor (odds ratio, 8.0 [95% CI, 2.7-29.2]; P < .001) associated with ≥6-mm anterior subluxation of the lateral compartment after acute ACL injuries. However, BMI, presence of concomitant lateral meniscal lesions, and presence of ALL ruptures were not. CONCLUSION: An increased PTS was identified to be an independent anatomic risk factor of increased (≥6 mm) anterior subluxation of the lateral compartment in acute noncontact ACL injuries. For patients with obviously increased anterior tibial subluxation of the lateral compartment after ACL injuries, the PTS should be measured.

Excessive lateral patellar translation on axial computed tomography indicates positive patellar J sign.

PURPOSE: The purpose of the study was to quantify the patellar J sign using traditional computed tomography (CT) scans. METHODS: Fifty-three patients (fifty-three knees) who suffered from recurrent patellar instability were included and analyzed. The patellar J sign was evaluated pre-operatively during active knee flexion and extension. It was defined as positive when there was obvious lateral patellar translation, and negative when there was not. The CT scans were performed in all patients with full knee extension; and the parameters including bisect offset index (BOI), patellar-trochlear-groove (PTG) distance, and patellar lateral tilt angle (PLTA) were measured on the axial slices. All the three parameters were compared between the J sign-positive group (study group) and the J sign-negative group (control group). In addition, the optimal thresholds of the three CT scan parameters for predicting the positive patellar J sign were determined with receiver operating characteristic (ROC) curves, and the diagnostic values were assessed by the area under the curve (AUC). RESULT: Among the fifty-three patients (fifty-three knees), thirty-seven (70%) showed obvious lateral patellar translation, which were defined as positive J sign (study group), and the remaining sixteen (30%) who showed no lateral translation were defined as negative J sign (control group). The mean values of the three CT parameters in the study group were all significantly larger compared to the control group, including BOI (121 ± 28% vs 88 ± 12%, P = 0.038), PTG distance (5.2 ± 6.6 mm vs - 4.4 ± 5.2 mm, P < 0.05), and PLTA (34.9 ± 10.5° vs 25.7 ± 3.4°, P = 0.001). Furthermore, the evaluation of ROC analysis showed that the AUC of BOI was the largest (AUC = 0.906) among the three parameters, and the optimal threshold of BOI to predict the positive patellar J sign was 97.5% (Sensitivity = 83.3%, Specificity = 87.5%). CONCLUSIONS: In this study, the prevalence of positive patellar J sign was 70%. The BOI measured from the axial CT scans of the knee joint can be used as an appropriate predictor to differentiate the positive J sign from the negative J sign, highlighting that the excessive lateral patellar translation on axial CT scan indicates positive patellar J sign. LEVEL OF EVIDENCE: IV.

Complete posterolateral meniscal root tear is associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament injuries.

PURPOSE: The purpose of this study was to investigate whether the complete posterolateral meniscal root tear (PLMRT) would be associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament (ACL) injuries. METHODS: From 2013 to 2015, a total of 1095 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary ACL reconstructions. Among them, 140 patients were arthroscopically verified to have concomitant PLMRTs. Application of the exclusion criteria finally left 74 patients who were finally allocated into high-grade pivot-shift (grades II and III) group (n = 51) and low-grade pivot-shift (grades 0 and I) group (n = 23) according to the results of pre-operative pivot-shift tests performed under anesthesia. Predictors of high-grade pivot-shift phenomenon, including degree of PLMRTs, integrity of posterior MFLs, status of lateral meniscal extrusion, age, sex, body mass index (BMI), and KT-1000 arthrometer side-to-side difference (SSD), were assessed by multivariable logistic regression analysis. RESULTS: The proportion of patients with complete PLMRT in high-grade pivot-shift group was significantly larger than that in low-grade pivot-shift group. In addition, complete PLMRT was significantly [odds ratio (OR) 4.044; 95% CI 1.125-14.534; P = 0.032] associated with high-grade pivot-shift phenomenon in noncontact ACL injury, especially for those with a time from injury to surgery of ≥12 weeks (OR 16.593; 95% CI 1.073-56.695; P = 0.014). However, no significant association was identified between neither the integrity of posterior MFLs nor the status of lateral meniscal extrusion and the high-grade pivot-shift phenomenon. CONCLUSION: Complete PLMRT is identified to be an independent risk factor of high-grade pivot-shift phenomenon in noncontact ACL injuries, particularly for those with a time from injury to surgery of ≥12 weeks. LEVEL OF EVIDENCE: IV.

Patients with high-grade pivot-shift phenomenon are associated with higher prevalence of anterolateral ligament injury after acute anterior cruciate ligament injuries.

PURPOSE: To compare the prevalence of concomitant anterolateral ligament (ALL) injury between patients with high-grade (grades II and III) pivot-shift and those with low-grade (grades 0 and I) pivot-shift phenomenon after acute anterior cruciate ligament (ACL) injuries. METHODS: Sixty-eight patients with an acute ACL injury who showed high-grade (grades II and III) pivot-shift phenomenon were enrolled as the study group. They were matched in a 1:1 fashion to another 68 ACL-injured control participants who showed low-grade (grades 0 and I) pivot-shift phenomenon during the same study period. Patients were matched by age, sex, and time from injury to surgery. A standardized pivot-shift test was performed under anesthesia for all the patients. Two blinded musculoskeletal radiologists reviewed the magnetic resonance imaging (MRI) scans for the presence of concomitant ALL injury. The grade of an ALL injury was divided into grade 0 (normal), grade I (sprain), grade II (partial tear), and grade III (complete tear). The prevalence and the grade of concomitant ALL injury were further compared between the study group and the control group. RESULTS: Overall, the prevalence of concomitant ALL injury in the study group (94.1%, 64/68) was significantly higher than that in the control group [60.3%, (41/68), P < 0.05]. Specifically, there were 49 patients (49/64, 76.6%) who showed grade II/III (partial/complete tear) MRI evidence of concomitant ALL injury, which was also significantly higher than that in the control group (12/41, 29.3%). CONCLUSIONS: Patients with high-grade pivot-shift phenomenon showed higher prevalence of concomitant ALL injury compared to those with low-grade pivot-shift phenomenon after acute ACL injuries. Careful assessment and proper treatment of this concomitant injury should be considered especially in knees with high-grade pivot-shift phenomenon. LEVEL OF EVIDENCE: III.

Is It Necessary to Repair Stable Ramp Lesions of the Medial Meniscus During Anterior Cruciate Ligament Reconstruction? A Prospective Randomized Controlled Trial.

BACKGROUND: A special type of meniscal lesion involving the peripheral attachment of the posterior horn of the medial meniscus (PHMM), termed a "ramp lesion," is commonly associated with an anterior cruciate ligament (ACL) injury. However, its treatment is still controversial. Recently, stable ramp lesions treated with abrasion and trephination alone have been shown to have good clinical outcomes after ACL reconstruction. HYPOTHESIS: Stable ramp lesions treated with abrasion and trephination alone during ACL reconstruction will result in similar clinical outcomes compared with those treated with surgical repair. STUDY DESIGN: Randomized controlled trial; Level of evidence, 2. METHODS: A prospective randomized controlled study was performed in 91 consecutive patients who had complete ACL injuries and concomitant stable ramp lesions of the medial meniscus. All patients were randomly allocated to 1 of 2 groups based on whether the stable ramp lesions were surgically repaired (study group; n = 50) or only abraded and trephined (control group; n = 41) during ACL reconstruction. All surgical procedures were performed by a single surgeon who was blinded to the functional assessment findings of the patients. The Lysholm score, subjective International Knee Documentation Committee (IKDC) score, and stability assessments (pivot-shift test, Lachman test, KT-1000 arthrometer side-to-side difference, and KT-1000 arthrometer differences of <3, 3-5, and >5 mm) were evaluated preoperatively and at the last follow-up. Moreover, magnetic resonance imaging (MRI) was used to evaluate the healing status of the ramp lesions. RESULTS: All consecutive patients who were screened for eligibility from August 2008 to April 2012 were enrolled and observed clinically. There were 40 patients in the study group and 33 patients in the control group who were observed for at least 2 years. At the final follow-up, there were no significant differences between the study group and the control group in terms of the mean Lysholm score (88.7 ± 4.8 vs 90.4 ± 5.8, respectively; P = .528), mean subjective IKDC score (83.6 ± 3.7 vs 82.2 ± 4.5, respectively; P = .594), pivot-shift test results ( P = .658), Lachman test results ( P = .525), KT-1000 arthrometer side-to-side difference (1.6 ± 1.2 vs 1.5 ± 1.1, respectively; P = .853), or KT-1000 arthrometer grading ( P = .738). Overall, for both groups (n = 73), 67 patients showed completely healed (38 study, 29 control), 3 showed partially healed (1 study, 2 control), and 3 showed nonhealed (1 study, 2 control) signals on follow-up MRI when evaluating the healing status of the ramp lesions. There was no significant difference regarding the healing status of the ramp lesions between the 2 groups ( P = .543). CONCLUSION: This prospective randomized controlled trial showed that, in terms of subjective scores, knee stability, and meniscal healing status, concomitant stable ramp lesions of the medial meniscus treated with abrasion and trephination alone during ACL reconstruction resulted in similar clinical outcomes compared with those treated with surgical repair.

What Role Does Low Bone Mineral Density Play in the "Killer Turn" Effect after Transtibial Posterior Cruciate Ligament Reconstruction?

OBJECTIVE: To explore the mechanism of the "killer turn", which is reported to be a reason for postoperative residual laxity after transtibial posterior cruciate ligament (PCL) reconstruction, in a low bone mineral density (BMD) condition. METHODS: A total of 80 skeletally mature female New Zealand white rabbits were included for biomechanical evaluation after transtibial PCL reconstructions. The subjects were equally divided into low BMD (n = 40) and control groups (n = 40). Rabbits in the low BMD group were treated with surgery and drug injection to establish an osteoporotic model. Rabbits in the control group received sham surgeries and no injection. All assignments were conducted randomly according to random numbers generated by a computer. All grafts were then subjected to biomechanical testing with an MTS model-858 Mini Bionix servohydraulic materials testing machine (MTS Systems, Minneapolis, Minnesota, USA). The experimental outcomes were the increment of total graft displacement, tunnel inlet enlargement, graft elongation, stiffness and failure load of the two groups, and the comparison between them. RESULTS: Among the 80 subjects, 1 subject of the low BMD group failed at the 30th cycle by proximal tibial fracture and 1 subject of the control group failed at the 20th cycle for the same reason. As a result, 39 subjects of the low BMD group and 39 subjects of the control group survived the cyclic loading test. Compared with the control group, the low BMD group demonstrated significantly larger total graft displacement ( P = 0.006) and tunnel inlet enlargement ( P = 0.041) than the control group. The number of subjects with less than 10% enlargement was significantly greater (57.1%) in the control group than in the low BMD group ( P = 0.004). In the load-to-failure test, 26 (66.7%) subjects in the low BMD group failed by proximal tibial fracture (around the tunnel), 6 (15.4%) at the mounting site, 5 (12.8%) at the fixation site, and only 2 (5.1%) failed at the "killer turn." In the control group, 20 (51.3%) failed at the "killer turn," 9 (23.1%) at the proximal tibia (around the tunnel), 5 (12.8%) at the mounting site, and 5 (12.8%) at the fixation site. There were significantly fewer failures (10.0%) at the "killer turn" ( P = 0.000) and 155.6% more for the para-tunnel fracture ( P = 0.000) in the low BMD group compared with the control group. CONCLUSIONS: The low BMD group demonstrated an inferior biomechanical outcome to the control group with the transtibial technique. With low BMD, the "killer turn" effect compromises the posterior tibial cortex by enlarging the tunnel inlet.

Increased Medial Meniscal Slope Is Associated With Greater Risk of Ramp Lesion in Noncontact Anterior Cruciate Ligament Injury.

BACKGROUND: A special type of meniscal lesion involving the peripheral attachment of the posterior horn of the medial meniscus (PHMM), termed ramp lesion, is commonly associated with anterior cruciate ligament (ACL) injury. However, no study has investigated its anatomic risk factors. Recently, increased meniscal slope has been identified as an independent anatomic risk factor for noncontact ACL injury. HYPOTHESIS: Increased medial meniscal slope (MMS) as measured on magnetic resonance imaging (MRI) will correlate with greater risk of concomitant ramp lesion in noncontact ACL injury. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: From January 2011 to December 2013, a total of 1012 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary ACL reconstructions. Among them, 160 patients were arthroscopically verified to have concomitant ramp lesions. Study exclusion criteria included partial ACL rupture, multiligamentous injury, associated medial/lateral meniscal lesions other than ramp lesion, skeletal immaturity, general joint laxity, severe malalignment of the lower extremity, history of knee surgery, lack of available preoperative MRI, and history of trauma to the proximal tibia. This left 53 patients in the study group (ACL + ramp group), who were matched in a 1:1 fashion to 53 control participants (isolated ACL group) who were arthroscopically verified to have isolated complete ACL injury during the same study period. Patients were matched by age, sex, and time from injury to surgery (TFI). Patients from the matched control group were selected by applying the same exclusion criteria as mentioned above. The MMS and medial posterior tibial slope (MPTS) were measured on the preoperative MRI in a blinded fashion. Predictors of ramp lesion, including MMS, MPTS, body mass index, pivot-shift test grade, and KT-1000 arthrometer side-to-side difference, were assessed by multivariable conditional logistic regression analysis. RESULTS: The mean MMS in the study group was 3.5°, which was significantly larger than that in the control group (2.0°; P < .001). In addition, increased MMS was significantly (odds ratio [OR], 5.180; 95% CI, 1.814-32.957; P < .001) associated with concomitant ramp lesion in noncontact ACL injury, especially for those with a TFI of ≥6 months (OR, 13.819; 95% CI, 2.251-49.585; P < .001). However, no significant association was identified between MPTS and concomitant ramp lesion. CONCLUSION: Increased MMS was identified to be an independent anatomic risk factor of concomitant ramp lesions in noncontact ACL injuries, particularly for those with a TFI ≥6 months. This may provide additional information for counseling patients who have increased MMS on the greater risk of secondary PHMM lesions if their ACL-deficient knee joints are not well stabilized initially.

Bone Contusions After Acute Noncontact Anterior Cruciate Ligament Injury Are Associated With Knee Joint Laxity, Concomitant Meniscal Lesions, and Anterolateral Ligament Abnormality.

PURPOSE: To examine the associated findings with bone contusions in patients after acute noncontact anterior cruciate ligament (ACL) injuries. METHODS: From January 1, 2011, to December 31, 2013, patients who underwent ACL reconstructions performed by the senior author (H.F.) were retrospectively analyzed. Presence and severity of bone contusion were determined from preoperative magnetic resonance images (MRIs) for each anatomic site including the lateral femoral condyle (LFC), lateral tibial plateau (LTP), medial femoral condyle (MFC), and medial tibial plateau (MTP). Multivariable logistic regression was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the associated findings (demographic data, preoperative physical examinations, concomitant meniscal lesions, intra-articular cartilage damages, and anterolateral ligament [ALL] abnormality) with bone contusions. Outcomes included the presence of bone contusions at each anatomic site (LFC, LTP, MFC, and MTP) and severity of lateral bone contusions (moderate/severe vs none/minimal). RESULTS: Among the 697 consecutive cases, 193 were finally selected. Prevalence of bone contusions seen on MRI was as follows: 60.6% LFC, 73.1% LTP, 6.2% MFC, and 21.2% MTP. Presence of bone contusions at LFC and LTP were significantly associated with high-grade (grade II and III) pivot-shift (ORLFC, 7.39; 95% CI, 1.99, 27.44; ORLTP, 2.52; 95% CI, 1.02, 6.24), concomitant lateral meniscal lesions (ORLFC, 3.23; 95% CI, 1.93, 11.31; ORLTP, 10.17; 95% CI, 1.86, 55.47), and ALL abnormality (ORLFC, 3.79; 95% CI, 1.46, 9.84; ORLTP, 4.47; 95% CI, 1.28, 15.58). However, none of the above associated findings was correlated with the presence of bone contusions at MFC and MTP. Furthermore, moderate/severe lateral bone contusions were still found to be significantly associated with high-grade (grade II and III) pivot-shift (ORLFC, 14.89; 95% CI, 2.71, 82.11; ORLTP, 6.76; 95% CI, 1.27, 36.06), concomitant lateral meniscal lesions (ORLFC, 17.34; 95% CI, 3.91, 76.87; ORLTP, 22.01; 95% CI, 5.08, 95.42), and ALL abnormality (ORLFC, 4.02; 95% CI, 1.33, 12.09; ORLTP, 2.57; 95% CI, 1.09, 6.04). CONCLUSIONS: For acute noncontact ACL injury, both the presence and the severity of lateral bone contusions are associated with high-grade (grade II and III) pivot-shift, concomitant lateral meniscal lesions, and ALL abnormality. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Prevalence of Lateral Meniscal Extrusion for Posterior Lateral Meniscal Root Lesion With and Without Concomitant Midbody Radial Tear in Anterior Cruciate Ligament Injury.

PURPOSE: To investigate the prevalence of lateral meniscal extrusion for patients with posterior lateral meniscal root lesions (PLMRLs) and for those with concomitant midbody radial tears (MRTs) in anterior cruciate ligament (ACL) injuries. METHODS: A database of consecutive patients undergoing primary ACL reconstruction between 2011 and 2013 was retrospectively reviewed to identify patients with isolated ACL injuries and those with associated PLMRLs. Patients with (1) unavailable preoperative magnetic resonance imaging scans, (2) other concomitant ligamentous injuries, (3) severe degeneration or malalignment, (4) infection or tumor, or (5) history of surgery on the injured side were excluded. For patients with associated PLMRLs (study group), degree of concomitant MRTs and status of meniscofemoral ligaments (MFLs) were verified arthroscopically. Prevalence of lateral meniscal extrusion was compared between (1) patients in the study group and those with isolated ACL injuries and between (2) those with and without concomitant MRTs in the study group. RESULTS: Of the 1,021 consecutive patients, 412 met the inclusion and exclusion criteria. Of those, 52 (5.1%) had an associated PLMRL (study group) and another 52 were randomly chosen from the 360 isolated ACL injuries as the control group. In the study group, 33 (63.5%) were arthroscopically verified to have concomitant MRTs. Prevalence of lateral meniscal extrusion was significantly higher (P < .0001) in the study group (30.8%; 95% confidence interval [CI], 18.3 to 43.3) than in the control group (1.9%; 95% CI, -1.8 to 5.6), whereas there was no significant difference (P = .758) between patients with (33.3%; 95% CI, 17.3 to 49.3) and without (26.3%; 95% CI, 6.5 to 46.1) concomitant MRTs in the study group. However, the 7 patients who showed either complete concomitant MRTs or absence of MFLs were all diagnosed to have lateral meniscal extrusion. CONCLUSIONS: The PLMRLs, identified in 5.1% of ACL injuries, appeared to result in lateral meniscal extrusion. Although the presence of a concomitant MRT did not further increase the prevalence of lateral meniscal extrusion in the setting of a PLMRL, surgical repair might still be necessary if a complete concomitant MRT or an absence of MFL was identified to restore normal meniscal functions. LEVEL OF EVIDENCE: Level III, prognostic case-control study.