Mid-flexion laxity could be identified with continuous flexion-arc gap assessment in patients with a large preoperative convergence angle.

PURPOSE: To analyze the incidence of intraoperative mid-flexion laxity using continuous flexion-arc gap assessment, risk factors for mid-flexion laxity, and clinical results in navigation-assisted total knee arthroplasty (TKA). METHODS: Ninety posterior-stabilized TKAs were performed under navigation guidance for patients with degenerative arthritis and varus deformity. Intraoperatively, the gap between the trial femoral component and insert was evaluated in the navigation system with continuous flexion-arc gap assessment. Each medial and lateral gap at flexion (90°) and extension (0°) were made to be less than 3 mm. Mid-flexion laxity was determined when the gap in the flexion range between 15° and 60° was 3 mm or more. The proportion of knees with mid-flexion laxity was investigated. The factors affecting mid-flexion laxity were identified in terms of demographics, preoperative convergence angle, and change in joint line height and posterior femoral offset. The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated. RESULTS: There were 31 cases (34.4%) of lateral mid-flexion laxity (average peak mid-flexion gap = 3.7 mm). The other 59 cases did not show mid-flexion laxity. The preoperative convergence angle was the only significant factor affecting lateral mid-flexion laxity (odds ratio = 1.466, p = 0.002). There were no significant differences in the clinical results between the groups with and without mid-flexion laxity. CONCLUSIONS: The continuous flexion-arc gap assessment was useful in evaluating mid-flexion laxity using navigation-assisted TKA. The preoperative convergence angle, reflecting soft-tissue laxity, can be a practical and simple radiographic finding for predicting lateral mid-flexion laxity. LEVEL OF EVIDENCE: IV.

Long-term outcomes were similar between hybrid and cemented TKAs performed on paired knees at a minimum 15 years of follow-up.

PURPOSE: To compare long-term clinical and radiographic results and survival rates between hybrid and cemented total knee arthroplasties (TKAs) performed on paired knees. METHODS: Seventy-two patients with hybrid and cemented TKAs performed on paired knees with NexGen® cruciate-retaining prostheses were retrospectively reviewed after a minimum 15 years of follow-up. Mean follow-up period was 17.5 years. Preoperative alignment deformity and range of motion (ROM) were not different between groups. The Knee Society score, Western Ontario and McMaster Universities Osteoarthritis Index, and ROM were evaluated. Radiographically, change in joint space width, component loosening, and osteolysis were evaluated. Implant survival rate was analyzed. RESULTS: There were no significant differences in clinical results between hybrid and cemented TKAs performed on paired knees of 72 patients at the last follow-up. No significant difference was observed in the change in joint space width between the two groups at the last follow-up (medial = 0.3 mm vs. 0.4 mm; lateral = 0.1 mm vs. 0.2 mm). One hybrid TKA showed tibial component loosening, for which revision was performed. There was femoral osteolysis in one hybrid and one cemented TKA, and tibial osteolysis in eight hybrid TKAs and seven cemented TKAs (n.s., respectively). The 20-year survival rate was 97.7% for hybrid TKAs and 100% for cemented TKAs (n.s.). CONCLUSION: The long-term outcomes were similar between hybrid and cemented TKAs performed on paired knees at a minimum 15 years of follow-up. The method of femoral component fixation did not have a significant effect on long-term TKA success. LEVEL OF EVIDENCE: III.

Long-term survival of fully cemented stem in re-revision total knee arthroplasty performed on femur with diaphyseal deformation due to implant loosening.

PURPOSE: The study aims to analyze long-term clinical and radiographic results, and survival of re-revision total knee arthroplasty (TKA) using fully cemented stems performed on femurs with diaphyseal deformation. METHODS: Thirty-seven re-revision TKAs using fully cemented stems performed in femoral diaphyseal deformations, characterized as diaphyseal canal enlargement and cortex deformation due to aseptic loosening of previously implanted stems, between 2003 and 2015 were retrospectively reviewed. The mean follow-up period was 10.0 years. Clinically, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were evaluated. Radiographically, mechanical axis (MA) and component positions were measured. Complications and survival rates were also analyzed. RESULTS: Clinically, the WOMAC significantly improved at final follow-up (61.2 vs 47.2, p < 0.001), but not the ROM (95.5 vs 102.5, p = 0.206). Radiographically, the MA and component positions were appropriate, with no changes in component positions from immediately post-operative to final follow-up, but with MA change from varus 2.9° to 3.7° (p = 0.020). Two cases (5.4%) with history of previous infections developed periprosthetic joint infection (PJI). Debridement with polyethylene insert exchange following antibiotic suppression were performed in those cases because of concern for difficult implant-cement removal. The five and ten year survival rates were 100% and 93.2%, respectively. CONCLUSION: Fully cemented stems are viable in providing long-term satisfactory survival after re-revision TKA in patients with femoral diaphyseal deformation. However, it should be used carefully for those with previous infections.

High Incidence of Tibial Component Loosening After Total Knee Arthroplasty Using Ceramic Titanium-Nitride-Coated Mobile Bearing Prosthesis in Moderate to Severe Varus Deformity: A Matched-Pair Study Between Ceramic-Coated Mobile Bearing and Fixed Bearing Prostheses.

BACKGROUND: We compared the incidence of aseptic component loosening and subsequent revision, and the survival rate between ceramic titanium-nitride-coated mobile bearing (MB) and fixed bearing total knee arthroplasties (TKAs) performed in patients with moderate to severe varus deformities. METHODS: In total, 200 TKAs using advanced coated system posterior stabilized prostheses in varus deformity of mechanical axis >8° between 2012 and 2016 were retrospectively reviewed. One hundred MB (ceramic-m group) and 100 fixed bearing (ceramic-f group) prostheses were included. The matches were made according to preoperative demographics, range of motion, and severity of deformity. The mean follow-up period was not different (ceramic-m vs ceramic-f = 4.8 vs 5.1 years; P = .104). The incidence of revision TKA due to aseptic component loosening and the survival rate (failure: revision due to aseptic loosening) was investigated. RESULTS: The incidence of revision TKA due to aseptic component loosening was 7 (7%) in the ceramic-m group and 1 (1%) in the ceramic-f group (P = .032). All cases of aseptic loosening occurred at the tibial component. The overall survival rate was 91.3% in the ceramic-m group and 98.9% in the ceramic-f group (P = .025). CONCLUSION: Considering the higher revision incidence and lower survival rate due to tibial component loosening, caution should be taken in tibial component fixation when using advanced coated system MB prosthesis in moderate to severe varus deformity. LEVEL OF EVIDENCE: III.

Mid-term clinical and radiological results do not differ between fixed- and mobile-bearing total knee arthroplasty using titanium-nitride-coated posterior-stabilized prostheses: a prospective randomized controlled trial.

PURPOSE: This study was performed to prospectively compare the clinical and radiographic results between mobile-bearing (MB) and fixed-bearing (FB) TKAs using ceramic titanium nitride (TiN)-coated prostheses. METHODS: Seventy MB and 70 FB TKAs using TiN-coated prostheses (ACS®) were prospectively evaluated. There were no differences in demographic characteristics between the two groups. Clinically, the Knee Society knee and function scores, WOMAC, and range of motion (ROM) were compared. Considering the possibility of a kinematic change in the polyethylene (PE) insert and a decrease in ROM following MB TKA, serial changes in the ROM were also compared. The thickness of the PE insert was compared according to the size of the femoral component. Radiographically, the alignment and positions of the components were compared. RESULTS: There were no differences between the two groups in clinical scores or ROM (n.s.). The maximum flexion increased from 133.5° ± 8.3° to 137.6° ± 5.5° across all time points in the MB group. The serial maximum flexion angles did not differ between the two groups over time (n.s.). The average thickness of the PE insert was greater in the MB group (12.0 ± 1.9 vs. 11.2 ± 1.6 mm, respectively, p = 0.008), especially when a large femoral component was used (12.7 ± 1.9 vs. 11.0 ± 1.5 mm, p = 0.005). The pre- and postoperative mechanical axes and positions of the components did not differ between the two groups (n.s.). CONCLUSIONS: TiN-coated MB TKA showed no significant advantage over FB TKA. The selection of bearing design would be clinically insignificant when using the TiN-coated TKA prosthesis. LEVEL OF EVIDENCE: II.

Long-term survival is similar between closed-wedge high tibial osteotomy and unicompartmental knee arthroplasty in patients with similar demographics.

PURPOSE: Long-term clinical and radiographic results and survival rates were compared between closed-wedge high tibial osteotomy (HTOs) and fixed-bearing unicompartmental knee arthroplasty (UKA) in patients with similar demographics. METHODS: Sixty HTOs and 50 UKAs completed between 1992 and 1998 were retrospectively reviewed. There were no significant differences in pre-operative demographics. The mean follow-up period was 10.7 ± 5.7 years for HTO and 12.0 ± 7.1 years for UKA (n.s.). The Knee Society knee and function scores, WOMAC, and range of motion (ROM) were investigated. The mechanical axis and femorotibial angle were evaluated. Kaplan-Meier survival analysis was performed (failure: revision to TKA) and the failure modes were investigated. RESULTS: Most of the clinical and radiographic results were not different at the last follow-up, except ROM; ROM was 135.3° ± 12.3° in HTO and 126.8° ± 13.3° in UKA (p = 0.005). The 5-, 10-, 15-, and 20-year survival rates were 100%, 91.0%, 63.4%, and 48.3% for closed-wedge HTO, respectively, and 90.5%, 87.1%, 70.8%, and 66.4% for UKA (n.s.). The survival rate was higher than that for UKA until 12 years post-operatively but was higher in UKAs thereafter, following a remarkable decrease in HTO. The most common failure mode was degenerative osteoarthritic progression of medial compartment in HTO and femoral component loosening in UKA. CONCLUSIONS: Long-term survival did not differ significantly between closed-wedge HTO and fixed-bearing UKA in patients with similar pre-operative demographics and knee conditions. The difference in post-operative ROM and failure mode should be considered when selecting a procedure. LEVEL OF EVIDENCE: III.

Comparison of Clinical Results and Injury Risk of Posterior Tibial Cortex Between Attune and Press Fit Condylar Sigma Knee Systems.

BACKGROUND: We compared clinical and radiographic results after total knee arthroplasty (TKA) using Attune and Press Fit Condylar Sigma, and investigated whether use of the current prosthesis increased injury risk to the tibial cortex in Asian patients. We also assessed whether a preoperative posterior tibial slope angle (PSA) is associated with the injury when using the current prosthesis. METHODS: The 300 TKAs with Attune (group A) were compared to the 300 TKAs with Press Fit Condylar Sigma (group B). Demographics were not different, except follow-up periods (24.8 vs 33.3 months, P < .001). The Western Ontario and McMaster Universities Index and range of motion were compared. A minimum distance between tibial component stem and posterior tibial cortex (mDSC) was compared. The correlation between preoperative PSA and mDSC was analyzed in group A. RESULTS: The postoperative Western Ontario and McMaster Universities Index and range of motion of group A were better than those of group B (17.7 vs 18.8, P = .004; 131.4° vs 129.0°, P = .008). The mDSC was shorter in group A (6.3 vs 7.0 mm, P < .001), which made up a higher proportion of the high-risk group for posterior tibial cortical injury with an mDSC of <4 mm (20.0% vs 10.7%, P = .002). A negative correlation was found between the preoperative PSA and mDSC in group A (r = -0.205, P < .001). CONCLUSION: The TKA using the current prosthesis provided more satisfactory results than the TKA using the previous prosthesis. However, the injury risk to the posterior tibial cortex increased in the knees with a large PSA when using the current prosthesis for Asian patients.

Medial Open-Wedge High Tibial Osteotomy May Adversely Affect the Patellofemoral Joint.

PURPOSE: To evaluate 2-stage arthroscopic findings of the patellofemoral joint before and after medial open-wedge high tibial osteotomy (HTO) and verify whether the patellofemoral joint would be influenced by medial open-wedge HTO. METHODS: We prospectively reviewed 114 cases of medial open-wedge HTO for the treatment of osteoarthritis with a varus knee. First-look arthroscopy was performed during HTO. The mean age at the time of HTO was 56.34 ± 5.4 years (range, 40-69 years). Second-look arthroscopy was performed concomitantly with plate removal at an average of 26.1 ± 6.0 months (range, 21.6-32.0 months) after HTO. We assessed the patellofemoral joint using the International Cartilage Repair Society (ICRS) grading system by first- and second-look arthroscopy and compared it before and after HTO. Postoperative anterior knee pain was also evaluated. RESULTS: Compared with first-look findings, second-look arthroscopic ICRS grading was changed as follows: In terms of the patella, 89 cases (78.1%) were not progressed whereas 25 cases (21.9%) were progressed. In terms of the femoral trochlea, 67 cases (58.8%) were not progressed whereas 47 cases (41.2%) were progressed. There was significant progression of the ICRS grade of the patella (P = .001) and femoral trochlea (P < .001) compared with first-look arthroscopic findings. The incidence of postoperative anterior knee pain was 11.4% (13 cases), and it was related to the ICRS grade of the patellofemoral joint at the time of second-look arthroscopy (P < .001 for patella and P < .001 for trochlea). CONCLUSIONS: This study showed that the patellofemoral joint might be adversely affected by medial open-wedge HTO. Although the incidence of postoperative anterior knee pain was low, it was clinically correlated with patellofemoral arthritis. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Comparison of patellofemoral outcomes after TKA using two prostheses with different patellofemoral design features.

PURPOSE: The purpose of the present study was to compare the clinical and radiographic results after TKA using two prostheses with different sagittal patellofemoral design features, including outcomes related to compatibility of the patellofemoral joint. METHODS: The clinical and radiographic results of 81 patients (100 knees) who underwent TKA using the specific prosthesis (group A) were compared with those in a control group who underwent TKA using the other prosthesis (group B). The presence of anterior knee joint pain, patellar crepitation, and patellar clunk syndrome was also checked. RESULTS: The function score and maximum flexion angle at the last follow-up were slightly better in group A than those in group B (92.0 ± 2.3 vs. 90.6 ± 4.2) (133.6° ± 8.4° vs. 129.6° ± 11.4°). Anterior knee pain was observed in 6 knees and patellar crepitation in four knees in group A. In group B, these symptoms were observed in 22 knees and 18 knees, respectively. There was no patellar clunk syndrome in either group. The alignment was corrected with satisfactory positioning of components. The patellar height remained unchanged after TKA in the two groups. The differences between preoperative and postoperative patellar tilt angle and patellar translation were small. CONCLUSION: When comparing the clinical and radiographic results after TKA using two prostheses with different sagittal patellofemoral design features, TKA using the specific prosthesis provided satisfactory results with less clinical symptoms related to the patellofemoral kinematics with TKA using the other prosthesis. LEVEL OF EVIDENCE: III.

A Comparison of the Medium-Term Results of Total Knee Arthroplasty Using Computer-Assisted and Conventional Techniques to Treat Patients With Extraarticular Femoral Deformities.

BACKGROUND: We compared the medium-term results of total knee arthroplasty (TKA) performed using computer-assisted surgery (CAS) and conventional techniques in patients with extraarticular femoral deformities. METHODS: The clinical and radiographic data of 40 knees (34 patients) with extraarticular femoral deformities that underwent consecutive CAS-TKA were compared with those of a control group that underwent conventional TKA (80 knees, 63 patients). No demographic data (in particular, the causes of the extraarticular deformities) differed between the two groups. The follow-up periods of the CAS and conventional TKA groups were 6.0 and 6.3 years, respectively. RESULTS: In the CAS group, the average knee score increased from 48.2 to 89.6 at the final follow-up (P < .001); the average function score increased from 51.4 to 91.4. The range of motion averaged 105.5° preoperatively and 123.3° postoperatively. No significant differences were found in the knee score, function score, or range of motion after TKA between the 2 groups. The average preoperative mechanical axes were 18.1° varus in both groups. The average postoperative mechanical axis was 1.4° varus in the CAS group and 3.3° varus in the conventional TKA group (P = .001). The proportion of postoperatively aligned knees was 77.5% in the CAS group and 32.5% in the conventional group (P < .001). CONCLUSION: Although the medium-term clinical results of TKA in extraarticular femoral deformities were satisfactory in both the CAS and conventional TKA groups, the former group exhibited more accurate postoperative coronal alignment. It was useful to employ navigation in patients with extraarticular deformities of various etiologies.

Comparison of mid-term results between conversion total knee arthroplasties following closed wedge high tibial osteotomy and primary total knee arthroplasties: A matched pair study including patellar symptom and position.

BACKGROUND: The purpose of this study was to compare mid-term clinical and radiographic results of conversion total knee arthroplasties (TKA) following a closed-wedge high tibial osteotomy (HTO) and primary TKAs. METHODS: A total of 32 conversion TKAs (29 patients) were compared with a matched control group of patients who had undergone primary TKA. The clinical results were evaluated using the Knee Society Knee and Function score, the Western Ontario and McMaster Universities score, patella score, and range of motion (ROM). The radiographic results were evaluated using femorotibial angle, mechanical axis (MA), the method employed by the American Knee Society, joint line height (JLH), the amount of tibial bone resection, and the Insall-Salvati ratio. The clinical and radiographic results of conversion TKAs were compared with primary TKAs. The thickness of the polyethylene insert was also compared. RESULTS: No significant differences were observed in the clinical scores or ROM between two groups. No significant differences were detected in femorotibial angle, MA, and position of the components between two groups. The amount of tibial bone resection and pre-operative JLH both were significantly lower in the conversion group than those in the control group, although postoperative JLH and pre and postoperative Insall-Salvati ratio did not differ between two groups. No significant difference in the thickness of the polyethylene insert was identified between two groups. CONCLUSIONS: The previous closed-wedge HTO itself had no detrimental effect on the mid-term outcome of the subsequent TKA, including patellar symptom and position. No significant differences in the postoperative joint line and patella height were detected between the conversion and primary TKA groups.

Computer-assisted navigation decreases the change in the tibial posterior slope angle after closed-wedge high tibial osteotomy.

PURPOSE: The purpose of the present study was to compare the change in tibial posterior slope angle (PSA) between patients treated via computer-assisted and conventional closed-wedge high tibial osteotomy (CWHTO). It was hypothesized that a decrease in the PSA would be less in the computer-assisted group than in the conventional group. METHODS: Data on a total of 75 computer-assisted CWHTOs (60 patients) and 75 conventional CWHTOs (49 patients) were retrospectively compared using matched pair analysis. The pre- and postoperative mechanical axis (MA) and the PSA were radiographically evaluated. The parallel angle was defined as the angle between the joint line and the osteotomy surface. The data were compared between the two groups. RESULTS: The postoperative radiographic MA averaged 1.3° ± 2.6° valgus in the computer-assisted group and 0.3° ± 3.1° varus in the conventional group. The change in PSA averaged -0.8° ± 0.9° in the computer-assisted group and -4.0° ± 2.2° in the conventional group. The parallel angle averaged 0.2° ± 3.0° in the computer-assisted group and 6.2° ± 5.3° in the conventional group. CONCLUSION: Computer-assisted CWHTO using four guide pins could avoid inadvertent change in the PSA. The navigation can be used in anticipation of decreasing the risk of change in the PSA in CWHTO, especially in patients whose preoperative PSA is small. The special attention should be paid to locate the hinge axis acutely and to make the parallel proximal and distal osteotomy surfaces during CWHTO. LEVEL OF EVIDENCE: III.

Intraoperative factors affecting conversion from cruciate retaining to cruciate substituting in total knee arthroplasty.

PURPOSE: The purpose of this study was to analyse the factors affecting the conversion from posterior cruciate ligament (PCL)-retaining (CR) to PCL-substituting (PS) prostheses during total knee arthroplasty (TKA). METHODS: A total of 920 TKAs, which had been preoperatively planned to undergo implantation of CR-type prostheses, were reviewed retrospectively. Of these, 83 knees (9.0 %) were converted intraoperatively to PS prostheses. The clinical and radiological factors of the non-converted (CR) and converted (PS) groups were compared. Clinically, age, gender, body mass index, angle of flexion contracture, size of the femoral component, and thickness of the polyethylene insert were compared between the CR and PS groups. Radiologically, the severity of the varus deformity and the posterior tibial slope angle (PSA) were compared between the CR and PS groups. RESULTS: No significant differences in age, gender, body mass index, range of motion, thickness of the polyethylene insert, or severity of varus deformity were identified. The average preoperative angle of flexion contracture was 5.9° ± 7.4° in the CR group and 8.1° ± 9.1° in the PS group (p = 0.002). The average preoperative PSA was 9.6° ± 4.0° in the CR group and 11.0° ± 5.0° in the PS group (p = 0.018). The conversion rates to a PS-type femoral component of size C, D, and E were 13.1, 7.0, and 6.3 %, respectively (p = 0.004). CONCLUSION: The conversion rate from CR- to PS-type prostheses was high in patients with severe flexion contracture, steep posterior slope, and a small femoral component size. These factors should be carefully considered for appropriate selection of prosthesis type. LEVEL OF EVIDENCE: IV.

Comparison of Midterm Clinical and Radiographic Results Between Total Knee Arthroplasties Using Medial Pivot and Posterior-Stabilized Prosthesis-A Matched Pair Analysis.

BACKGROUND: Despite the theoretical advantage of a knee design that can more reliably replicate the medial pivot (MP) of the natural knee, only a few clinical studies have compared the clinical results between the MP prosthesis and another design of prosthesis. We compared the midterm results of total knee arthroplasty (TKA) using an MP prosthesis vs a posterior-stabilized prosthesis via a matched-pair analysis; we included results related to patellofemoral joint symptoms. METHODS: The midterm clinical and radiographic results of 125 consecutive patients (150 knees) who underwent a TKA with the ADVANCE MP prosthesis were compared with those of a control group who had undergone a primary TKA with a posterior-stabilized prosthesis. RESULTS: Values of the Knee Society's Knee Scoring System, Western Ontario and McMaster Universities Osteoarthritis Index, and Kujala and Feller scoring systems, as well as the range of motion after TKA, did not significantly differ between the 2 groups. No differences in femorotibial angle and component position, including the patella component, were observed between the 2 groups. No significant differences in the change of patella tilt angle and the postoperative patellar translation were observed between the 2 groups. CONCLUSION: Patients with the MP prosthesis experienced satisfactory pain relief and a functional recovery, providing results similar to those of the posterior-stabilized prosthesis, including the resolution of patellofemoral joint symptoms.

Femorotibial relationship changes as the posture changes from patellae-forward stance to preferred toe-out stance.

BACKGROUND: Full-length standing anteroposterior radiograph is a standard protocol to evaluate the lower limb alignment in frontal plane. However, most people tend to stand or walk with feet pointing outward. The purpose of this study is to assess the femorotibial relationship as the posture changes from patellae-forward stance for the conventional technique of a full-length standing anteroposterior radiograph to a toe-out quiet stance using a fluoroscope. METHODS: Femoral and tibial rotation and femorotibial rotation were measured in 60 healthy lower limbs using fluoroscopy during postural change from patellae-forward stance to toe-out quiet stance. RESULTS: The average toe-out angle was 21.4°. The average femoral, tibial, and femorotibial rotations during postural change were 6.1°, 4.0°, and 2.1°, respectively (p = 0.000). The correlation coefficient for femoral and tibial rotation was 0.747 (p = 0.000). The correlation coefficient for femoral and femorotibial rotation was 0.670 (p = 0.000), and for tibial and femorotibial rotation was 0.006 (p = 0.962). The correlation between toe-out angle and femorotibial rotation was statistically significant (r (2) = 0.096, p = 0.016). The correlations between toe-out angle and femoral rotation, and between toe-out angle and tibial rotation were not statistically significant (r (2) = 0.047, p = 0.095, and r (2) = 0.000, p = 0.9, respectively). CONCLUSIONS: The subject's posture significantly affects the femorotibial relationship. When a subject changes posture from a patellae-forward stance to a toe-out quiet stance, the femur rotates internally on the tibia. LEVEL OF EVIDENCE: Diagnostic, level II.

Periprosthetic supracondylar femoral fractures above total knee arthroplasty: comparison of the locking and non-locking plating methods.

PURPOSE: The purpose of this study was to compare the results and complications of periprosthetic supracondylar femoral fracture treatment using locking or non-locking plates. METHODS: A locking compression plate was used in 14 patients, and a non-locking condylar buttress plate was used in 19 patients. There were no significant differences in the demographic data between the two groups. The primary healing rate and bone union time were compared. The Knee Society knee score and range of motion (ROM) were reviewed. The femorotibial angle and α and γ angles were measured using the Knee Society radiological evaluation method. The clinical and radiographic results, complications, and additional surgeries were compared between the two groups. RESULTS: Thirteen of 14 locking plating patients and 11 of 19 non-locking plating patients healed without any additional surgeries. There were no differences in the average bone union time, knee score, or ROM between the two groups. The alignment and position of the implants were better without a loss in the reduction angle of >3° in the locking plating group compared with the non-locking plating group. Locking plate fixation reduced the incidence of overall complications, non-union, malunion, loss of reduction, and additional surgeries compared with non-locking plate fixation. CONCLUSION: Fixation of periprosthetic supracondylar femoral fractures with a locking plate provided satisfactory results with a low risk of complications and additional surgeries compared with fixation with a non-locking plate. LEVEL OF EVIDENCE: III.

Similar Midterm Outcomes of Total Knee Arthroplasties with Anterior and Posterior Tibial Slopes Performed on Paired Knees at a Minimum Follow-up of 5 Years.

A small posterior tibial slope (PTS) is generally recommended in posterior stabilized (PS) total knee arthroplasty (TKA). An unwanted anterior tibial slope (ATS), which can affect postoperative results, may be created in PS TKA because of the inaccuracy of surgical instruments and techniques, as well as high interpatient variability. We compared midterm clinical and radiographic results of PS TKAs with ATS and PTS performed on paired knees using the same prosthesis. One-hundred-twenty-four patients who underwent TKAs with ATS and PTS on paired knees using ATTUNE posterior-stabilized prostheses were retrospectively reviewed after a minimum follow-up period of 5 years. The mean follow-up period was 5.4 years. The Knee Society Knee and Function scores, Western Ontario and McMaster Universities Osteoarthritis Index, Feller and Kujalar scores, and range of motion (ROM) were evaluated. The preferred TKA out of ATS and PTS was also investigated. The hip-knee-ankle angle, component positions, tibial slope, posterior femoral offset, Insall-Salvati ratio, and knee sagittal angle were measured by radiography. There were no significant differences in the clinical results, including ROM, between TKAs with ATS and PTS preoperatively and at the last follow-up. Regarding patient preference, 58 patients (46.8%) were satisfied with bilateral knees, 30 (24.2%) preferred knees with ATS, and 36 (29%) preferred knees with PTS. There was no significant difference in the rate of preference between TKAs with ATS and PTS (p = 0.539). Except for the postoperative tibial slope (-1.8 vs. 2.5 degrees, p < 0.001), there were also no significant differences in the radiographic results, including the knee sagittal angle, preoperatively and at the last follow-up. The midterm outcomes were similar between PS TKAs with ATS and PTS performed on paired knees at a minimum of 5 years of follow-up. Nonsevere ATS did not affect midterm outcomes in PS TKA with proper soft tissue balancing and the current prosthesis of improved design. However, a long-term follow-up study is required to confirm the safety of nonsevere ATS in PS TKA. LEVEL OF EVIDENCE:: III.

Survival analysis of microfracture in the osteoarthritic knee-minimum 10-year follow-up.

PURPOSE: The aim of this study was to evaluate the survival of microfractures in patients with degenerative osteoarthritic knees and to analyze the factors affecting length of time before total knee arthroplasty (TKA) is performed. METHODS: This study reviewed 134 knees in 124 patients in whom microfracture was performed and for whom a minimum of 10 years of follow-up data were available. Mean follow-up was 11.2 years. The survival rate was evaluated. Failure was defined as the need for TKA. Another definition of failure was substantial symptoms in a patient whose pain score during follow-up was lower than the preoperative pain score or <60. We evaluated factors affecting survival, including size of the cartilage defect and severity of the preoperative varus deformity. The mechanical axis percentage (MA%) was defined as the percentage by which the mechanical axis bisected the total width of the tibia. RESULTS: The survival rate was 88.8% at 5 years and 67.9% at 10 years. Fifty-one patients proceeded to TKA a mean of 6.8 years after microfracture, and 6 knees were categorized as clinical failures. Age, gender, body mass index (BMI), and presence of meniscus lesions did not affect the survival of microfractures. Survival of microfractures in patients with a cartilage defect on the medial femoral condyle <2 cm(2) in size was better than that of microfractures in patients with larger defects. Survival of microfractures in patients with MA% >25% was better than that of patients with MA% <25%. CONCLUSIONS: Among 134 knees, 51 knees (38.1%) proceeded to TKA a mean of 6.8 years after microfracture in this study, and 6 knees were categorized as clinical failures. The survival rate was 88.8% at 5 years and decreased over time to 67.9% at 10 years. When considering microfracture, surgeons must consider factors affecting survival, such as size of the cartilage defect and severity of the preoperative varus deformity. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Change in limb length after high tibial osteotomy using computer-assisted surgery: a comparative study of closed- and open-wedge osteotomies.

PURPOSE: Limb length changes were evaluated after closed- and open-wedge high tibial osteotomies (HTOs) using computer-assisted surgery. METHODS: A total of 78 closed- and 30 open-wedge HTOs were performed. The changes in limb length were evaluated on a navigation system and radiographs. The correction angle was defined as the difference between the pre and postoperative mechanical axis on the navigation system. The change in limb length with respect to the correction angle was analyzed. RESULTS: Following the closed-wedge HTOs, the mean changes in limb length based on the navigation system and radiographs were -1.3 ± 1.9 and -1.3 ± 10.7 mm, respectively, versus 6.2 ± 2.6 and 7.8 ± 2.9 mm after the open-wedge HTOs. The mean correction angle was 11.6 ± 3.2° for closed-wedge HTOs and 11.5 ± 1.9° for open-wedge HTOs. The correction angle did not affect the change in limb length after closed-wedge HTO, while the larger the correction angle required, the greater the increase in limb length after open-wedge HTO. CONCLUSIONS: The change in limb length was negligible after closed-wedge HTO, while the limb length was increased slightly after open-wedge HTO. The possibility of limb lengthening must be considered carefully when determining whom to perform open-wedge HTO on, especially when a large correction angle is required. LEVEL OF EVIDENCE: III.

Does the severity of preoperative varus deformity influence postoperative alignment in both conventional and computer-assisted total knee arthroplasty?

PURPOSE: The postoperative alignment was compared according to the severity of preoperative varus deformity in computer-assisted and conventional total knee arthroplasty (CAS-TKA). METHODS: The study reviewed 127 consecutive CAS-TKA and 236 conventional TKA, retrospectively. In CAS-TKA, 77 knees with a varus deformity ≤15.0° were classified in group CAS-A and 50 knees with a varus deformity >15.0° were classified in group CAS-B. In conventional groups, 204 knees with a varus deformity ≤15.0 were classified in group Conventional-A and 32 knees with a varus deformity >15.0° were classified in group Conventional-B. The postoperative mechanical axis (MA) was compared among groups CAS-A, CAS-B, Conventional-A and Conventional-B. RESULTS: The average postoperative MA was 0.7° varus in group CAS-A, 2.8° varus in group CAS-B, 1.1° varus in group Conventional-A and 3.2° varus in group Conventional-B (p < 0.001). The postoperative MA was within 3° in 81.8, 62.0, 58.8 and 37.5 % of group CAS-A, CAS-B, Conventional-A and Conventional-B, respectively. CONCLUSIONS: The severity of preoperative varus deformity influences postoperative alignment despite using CAS. More careful correction of the alignment is required, especially in TKA performed on patients with a greater varus deformity. LEVEL OF EVIDENCE: III.