Incidence of and risk factors for deep vein thrombosis in patients undergoing osteotomies around the knee: comparative analysis of different osteotomy types.

PURPOSE: To examine the incidence of and risk factors for deep vein thrombosis (DVT) among different types of osteotomies around the knee. It was hypothesized that DVT would be detected at a substantial rate after the osteotomy, and there would be differences in the incidences among the different osteotomy procedures. METHODS: Consecutive patients who underwent knee osteotomies for varus osteoarthritis and met the inclusion criteria were included in the study. Ultrasonographic evaluation was performed to detect DVT on bilateral whole leg at 1 month before and 7 days after surgery. Statistical comparison of the demographic and clinical parameters between the patients with and without DVT as well as multivariate analysis using logistic regression was conducted to identify risk factors related to the incidence of postoperative DVT. RESULTS: The study subjects comprised 159 knees in 135 patients with medial opening wedge high tibial osteotomy (MOW-HTO), 93 knees in 78 patients with lateral closed wedge high tibial osteotomy (LCW-HTO), and 74 knees in 54 patients with double level osteotomy (DLO). In the postoperative evaluation, DVT was detected in 19 of 159 knees (11.9%) in MOW-HTO, 21 of 93 knees (22.6%) in LCW-HTO, and 5 of 74 knees (6.8%) in DLO. The incidence of DVT was significantly higher after LCW-HTO than after MOW-HTO and DLO (p < 0.01). DVT at a level above the knee was noted in one case after MOW-HTO, while DVT in the remaining cases developed at a level below the knee. No cases of symptomatic pulmonary embolism were encountered during the study period. Among the potential risk factors assessed for correlation with the incidence of DVT, LCW-HTO was identified as a significant risk factor (odds ratio: 2.54; 95% CI 1.334-4.836; p < 0.01). CONCLUSIONS: This study demonstrated that DVT occurred at a substantial rate (overall incidence of 13.8%) after osteotomy around the knee even with the use of prophylactic anticoagulant. Among the different osteotomy types, the DVT rate was significantly higher after LCW-HTO than after MOW-HTO and DLO. LEVEL OF EVIDENCE: Prospectively designed observational cohort study, Level III.

Hinge fracture in lateral closed-wedge distal femoral osteotomy in knees undergoing double-level osteotomy: assessment of postoperative change in rotational alignment using CT evaluation.

PURPOSE: The purpose of this study was to examine the radiological features of hinge fracture occurring at the distal medial femoral cortex in knees undergoing biplanar lateral closed-wedge distal femoral osteotomy (LCW-DFO) in double-level osteotomy (DLO) based on pre- and postoperative CT image analyses. It was hypothesised that medial hinge fractures in LCW-DFO would occur with a similar incidence to that in high tibial osteotomy, and its occurrence would affect the clinical/radiological outcomes and induce unintended change in alignment depending on the fracture type (direction of the fracture). METHODS: A consecutive series of 36 knees (31 patients) with primary varus osteoarthritis undergoing DLO comprised the study population. The mean age at surgery was 62.0 ± 5.9 years. Presence of hinge fracture was assessed on radiographs and CT images at 1 week. The fracture type was classified depending on the direction of the fracture line: crack propagation in line with the osteotomy (type 1) and fractures extending proximally (type 2) or distally (type 3) from the tip of the wedge. Computer-assisted assessments of bony limb alignment and bony geometry were conducted on a full-length weight-bearing radiograph and CT images using image analysis software. In addition, subjective clinical results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS). Radiological and clinical follow-up results at 1 and 2 years were compared to the preoperative data, while comparative analysis was made between the subjects with and without a hinge fracture. RESULTS: Postoperative image examinations revealed type 1 and 2 medial femoral hinge fractures in 4 and 7 knees, while no type 3 fracture was identified in the study population. Consequently, the overall incidence of the hinge fracture was 30.6% (11 of the 36 knees). Four of those 11 fractures (36.4%) could not be detected on plain radiographs. CT image analysis for three-dimensional bony geometry showed greater increase in internal rotation of the distal bony segment (increased femoral antetorsion by 9.5° on average) after surgery compared to the knees without a hinge fracture (P = 0.01). Clinical evaluation using the KOOS at 2 years showed no significant difference between the groups with and without hinge fractures. CONCLUSION: In LCW-DFO, medial femoral hinge fractures occurred in 30.6% of the cases. Knees with type 1 hinge fracture exhibited significantly greater increase in femoral antetorsion as compared to those without hinge fracture. In this case series, postoperative weight-bearing protocol was delayed for knees with hinge fracture. Consequently, surgical results were not affected by the occurrence of hinge fracture for up to 2 years. LEVEL OF EVIDENCE: IV (case series).

Return to sports rate after opening wedge high tibial osteotomy in athletes.

PURPOSE: We hypothesized that patient treated with OWHTO who participate in high-impact sports would attain satisfactory outcome. The purpose of this study was to examine the clinical and radiological outcomes in a consecutive series of opening-wedge high tibial osteotomy (OWHTO) in highly active patients. METHODS: Seventy-seven consecutive patients who underwent OWHTO with varus osteoarthritic knees were included in the study. The mean age of the study population was 56.1 years. All patients were followed for a minimum of 2 years. Clinical and radiological evaluations were performed at 12 and 24 months after surgery. The clinical results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) Subjective Score. In regards to radiological assessment, the following parameters were measured in full-length weightbearing radiographs both pre- and postoperatively; mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), and weight bearing line (WBL) ratio. RESULTS: Fifty-eight patients (75.3%) returned to the same high-impact sports activities as before surgery, with a mean time to return of 8.7 ± 2.7 months (6-14 months). In the clinical assessments, the IKDC subjective score and KOOS both improved from the mean preoperative scores of 38.4 and 217.4 points to the mean postoperative scores of 74.5 and 421.6 points, respectively. The mean pre-symptomatic Tegner activity scale was 5.3 ± 0.6 and significantly decreased to 4.8 ± 1.2 at 2 years postoperative (p < 0.05). In the radiological evaluation, the postoperative mTFA, mMPTA, and WBL ratio values averaged 1.3° ± 2.2° valgus, 90.7° ± 2.9°, and 51.6% ± 8.4°, respectively, at 24 months after surgery. CONCLUSIONS: Clinical outcomes based on postoperative patient-reported outcome measures and rate of return to high-impact sports activities were favorable after OWHTO in patients with knee OA who desired to continue sporting activities with the Tegner activity score of ≥ 5 points. LEVEL OF EVIDENCE: Retrospective case series, IV.

Successful treatment of degenerative medial meniscal tears in well-aligned knees with fibrin clot implantation.

PURPOSE: The purpose of this study was to examine the results of meniscal repair performed for symptomatic degenerative medial meniscal tears. METHODS: Twenty-four knees in 24 patients with symptomatic degenerative medial meniscal tears (mostly complex horizontal tears) who underwent isolated arthroscopic repair combined with autologous fibrin clot implantation were included in this study. The patients were followed up for a minimum of 2 years. The overall clinical outcome was evaluated using the Lysholm score, while the activity level was graded on the Tegner Activity Scale. The assessment of healing status at the repair site was based on clinical signs/symptoms and follow-up MRI examination results. In addition, the effects of the patient's clinical and radiological factors on healing of the repaired menisci were analyzed. RESULTS: The mean age of the study subjects was 47.0 ± 8.1 years with a mean follow-up period of 39.3 ± 11.6 months. The Lysholm score significantly improved after surgery (P < 0.01). During the follow-up period, meniscal repairs were deemed to have failed in 6 of the 24 knees (25%). In the analysis of factors influencing meniscal healing, varus deformity (% of mechanical axis < 30%) was identified in all knees in the repair failure group, and the presence of varus deformity was shown to be a significant risk factor correlated with repair failure, while other factors did not significantly influence the healing status. CONCLUSIONS: The short-term follow-up results showed that arthroscopic repair of degenerative medial meniscal tears combined with fibrin clot implantation attained clinical healing in 18 of 24 knees (75%) of patients, while 6 of the 24 knees (25%) of patients experienced clinical failure. The presence of varus deformity negatively affects the healing rate. In well-aligned knees, degenerative medial meniscal tears are successfully treated by isolated repair with fibrin clot implantation. LEVEL OF EVIDENCE: IV.

Physiologic knee joint alignment and orientation can be restored by the minimally invasive double level osteotomy for osteoarthritic knees with severe varus deformity.

PURPOSE: The purpose of this study was to examine early radiological and clinical outcomes following minimally invasive double level osteotomy (DLO) procedure performed for osteoarthritic knees with severe varus deformity. METHODS: Twenty consecutive patients who underwent DLO for varus osteoarthritic knees were included in the study. All patients could be tracked for a minimum of 1 year. Periodical radiological and clinical evaluations were performed at 6 and 12 months after surgery. In the radiological assessment, the following parameters were measured on full-length weight-bearing radiographs both pre- and postoperatively: mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), and joint-line convergence angle (JLCA). In addition, subjective clinical results were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) Subjective Score. RESULTS: The mean age of the study population was 62.5 ± 6.8 years (range 45-76 years). In the radiological evaluation, the preoperative mTFA, mLDFA, mMPTA, and JLCA values averaged 13.5° ± 3.1° varus, 91.1° ± 1.4°, 82.3° ± 2.0°, and 5.8° ± 2.3°, respectively. At 6 and 12 months, all of the radiological parameters significantly improved and corrected to the values within normal range. In the clinical assessments at the follow-up evaluations, both the KOOS and IKDC subjective scores significantly improved from the preoperative values. No significant changes were noted between the 6 and 12-month results in the radiological and clinical assessments. CONCLUSIONS: The minimally invasive DLO technique is a valuable surgical technique accomplishing restoration of physiologic knee joint alignment and orientation with significant improvement in patient-registered clinical outcomes in early postoperative evaluation. Although the follow-up period is still short, the excellent clinical and radiological outcomes shown in the present study support the efficacy of this procedure. LEVEL OF EVIDENCE: Retrospective case series, Level IV.

Large correction in opening wedge high tibial osteotomy with resultant joint-line obliquity induces excessive shear stress on the articular cartilage.

PURPOSE: The purpose of this study was to analyse the resultant stress induced by joint-line obliquity after HTO for varus knee deformity using a three-dimensional (3D) finite element model analysis. METHODS: The geometrical bone data used in this study were derived from commercially available human bone digital anatomy media. The 3D knee models were developed using 3D computer-aided design software. The articular surface was overlaid with a 2-mm-thick cartilage layer for both femoral and tibial condyles. Ligament structures were simulated based on properties reported in previous anatomical studies. Regarding the loading condition, isolated axial loads of 1200 N with lateral joint-line inclinations of 2.5°, 5°, 7.5°, and 10° in reference to the horizontal axis were applied to the femur to simulate the mechanical environment in a knee with joint-line obliquity. RESULTS: A steep rise of shear stress in the medial compartment was noted in the model with obliquity of 5° or more. This laterally directed shear stress exhibited an incremental increase in accordance with the obliquity angle. The maximum shear stress value in the medial cartilage increased from 1.6 MPa for the normal knee to 3.3, 5.2, and 7.2 MPa in the joint-line obliquity models with 5°, 7.5°, and 10° of obliquity, respectively. CONCLUSIONS: The effects of HTO for varus knee deformity on the amount/distribution of stresses in the articular cartilage were analysed using a 3D finite element model. It was shown that joint-line obliquity of more than 5° induced excessive shear stress in the tibial articular cartilage. A large amount of correction in OWHTO with a resultant joint-line obliquity of 5° or more may induce detrimental stress to the articular cartilage. Double-level osteotomy should be considered as a surgical option in this situation.

Comparison of transportal and outside-in techniques for posterolateral femoral tunnel drilling in double-bundle ACL reconstruction -three-dimensional CT analysis of bone tunnel geometry.

PURPOSE: To comparatively analyze the geometry of the posterolateral femoral (PL) tunnel in double-bundle ACL reconstruction between far anteromedial transportal (TP) and outside-in (OI) drilling techniques based on three-dimensional computed tomography (3DCT) image analysis. METHODS: Forty patients who underwent anatomic double-bundle hamstring ACL reconstruction using the TP (n: 20) or OI (n: 20) method with postoperative CT data available were included in the study. The analyzed parameters were as follows: location of the intraarticular tunnel aperture, tunnel length, bending angle (angulation of the graft at the intraarticular tunnel aperture), and long axis of the tunnel aperture/drill diameter ratio as a parameter of ellipsoidal geometry. RESULTS: Anatomical tunnel placement was achieved in both groups. Coalition of the AM and PL tunnel apertures was found in 3 knees in the TP group and 1 knee in the OI group, though no significant difference in the rate of this problem was demonstrated between the groups (P: 0.30). The tunnel length was not significantly different between the groups, while the graft bending angle at the tunnel aperture was significantly larger in the OI group than the TP group (99.4° vs. 63.6°). The long axis/drill diameter ratio averaged 1.23 in the TP group and 1.13 in the OI group with significant intergroup difference. CONCLUSION: When drilling the PL femoral tunnel in double-bundle ACL reconstruction, anatomic placement of the intraarticular tunnel aperture was feasible in both the TP and OI techniques. The tunnel aperture was rounder and the graft bending angle in knee extended position at the intraarticular aperture was more acute in the OI technique than the TP technique. LEVEL OF EVIDENCE: Level IV (retrospective comparison of the two patient groups treated at different hospitals).

Persistent Hemarthrosis of the Knee after Arthroscopic Meniscal Repair.

Introduction: In this case report, we report a patient with complicated with persistent hemarthrosis following arthroscopic meniscal repair. Case Presentation. A 41-year-old male patient presented with persistent swelling of the knee 6 months after arthroscopic meniscal repair and partial meniscectomy performed for lateral discoid meniscal tear. The initial surgery was performed at another hospital. Four months after the surgery, swelling of the knee was noted when he resumed running. At his initial visit to our hospital, intra-articular blood accumulation was revealed via joint aspiration. A second arthroscopic examination performed 7 months after the initial procedure showed healing of the meniscal repair site and synovial proliferation. The suture materials identified during the arthroscopy were removed. Histological examination of the resected synovial tissue showed inflammatory cell infiltration and neovascularization. In addition, a multinucleated giant cell was identified in the superficial layer. After the second arthroscopic surgery, the hemarthrosis did not recur, and the patient was able to resume running without symptom one and a half years post-surgery. Conclusion: Bleeding from the proliferated synovia at or near the periphery of the lateral meniscus was thought to be the cause of the hemarthrosis as a rare complication following arthroscopic meniscal repair.

Postoperative Tunnel Widening, Elliptical Aperture Shape, and No Preservation of the Remnant Are Related to the Tendon Graft-Bone Tunnel Gap Formation at the Intra-Articular Aperture After Double-Bundle Anterior Cruciate Ligament Reconstruction.

Purpose: To examine the bone-tendon healing at the posterolateral (PL) femoral tunnel aperture by second-look arthroscopy after double-bundle anterior cruciate ligament reconstruction (ACLR), and assess the risk factors for impaired healing at the tendon-bone interface. Methods: A consecutive series of knees undergoing primary double-bundle ACLR using hamstring tendon autografts were enrolled in the study. The exclusion criteria were as follows: previous knee surgeries, concomitant ligamentous and osseous procedures, and a lack of second-look arthroscopy or postoperative computed tomography data for the analysis. Cases in which a gap was identified between the graft and tunnel aperture during the second-look arthroscopic examination were classified as the gap formation (GF) group. A multivariate logistic regression analysis was performed to assess the relationship between the GF and variables that may determine prognosis. Results: A total of 54 knees that met the inclusion/exclusion criteria were included in the study. Second-look arthroscopy revealed the GF at the PL aperture in 22 of the 54 knees (40%). The time period from surgery to arthroscopy averaged 16 months. In the multivariate logistic regression analysis, the percentage tunnel widening at 1 year on computed tomography (odds ratio, 10.4; 95% confidence interval [CI] 1.56-69.2), ellipticity of the tunnel aperture (odds ratio, 3.57; 95% CI, 0.79-16.11), and no ACL remnant preservation (odds ratio, 5.99; 95% CI, 1.23-29.06) were identified as prognostic factors significantly related to graft-bone tunnel GF. Conclusions: Second-look arthroscopy revealed GF at the PL graft-bone tunnel interface in 40% of the knees after double-bundle ACLR. Incomplete healing of the interface, as evidenced by a graft-bone gap at the tunnel aperture, was associated with tunnel widening 1-year postsurgery, an elliptical aperture shape, and no preservation of the ACL remnant. Level of Evidence: Ⅲ, retrospective case-control study.

Three dimensional CT analysis of the change in rotational alignment in double level osteotomy after double level osteotomy performed for varus osteoarthritic knees.

PURPOSE: To analyze the change in rotational alignment caused by double level osteotomy (DLO) based on comparative three-dimensional image analysis of pre- and postoperative CT images. METHODS: Pre- and postoperative CT examination of the lower extremities were performed with informed consent for 39 consecutive knees undergoing DLO for varus knee deformity. The DLO procedure consisted of closed wedge distal femoral osteotomy (CWDFO) and open wedge high tibial osteotomy (OWHTO). Among those cases, 20 knees complicated with hinge fracture at the osteotomy site were excluded from the analysis to eliminate a confounding factor affecting the results. Consequently, data obtained from 19 knees were subjected to the study analysis while osteotomies with hinge fractures complications were excluded from the study. In the three-dimensional CT image analysis of axial plane images, femoral torsion (the angle between midline along the femoral neck axis and the tangent of the posterior edges of the medial/lateral femoral condyles) and tibial torsion (the angle between the tangent of the posterior edges of the medial/lateral tibial condyles and the transmalleolar axis) were measured. The torsion angle was measured in each of the femurs and the tibias on both pre- and postoperative CT axial images, and the change induced by the osteotomy was calculated and statistically(using Wilcoxon signed-rank test) compared. RESULTS: The mean pre- and postoperative femoral torsion (anteversion) angles were 29.3° and 31.4° with a significant postoperative increase in internal rotation of the bony segment distal to the osteotomy(P = 0.002). On the tibial side, the mean pre- and postoperative torsion angles were 26.5° and 25.7°, indicating no significant postoperative change(P = 0.199)（NS）. CONCLUSIONS: This study showed that the DLO procedure (combining CWDFO and OWHTO) increased torsion (anteversion) of the femur by 2.1° on average while inducing no significant rotational change on the tibial side.

Double-level osteotomy for severe varus osteoarthritic knees can prevent change in leg length and restore physiological joint geometry.

BACKGROUND: It is unclear whether double-level osteotomy (DLO) combining closed-wedge osteotomy in the distal femur and open-wedge osteotomy in the proximal tibia deformity can prevent change in leg length and excessive coronal inclination of the tibial articular surface in surgical correction of the severe varus knee. The purpose of this study was to examine the postoperative change in leg length as well as radiological and clinical outcomes following DLO compared with the results obtained from knees undergoing isolated open-wedge high tibial osteotomy (OW-HTO). METHODS: In cases of severe varus knee deformity (hip-knee-ankle angle (HKA) > 10°) 29 patients undergoing DLO and 35 patients undergoing OW-HTO were included. If the predicted mechanical medial proximal tibial angle (mMPTA) was 95° or greater or the wedge size was 15 mm or greater in the surgical simulation, then DLO was considered as the surgical of option. In cases where these criteria were not met, OW-HTO was selected. All patients were followed up for a minimum of 2 years. RESULTS: The changes in the length of the whole leg in the DLO and OW-HTO groups averaged 2.3 ±â€¯4.8 mm and 9.3 ±â€¯7.2 mm, respectively (P < 0.001). mMPTA of more than 95° was found in no knee in the DLO group. CONCLUSIONS: This study showed that DLO could avoid leg length change and non-physiologic joint lines when performed in patients with varus HKA > 10°, and the predicted mMPTA was 95° or greater or the wedge size was 15 mm or greater in the surgical simulation.

Cartilage repair examined by second-look arthroscopy following double-level osteotomy performed for osteoarthritic knees with severe varus deformity.

BACKGROUND: The purpose of this study was to examine the status of cartilage repair by second-look arthroscopy following double-level osteotomy (DLO) performed for osteoarthritic knees with severe varus deformity. METHODS: Forty-seven consecutive knees in 33 patients who underwent DLO were included in the study. The surgical technique used was a minimally invasive DLO procedure combining lateral closed-wedge distal femoral and medial open-wedge high tibial osteotomies. In the second-look arthroscopic evaluation, the following grading system proposed by Koshino was adopted: Stage A, no repair; stage B, pink fibrous tissue with or without partial coverage with white fibrocartilage; and stage C, total coverage with cartilage. The findings corresponding to stage B or C were considered as repaired. Arthroscopic assessment was performed for each compartment. Clinical outcomes were evaluated using the validated outcome measures. RESULTS: The mean age at surgery was 62.8 ± 6.2 years (range: 45-75 years), and the mean time period from DLO to second-look arthroscopy was 17.1 ± 5.0 months (range: 12-33 months). Cartilage repair to some extent was identified in over 90% of the medial femoral and tibial condyles, and 12.8% of the patellar facet. As for clinical scores, both Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee Subjective Knee Form (IKDC) subjective scores significantly improved after surgery (P < 0.01). CONCLUSIONS: Evaluation of the present study subjects showed that DLO could induce cartilage repair in the majority of the affected femoral and tibial articular surfaces with significant clinical improvement. In the patellar facet, however, cartilage repair could be identified in only 12.8% of cases.

How the orientation of osteotomy in biplanar lateral closed-wedge distal femoral osteotomy influences the rotational alignment of the knee in all dimensional planes.

BACKGROUND: Correction of coronal plane deformity by osteotomies around the knee is theoretically three-dimensional (3D) and can be associated with changes in other planes. It has been shown that 3D rotational changes are induced by biplanar high tibial osteotomy; however, relevant information in biplanar lateral closed-wedge distal femoral osteotomy (LCW-DFO) has not been reported in literatures. This study aimed to investigate rotational changes in axial and sagittal planes in LCW-DFO using computer-aided design (CAD) simulations. METHODS: LCW-DFO is composed of three cuts: one ascending cut and two transverse cuts. In the simulations, the following geometrical parameters were adopted as factors potentially influencing 3D changes occurring in the osteotomy. The ascending cut angle measured as the angle between the edge of the ascending cut and the edge of the transverse cut in the lateral view, and the ascending cut obliquity measured as the angle corresponding to anterior/posterior inclination of the ascending cut with reference to the posterior condylar tangent line in the axial view. In the analysis, the effects of these bony cut angles on associated rotational changes in the axial and sagittal planes (internal/external rotation and flexion/extension) were calculated. Variation of wedge size ranged from 2 to 8 mm. RESULTS: The degree of the ascending cut obliquity substantially correlated with associated change in the sagittal plane (extension/flexion) while inducing only minimal change in rotation in the axial plane (internal/external rotation). When the osteotomy was made without ascending cut obliquity, the change in knee extension/flexion was minimal for the conditions analyzed while coupled internal rotation of the distal bony segment was induced. CONCLUSIONS: In biplanar LCW-DFO, the ascending cut angle substantially influenced the amount of internal rotation of the distal bony segment with little effect on flexion/extension angles. By contrast, ascending cut obliquity in the axial plane yields an effect on flexion/extension angles and little effect on internal rotation of the distal bony segment.

Bone Tunnel Placement Determination Method for 3D Images and Its Evaluation for Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament (ACL) injury causes knee instability which affects sports activity involving cutting and twisting motions. The ACL reconstruction surgery replaces the damaged ACL with artificial one which is fixed to the bone tunnels opened by the surgeon. The outcome of the ACL reconstruction is strongly related to the placement of the bone tunnels, therefore, the optimization of tunnel drilling technique is an important factor to obtain satisfactory surgical results. AIMS: The quadrant method is used for the post-operative evaluation of the ACL reconstruction surgery, which evaluates the bone tunnel opening sites on the lateral 2D X-ray radiograph. METHODS: For the purpose of applying the quadrant method to the pre-operative knee MRI, we have synthesized the pseudo lateral 2D X-ray radiograph from the patients' knee MRI. This paper proposes a computer-aided surgical planning system for the ACL reconstruction. The proposed system estimates appropriate bone tunnel opening sites on the pseudo lateral 2D X-ray radiograph synthesized from the pre-operative knee MRI. RESULTS: In the experiment, the proposed method was applied to 98 subjects including subjects with osteoarthritis. The experimental results showed that the proposed method can estimate the bone tunnel opening sites accurately. The other experiment using 36 healthy patients showed that the proposed method is robust to the knee shape deformation caused by disease. CONCLUSION: It is verified that the proposed method can be applied to subjects with osteoarthritis.

Tibial Tubercle-Midepicondyle Distance Can Be a Better Index to Predict the Outcome of Medial Patellofemoral Ligament Reconstruction Than Tibial Tubercle-Trochlear Groove Distance.

PURPOSE: To compare the clinical utility of tibial tubercle-midepicondyle (TT-ME) and tibial tubercle-trochlear groove (TT-TG) distances in predicting the risk for recurrent instability after isolated MPFL reconstruction. METHODS: A consecutive series of patients with recurrent patellar dislocation who underwent isolated MPFL reconstruction made up the study population. The patients were followed for a minimum of 2 years. In assessment of surgical outcome, the patient was deemed to exhibit "postoperative recurrent patellar instability" when ≥1 of the following 3 conditions was identified: redislocation, positive apprehension sign, and positive J-sign (manifestation of abnormal patellar tracking). As for radiological parameters for position of the tibial tubercle, TT-ME distance (transverse distance between the tibial tubercle and midpoint of the transepicondylar line) and TT-TG distance were measured on axial computed tomography images. The clinical utility as a factor to predict the outcome of MPFL reconstruction was compared between the 2 distances using receiver operating characteristic (ROC) analysis. In addition, various radiological indices potentially influencing the surgical outcome were subjected to multivariable logistic regression analysis. RESULTS: We examined 38 knees in 38 patients with a mean age at surgery of 17.6 years. Postoperative recurrent patellar instability was encountered in 8 of the 38 knees. The ROC curve analysis showed the TT-ME distance to be a significantly better indicator in predicting surgical outcome than the TT-TG distance (P = .001). The univariate analysis for radiological factors demonstrated that the TT-ME distance was significantly associated with postoperative recurrent patellar instability (odds ratio 1.42, P = .012) whereas all other factors including the TT-TG distance did not correlate with recurrent instability. The multivariable logistic regression analysis revealed that only the TT-ME distance was significantly associated with recurrent instability (P = .035). CONCLUSIONS: Analysis of our patient population undergoing isolated MPFL reconstruction showed that the TT-ME distance was a significantly better indicator than the TT-TG distance to predict the risk for recurrent instability after isolated MPFL reconstruction performed for patellar instability. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Clinical outcome of meniscus repair for isolated meniscus tear in athletes.

OBJECTIVE: To examine the clinical and functional outcomes for a series of patients who underwent meniscal repair for isolated meniscal tears focusing the study population on athletes. METHODS: This study represents a case series of 46 athletes who underwent repair of isolated meniscal lesions of the knee from 2010 to 2015. Cases of discoid meniscal lesions and combined ligament injuries were excluded. The mean age of the patients was 22.9 years ranging from 12 to 50 years. Arthroscopic inside-out repair was primarily a procedure of option. For repair of tears with degeneration and inferior vascularity, autogenous fibrin clot was implanted to the repair site for healing enhancement. The mean follow-up period of all patients was 19.8 ± 6.8 months (range; 12 months-33 months). RESULTS: In total, 37 of 46 patients (80%) could go back to their original sports activities. During the follow-up period, re-tear was encountered in 4 of 46 knees (8.7%). No significant differences in clinical/functional outcomes and re-tear rate were detected between the medial and lateral meniscal repairs. CONCLUSION: In our expanded repair indication for isolated meniscus repair for athletes, the rate of satisfactory return to sports was 91.3% in total (88.9% for the medial meniscus group; 92.9% for the lateral meniscus group). During the follow-up period ranging from 12 to 33 months (mean, 19.8 months), re-tear of the repaired site was encountered in 4 of the 46 knees (8.7%).