Arthroscopic posteromedial drive-through test in posterior cruciate ligament insufficiency: a new diagnostic test.

PURPOSE: The study investigated the prevalence of the posteromedial drive-through sign in patients undergoing knee arthroscopy and determined its relationship to posterior cruciate ligament (PCL) insufficiency. METHODS: A retrospective review was performed on 1,015 patients undergoing knee arthroscopy from 2009 to 2012 at two institutions. During knee arthroscopy, the ability to pass the arthroscope easily between the medial femoral condyle and the PCL is considered a positive posteromedial drive-through sign. We calculated the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of posteromedial drive-through sign for diagnosis of PCL ruptures. The posterior laxity measured by Telos stress radiograph was compared between the posteromedial drive-through sign (+) and (-) patients with PCL ruptures. RESULTS: Of the 1,015 patients, 73 (7 %) had a positive posteromedial drive-through sign. For the diagnosis of PCL rupture, a posteromedial drive-through sign had an overall accuracy of 97.6 %, sensitivity of 78.8 %, specificity of 99.3 %, positive predictive value of 91.7 % and negative predictive value of 98.1 %. For the ligament laxity examination using stress radiographs, the mean posterior tibia translation was 13.8 ± 2.2 mm, while the mean posterior translation was 10.6 ± 2.4 mm in those with a negative posteromedial drive-through sign (p < 0.05). There was no relationship between a positive posteromedial drive-through sign and age and combined injuries (n.s.). CONCLUSION: A positive posteromedial drive-through sign strongly indicates the presence of PCL injuries and this arthroscopic sign is highly associated with grade III posterior knee instability. LEVEL OF EVIDENCE: III.

Serial assessment of weight-bearing lower extremity alignment radiographs after open-wedge high tibial osteotomy.

PURPOSE: The purpose of this study was to perform a serial assessment of the radiologic parameters of the mechanical axis (MA) and the weight-bearing line (WBL) using a weight-bearing anteroposterior (AP) long-standing view of the lower extremity to determine whether the postoperative MA and WBL change with time. METHODS: A total of 90 consecutive lower limbs were examined retrospectively from a weight-bearing AP long-standing view of the lower extremity obtained from 120 patients who underwent open-wedge high tibial osteotomy (OWHTO). A total of 30 patients were excluded because of (1) complications (7 patients) such as bone graft collapse or broken screws, malunion, or nonunion arising after surgery and (2) no acquisition of a regular series of weight-bearing AP long-standing views of the lower extremity (23 patients). The AP long-standing view of the lower extremity was taken, and weight-bearing AP long-standing views of the lower extremity at 1 month, 6 months, 1 year, and 2 years postoperatively were used for assessment of serial change. The Picture Archiving Communication System (Marotech, Inc, St-Augustin-de-Desmaures, Quebec, Canada) was used for radiologic measurements of the WBL ratio and MA. Serial changes were compared between 1 month, 6 months, 1 year, and 2 years postoperatively. RESULTS: The WBL ratio progressively shifted medially, with significant changes at all time points until 1 year postoperatively (1 month to 6 months, P = .04; 6 months to 1 year, P = .04; 1 year to 2 years, P = .22). Even though the MA angle showed a similar decreasing trend, it showed no statistical difference (P > .05). CONCLUSIONS: This study showed that after OWHTO, the WBL shifts progressively medially until 1 year postoperatively. LEVEL OF EVIDENCE: Level IV, diagnostic study.

Tunnel volume enlargement after posterior cruciate ligament reconstruction: comparison of achilles allograft with mixed autograft/allograft--a prospective computed tomography study.

PURPOSE: The purpose of this study was to evaluate and compare femoral and tibial tunnel volume enlargement (TVE) after arthroscopic posterior cruciate ligament (PCL) reconstruction by remnant bundle preservation using Achilles allograft or mixed graft. METHODS: Seventy-eight patients undergoing primary arthroscopic single-bundle PCL reconstruction were initially included. Fifty-six of these patients underwent follow-up for a minimum of 1 year postoperatively and were divided into 2 groups: group A received Achilles allograft (n = 27), and group B received mixed graft (n = 29). The clinical evaluation included the International Knee Documentation Committee rating, Lysholm score, Tegner activity score, and Telos stress test (Telos, Weiterstadt, Germany). All of the patients were evaluated for TVE by computed tomography scanning at the 1-year follow-up; the results were compared with the data from 1 week postoperatively. A volume increment of more than 44%, which indicates 2 mm of widening of the tunnel diameter, was defined as TVE. RESULTS: The overall incidence of TVE after single-bundle PCL reconstruction was 3.6% (2 of 56 patients) for the femoral tunnel and 5.4% (3 of 56 patients) for the tibial tunnel. The overall mean tunnel difference between 1 week postoperatively and the final follow-up was 12.0% for the femoral tunnel and 10.6% for the tibial tunnel. The mean femoral TVE was 10.1% in group A and 13.8% in group B; the mean tibial TVE was 9.9% in group A and 11.2% in group B. These differences were not statistically significant. The functional outcome was improved in both groups, showing no statistical difference at the 1-year follow-up. CONCLUSIONS: The femoral and tibial TVE caused by single-bundle PCL reconstruction using the remnant bundle-preservation technique showed no significant differences between the Achilles allograft and the mixed graft over a short-term follow-up. Furthermore, the overall incidence of TVE in PCL reconstruction in this study was low. LEVEL OF EVIDENCE: Level II, prospective comparative study.

Predictive value of painful popping for a posterior root tear of the medial meniscus in middle-aged to older Asian patients.

PURPOSE: The purpose of this study was to determine the accuracy, sensitivity, specificity, and predictive values of a single event of painful popping in the presence of a posterior root tear of the medial meniscus in middle-aged to older Asian patients. METHODS: We conducted a retrospective review of medical records of 936 patients who underwent arthroscopic surgeries for an isolated medial meniscus tear between January 2000 and December 2010. There were 332 men and 604 women with a mean age of 41 years (range, 25 to 66 years). The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of a painful popping sensation for a posterior root tear of the medial meniscus were calculated. RESULTS: Arthroscopy confirmed the presence of posterior root tears of the medial menisci in 237 of 936 patients (25.3%). A single event of a painful popping sensation was present in 86 of these 936 patients (9.1%). Of these 86 patients with a painful popping sensation, 83 (96.5%) were categorized as having an isolated posterior root tear of the medial meniscus. The positive predictive value of a painful popping sensation in identifying a posterior root tear of the medial meniscus was 96.5%, the negative predictive value was 81.8%, the sensitivity was 35.0%, the specificity was 99.5%, and the diagnostic accuracy was 77.9%. CONCLUSIONS: A single event of painful popping can be a highly predictive clinical sign of a posterior root tear of the medial meniscus in the middle-aged to older Asian population. However, it has low sensitivity for the detection of a posterior root tear of the medial meniscus. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Second-look arthroscopic findings after open-wedge high tibia osteotomy focusing on the posterior root tears of the medial meniscus.

PURPOSE: This study examined, at second-look arthroscopy, the results of open-wedge high tibial osteotomy (HTO) focusing on root tear of the medial meniscus posterior horn (RTMMP). METHODS: Among 31 consecutive patients who underwent HTO without a meniscectomy or pullout repair for RTMMP, 20 patients were available for second-look arthroscopic evaluation. All patients had medial unicompartmental arthritis. The healing status of the RTMMP was classified as complete, incomplete, and no healing. The difference in the weight bearing line from presurgery to the last follow-up was evaluated. Osteoarthritis and chondral lesions were evaluated, as were clinical results. Correlations between healing status and other variables (weight bearing line, cartilage status, and clinical scores) were assessed. The healed (10 patients) and nonhealed (incomplete 6 patients + no healing 4 patients) groups were also evaluated with respect to other variables. RESULTS: There were 10 (50%) cases with complete healing, 6 (30%) with incomplete healing, and 4 (20%) with no healing. Kellgren-Lawrence grade did not improve according to the standing plain radiograph (P = .09). Progression of chondral lesions was not observed at second-look arthroscopy; some improvement was even observed (P = .002). The median Lysholm score improved from 58 preoperatively to 88.5 at the last follow-up. The median Hospital for Special Surgery (HSS) score also increased significantly from 62.4 (range, 50 to 76) to 87.2 (range, 80 to 92; P = .003). The comparison between healed and nonhealed groups revealed no statistical differences in all variables. CONCLUSIONS: This study revealed a high rate of healing of RTMMP after HTO without attempted repair. Healing of the meniscus was not associated with an improved clinical outcome. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Does press-fit technique reduce tunnel volume enlargement after anterior cruciate ligament reconstruction with autologous hamstring tendons? A prospective randomized computed tomography study.

PURPOSE: The purpose of this prospective, randomized, computed tomography-based study was to investigate whether the press-fit technique reduces tunnel volume enlargement (TVE) and improves the clinical outcome after anterior cruciate ligament reconstruction at a minimum follow-up of 1 year compared with conventional technique. METHODS: Sixty-nine patients undergoing primary ACL reconstruction using hamstring autografts were randomly allocated to either the press-fit technique group (group A) or conventional technique group (group B). All patients were evaluated for TVE and tunnel widening using computed tomography scanning, for functional outcome using International Knee Documentation Committee and Lysholm scores, for rotational stability using the pivot-shift test, and for anterior laxity using the KT-2000 arthrometer at a minimum of 1-year follow-up. RESULTS: There were no significant differences in TVE between the 2 groups. In group A, in which the press-fit technique was used, mean volume enlargement in the femoral tunnel was 65% compared with 71.5% in group B (P = .84). In group A, 57% (20 of 35) of patients developed femoral TVE compared with 67% (23 of 34) of patients in group B (P = .27). Both groups showed no significant difference for functional outcome (mean Lysholm score P = .73, International Knee Documentation Committee score P = .15), or knee laxity (anterior P = .78, rotational P = .22) at a minimum follow-up of 1 year. CONCLUSIONS: In a comparison of press-fit and conventional techniques, there were no significant differences in TVE and clinical outcome at short-term follow-up. LEVEL OF EVIDENCE: Level II, therapeutic study, prospective randomized clinical trial.

Peripheral nerve sheath tumor of the medial plantar nerve without tarsal tunnel syndrome: a case report.

UNLABELLED: Peripheral nerve sheath tumors are relatively uncommon soft tissue tumors, and the incidence of peripheral nerve sheath tumors localized to the plantar surface of the foot, without symptoms of tarsal tunnel syndrome, is even more rare. In this report, we present the rare case of a patient with a peripheral nerve sheath tumor originating from the medial plantar nerve in the plantar vault. The tumor was enucleated and fully excised under microscopic inspection using fine-tipped instrumentation, without en bloc resection of the associated nerve trunk. Surgeons should consider peripheral nerve sheath tumor as a cause of plantar foot pain, despite the rarity of this disorder. LEVEL OF CLINICAL EVIDENCE: 4.

Tunnel widening prevention with the allo-Achilles tendon graft in anterior cruciate ligament reconstruction: Surgical tips and short term followup.

BACKGROUND: Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction can be a serious complication, and there is controversy over how to prevent it. This study aimed to suggest surgical approaches to prevent TW using an allo-Achilles tendon graft, and then to evaluate TW after these surgical tips were applied. MATERIALS AND METHODS: Sixty two patients underwent ACL reconstruction with an allo-Achilles tendon graft. Four surgical approaches were used: Making a tibial tunnel by bone impaction, intraarticular reamer application, bone portion application for the femoral tunnel, and an additional bone plug application for the tibial tunnel. After more than 1-year, followup radiographs including anteroposterior and lateral views were taken in 29 patients encompassing thirty knees. The diameter of the tunnels at postoperation day 1 (POD1) and at followup was measured and compared. RESULTS: In 18 knees (60%), there were no visible femoral tunnel margins on the radiographs at POD1 or followup. In the other 12 cases, which had visible femoral tunnel margins on followup radiographs, the mean femoral tunnel diameter was 8.6 mm. In the tibial tunnel, the mean diameters did not increase on all three levels (proximal, middle, and distal), and there was no statistically significant difference between the diameters at POD1 and followup. CONCLUSION: The suggested tips for surgery involving an allo-Achilles tendon graft can effectively prevent TW after ACL reconstruction according to this case series. These surgical tips can prevent TW.

A Combined Closing Wedge Distal Femoral Osteotomy and Medial Reefing Procedure for Recurrent Patellar Dislocation with Genu Valgum.

PURPOSE: Recurrent patellar dislocation is often associated with genu valgum. The purpose of this study was to analyze the short-term results of single-incision, closing-wedge distal femoral osteotomy (CWDFO) combined with medial reefing and lateral release for recurrent patellar instability with genu valgum. MATERIALS AND METHODS: Combined CWDFO/medial reefing/lateral release was performed on 10 knees. Clinical evaluation was based on pre- and postoperative Knee Society Score (KSS) and Kujala patellofemoral score. Radiographic evaluation was performed with reference to the weight-bearing line (WBL), the femorotibial angle (FTA), and the mechanical lateral distal femoral angles in the knee-standing view. RESULTS: At a mean follow-up of 20±11.7 months (range, 12-42 months), KSS scores improved significantly, from 46.7±5.2 preoperatively to 87±4.4 postoperatively (p<0.001), as did the Kujala score, from 44±8 preoperatively to 86.6±6.8 postoperatively (p<0.001). The WBL decreased significantly, from 76±7% preoperatively to 41±11% postoperatively (p<0.001). The FTA was improved significantly, from 12.7±1.7° preoperatively to 4±4° postoperatively (p<0.001), as was the mLDFA, from 83±4° preoperatively to 91±1.3° postoperatively (p<0.001). CONCLUSION: Use of single-incision CWDFO combined with medial reefing and lateral release prevents patellar dislocation, corrects deformity, and improves clinical outcomes.

Anatomical Single-bundle Anterior Cruciate Ligament Reconstruction Using a Freehand Transtibial Technique.

PURPOSE: In anatomical single-bundle (SB) anterior cruciate ligament (ACL) reconstruction, the traditional transtibial approach can limit anatomical placement of the femoral tunnel. SURGICAL TECHNIQUE: We present a novel three-point freehand technique that allows for anatomic SB ACL reconstruction with the transtibial technique. MATERIALS AND METHODS: Between January 2012 and December 2012, 55 ACL reconstructions were performed using the three-point freehand technique. All the patients were followed for a minimum of 12 months post-operatively. Clinical evaluation was done using the Lysholm score and International Knee Documentation Committee (IKDC) grade. All patients were analyzed by 3-dimensional computed tomography (3D CT) at 1 week after surgery. RESULTS: The mean Lysholm score improved from 68.2±12.7 points preoperatively to 89.2±8.2 points at final follow-up. At final follow-up, the IKDC grade was normal in 42 patients and nearly normal in 13 patients. None of the patients had a positive pivot shift test, anterior drawer test and Lachman test at final follow-up. The anatomical position of the femoral tunnel was confirmed on 3D CT scans. CONCLUSIONS: The three-point freehand technique for SB transtibial ACL reconstruction is a simple, anatomic technique showing good clinical results.

Radiographic evaluation of complete and incomplete discoid lateral meniscus.

OBJECTIVES: The aim of this retrospective study was (1) to evaluate the radiographic features to differentiate arthroscopically confirmed complete and incomplete discoid lateral meniscus (DLM) (2) to determine the cutoff values for any parameter that was found to differentiate complete from incomplete DLM. MATERIALS AND METHODS: We retrospectively analyzed plain knee radiographs of 130 arthroscopically proven DLM. Seventy-nine patients had complete DLM and 51 patients incomplete DLM. Knee radiographs from 52 patients with arthroscopically proven normal lateral meniscus acted as control group. Radiographic parameters measured included fibular height, lateral joint space, condylar cutoff sign, height of lateral tibial spine, obliquity of lateral tibial spine, squaring of the lateral femoral condyle, and cupping of the lateral tibial plateau. RESULTS: Among radiographic parameters, high fibular head, widening of the lateral joint space and femoral condylar cutoff sign showed statistically significant (p<0.0001) differences between complete and incomplete DLM. At specific threshold points of fibular height<11 mm, lateral joint space>6 mm and condylar cutoff sign<0.80, the diagnosis of complete DLM revealed 87.3% sensitivity, 81.6% specificity and 78.4% positive predictive value (PPV) for the fibular height, 81.0% sensitivity, 86.6% specificity and 83.1% PPV for the lateral joint space, and 86.1% sensitivity, 83.5% specificity and 80% PPV for the condylar cutoff sign. CONCLUSIONS: Radiographic features of fibular height, lateral joint space and condylar cut off sign can be used for screening of a complete type of DLM. However, radiographs are not a reliable screening tool for an incomplete DLM. LEVEL OF EVIDENCE: IV, Case Series.

Spontaneous healing of a displaced bucket-handle tear of the lateral meniscus in a child.

Bucket-handle tears less frequently occur in the lateral meniscus than in the medial meniscus. An 11-year-old male patient complained of painful swelling and locking due to a displaced bucket-handle tear of the lateral meniscus. We recommended an arthroscopic surgery; however, the patient left the hospital without surgical treatment. Six weeks afterwards, he returned without any complain of pain and he regained full range of motion. The final follow-up magnetic resonance imaging showed reduction of the torn meniscal fragment without any signal changes suggestive of a meniscal tear. We report a rare case of an isolated displaced bucket-handle tear of the lateral meniscus in an 11-year-old patient that healed spontaneously without surgical intervention.

Biomechanical properties of a new anatomical locking metal block plate for opening wedge high tibial osteotomy: uniplane osteotomy.

PURPOSE: The purpose of this study was to evaluate the biomechanical properties of a new anatomical locking metal block plate by comparing the initial biomechanical stability of three different fixation constructs for open wedge high tibial osteotomy (HTO). MATERIALS AND METHODS: Sawbones composite tibiae were used to make a 10-mm opening osteotomy model with uniplane technique. The osteotomy was secured with three different types of plates: Group I, new osteotomy plate without a metal block (n=5); Group II, new osteotomy plate with a 10-mm metal block (n=5); and Group III, two short metal block plates (n=5). Single load to failure test and staircase load-controlled cyclical failure test were performed. In the single load to failure test, the yield load, maximum failure load, and the displacement of the osteotomy gap were measured. In the staircase cyclical load to failure test, the total number of cycles to failure was recorded. Failure modes were observed during both single and cyclic load tests. RESULTS: Group II showed the highest yield and ultimate loads (1829±319 N, 3493±1250 N) compared to Group I (1512±157 N, 2422±769 N) and Group III (1369±378 N, 2157±210 N, p<0.05). The displacement of the opening gap in Group II (0.34±0.35 mm) was significantly lesser than the other groups (p<0.05). In the staircase cyclical load to failure test, the total number of cycles to failure was 12,860 at 950 N in Group III, 20,280 at 1,140 N in Group I, and 42,816 at 1,330 N in Group II (p<0.05). All the specimens showed complete fracture of the intact lateral sawbones area and slight displacement of the distal fragment of the specimens in the single load to test. None of the specimens showed deformed or broken screws and plates during the single load to test. During the fatigue test with staircase cyclic loading, no fracture of the lateral sawbones area was observed. CONCLUSIONS: This study demonstrated that the new anatomical locking metal block plate could provide sufficient primary stability for open wedge HTO. The addition of a metal block to this new plate can increase the stability of the osteotomy compared to the one without a metal block.

Localized pigmented villonodular synovitis of the proximal tibiofibular joint.

Pigmented villonodular synovitis (PVNS) is a rare disease. It is a benign neoplastic process typically affecting young to middle-aged adults and most commonly involving the knee, hip, and shoulder joints. The symptoms include diffuse pain and swelling with discomfort. We report a rare case of localized PVNS originating at the proximal tibiofibular joint in a 39-year-old female patient with radiologic changes for short duration of time. The clinical history, plain radiographs, magnetic resonance imaging, and pathologic findings of the reported patient were reviewed. Complete surgical excision was performed and there was no evidence of recurrence after one-year follow-up.

The weight-bearing scanogram technique provides better coronal limb alignment than the navigation technique in open high tibial osteotomy.

BACKGROUND: Successful outcomes following high tibial osteotomy (HTO) require precise realignment of the mechanical axis of the lower extremity. The present study investigated whether the weight-bearing limb scanogram (WBS) technique provided a more accurate mechanical axis realignment than the navigation technique in open high tibial osteotomy (OHTO). METHODS: This prospective study involved 80 knees (78 patients) undergoing OHTO. The WBS technique was used in 40 knees and the navigation technique in 40 knees. Each technique was performed by a different surgeon in a different hospital. Postoperative coronal limb alignment was assessed using the weight-bearing line (WBL) ratio on full-length standing hip-to-ankle radiographs. RESULTS: We found that the mean postoperative WBL ratio was greater in the WBS compared to the navigation group (p=0.001), and hence the ratio for the WBS group was closer to the ratio target of 62%. There was a greater proportion of WBL ratio outliers in the navigation group than the WBS group (25% vs. 10%, p=0.034). CONCLUSION: We conclude that the WBS technique was more accurate than the navigation technique for restoration of coronal leg alignment in OHTO. LEVEL OF EVIDENCE: Level II.

Arthroscopic Excision of Solitary Intra-articular Osteochondroma of the Knee.

Osteochondroma is the most common benign tumor of the growing bone commonly involving the knee joint region. It often involves the metaphysis of the long bone, occurring extra-articularly. In spite of this, solitary intra-articular osteochondroma has rarely been reported in the literature. A 41-year-old man presented with diffuse pain and discomfort of the left knee for over 2 months. Clinical examination revealed a bony prominence involving the superolateral aspect of the left distal femur. Diagnostic evaluation involved radiography, magnetic resonance imaging, and a diagnostic arthroscopy, which showed features of an intra-articular osteochondroma in the left distal femur. Arthroscopic excision of the solitary intra-articular osteochondroma resulted in a complete relief of symptoms and return to full competitive activities. No recurrence of symptoms occurred during the one year of follow-up. Solitary intra-articular osteochondroma of the knee is an unusual case, which can be successfully managed with arthroscopy.

Patellar dislocation with genu valgum treated by DFO.

Congenital habitual patellar dislocation is a rare condition of the knee where the patella dislocates during flexion and relocates during extension. The congenital form is permanent, irreducible, and presents at birth. It is characterized by a short quadriceps and a major patellofemoral dysplasia and short height. This article presents a rare case of a 27-year-old woman with recurring bilateral habitual dislocation of the patella after a failed previous proximal and distal realignment procedure. Clinical examinations of both knees revealed genu valgus knees and lateral joint pain that recurred after several previous operations. Radiographs of both knees showed patellar dislocation and genu valgum associated with patellofemoral dysplasia and osteoarthritis of the lateral compartment. Long-leg standing radiographs showed an anatomic tibiofemoral angle of right 13° and left 6° valgus and a mechanical tibiofemoral angle of right 8° and left 2° valgus and weight-bearing line of 65% on the right and 48% on the left. The authors performed a distal femoral closing wedging osteotomy to correct the valgus deformity, and then percutaneous lateral release and medial reefing were performed to stabilize the patellas of both knees simultaneously.

Arthroscopic hybrid fixation of a tibial eminence fracture in children.

The treatment of an anterior cruciate ligament (ACL) avulsion fracture is controversial, especially in skeletally immature patients, because of concerns about physeal damage. To reduce the risk of physeal injury, an arthroscopic technique was performed. A bioabsorbable suture anchor was inserted through anteromedial portals and fixed to a bioabsorbable suture anchor at the center of the fracture bed; it was then passed through the threads at the ACL avulsion fragment and tied with the ACL substance. After this, the avulsion fragment was repaired by an all-inside technique between the distal portion of the ACL and the transverse ligament and periosteum by a suture hook. The arthroscopic hybrid technique using a suture anchor with an all-inside repair is more rigid and safe. In addition, this physeal-sparing fixation is possible in immature patients.

Application of computational lower extremity model to investigate different muscle activities and joint force patterns in knee osteoarthritis patients during walking.

Many experimental and computational studies have reported that osteoarthritis in the knee joint affects knee biomechanics, including joint kinematics, joint contact forces, and muscle activities, due to functional restriction and disability. In this study, differences in muscle activities and joint force patterns between knee osteoarthritis (OA) patients and normal subjects during walking were investigated using the inverse dynamic analysis with a lower extremity musculoskeletal model. Extensor/flexor muscle activations and torque ratios and the joint contact forces were compared between the OA and normal groups. The OA patients had higher extensor muscle forces and lateral component of the knee joint force than normal subjects as well as force and torque ratios of extensor and flexor muscles, while the other parameters had little differences. The results explained that OA patients increased the level of antagonistic cocontraction and the adduction moment on the knee joint. The presented findings and technologies provide insight into biomechanical changes in OA patients and can also be used to evaluate the postoperative functional outcomes of the OA treatments.