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To determine whether 3D-CT imaging technique is valid and reproducible compared to conventional CT measurement technique (CCT) for the detection of a femoropatellar instability.Patients who had undergone surgery for femoropatellar instability (patellar instability group) between 2010 and 2016 (n = 37 knees of 35 patients) were retrospectively enrolled. For the matched control group, patients who had acute anterior cruciate ligament injury (4 weeks previously; n = 30) were recruited. Preoperative CT data had been obtained in all patients. Inter-rater reliability was calculated for both measurement protocols, and inter-method reliability was calculated between the two imaging modalities. The results are reported using intraclass correlation coefficients (ICCs) and Bland-Altman 95% limits of agreement.All patients in the patellar instability group had femoral trochlear dysplasia (Dejour types A: four, B: 19, C: seven, and D: six), but no dysplasia was noted in the control group. In the patellar instability group, the CCT technique showed a poor inter-rater agreement (ICC = 0.74), and the 3D-CT technique still showed excellent inter-rater agreement (ICCs = 0.91). In the sub-analysis of the patellar instability group according to the trochlear dysplasia grade, ICCs were markedly decreased with severe trochlear dysplasia when using CCT technique; however, the 3D-CT technique could provide excellent reliability even with severe trochlear dysplasia.The 3D-CT imaging technique for the measurement of the TT-TG distance can be suggested as a better measurement technique for patellar instability patients with bone abnormality.

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.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.Among radiographic parameters, high fibular head, widening of the lateral joint space and femoral condylar cutoff sign showed statistically significant (p0.0001) differences between complete and incomplete DLM. At specific threshold points of fibular height11 mm, lateral joint space6 mm and condylar cutoff sign0.80, 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.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.IV, Case Series.

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.

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.

Purpose This prospective study aimed to evaluate radiographically, mechanical or hip–knee–ankle (HKA) axis in healthy, asymptomatic, Asian (Indian and Korean) adults between 20 and 40years of age to determine the incidence of inherent varus (mechanical limb alignment of >3° varus) and the factors influencing it. Methods Three hundred and eighty-eight lower limbs were evaluated using full length, standing hip-to-ankle radiographs in 198 healthy, asymptomatic, Asian (Indian and Korean) adults between 20 and 40years of age to assess the hip–knee–ankle (HKA) angle, medial proximal tibial angle (MPTA), femoral bowing and femoral neck–shaft angle to determine the incidence of inherent varus (mechanical limb alignment of >3° varus) and the factors influencing it. Results Overall, the mean HKA angle was 177.6°±2.6° with 34.5% of limbs in inherent varus (mean HKA angle 174.9°±1.8°). The incidence of inherent varus was significantly higher ( p =0.01) in males (40%) compared to females (28%) but similar among Indian (34%) and Korean subjects (35%). The hip–knee–ankle (HKA) angle showed significant positive correlation ( r =0.82, p Conclusions Inherent varus alignment of the lower limb is fairly common among asymptomatic, Asian adults. These results raise several pertinent questions regarding the role of inherent varus in the aetiopathogenesis of knee osteoarthritis and in lower limb realignment procedures.

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.

Although computer-assisted navigation in total knee arthroplasty (TKA) has many advantages, undetected tracker pin movement can result in poor lower limb alignment and component position. Osteoporosis may be an underlying cause of tracker pin movement. The present prospective case-control study compared 6-month radiographic outcomes in 44 osteoporotic and 56 non-osteoporotic knees undergoing navigation TKAs. Osteoporotic knees were defined as those having a T-score of -2.5 or less either in the femoral neck or lumbar spine or both. At postoperative 6 months' follow-up, the average coronal tibial component position was greater valgus in osteoporotic group than in nonosteoporotic group (non-osteoporotic=varus 0.7°±1.8°; osteoporotic=valgus 1.2°±3.4°; p=0.041). Multiple linear regression analysis showed that being in the osteoporotic group was a predictor of tibial coronal component position (β=0.321, p=0.039). In addition, preoperative lumbar spine bone mineral density was found to be a predictor of coronal and sagittal alignments of the tibial component (β=0.406, p=0.015, β=-0.463, p=0.007). The present study found that osteoporosis affected tibial component position in computer-assisted navigation TKA. Clinicians should be particularly aware of the possibility of undetectable tracker pin movement during navigation TKA in osteoporotic knees.

Despite several advantages of medial opening wedge high tibial osteotomy, this procedure has been noted to have a high rate of complications especially with the use of a spacer plate for fixation. We retrospectively evaluated the early complications of 138 medial opening wedge high tibial osteotomies done using autologous tricortical iliac bone graft and T-plate fixation(AO locking compression T-plate, Ti/3H 4.5-5.0 mm, Synthes, Switzerland, Model No. 440.131 in 30 and low-profile locking T-plate and low-profile locking T-plate in 128 patients. At a mean follow-up of 36.8 months (13 to 78), 26 knees (18.8%) developed complications. Complications varied from osteotomy site infection, loss of correction, broken screws and lateral tibial plateau fracture to joint fluid leakage, pseudoaneurysm and iliac bone fractures. Using the "safe zone" technique and penetrating the lateral cortex with Steinmann pins may help to avoid complications such as loss of correction and lateral tibial plateau fractures. The results of this study indicate that medial opening wedge high tibial osteotomy using autologous tricortical iliac bone graft and T-plate fixation may be a technically demanding procedure associated with a moderate rate of complications. However, these complications could be minimized with proper planning, adequate intra-operative precautions and few modifications to avoid technical error.

Some lesions such as cyst, loose body, and mass around the knee joint tend to localize at the posterior aspect of the proximal tibia. Although arthroscopic procedures of the knee joint's posterior compartment have been developed through posteromedial, posterolateral, and posterior trans-septal portals, the posterior aspect of the proximal tibia remains difficult to access and manipulate. We report an arthroscopic loose body removal and cyst decompression on the posterolateral aspect of the proximal tibia using a posterior trans-septal portal. This area represents a blind spot in knee arthroscopy.

The aim of this retrospective study was to evaluate the clinical and radiographic outcomes of arthroscopic partial meniscectomy for complete posterior medial meniscus root tear (PMMRT) in patients with early radiographic evidence of knee osteoarthritis at a minimum follow-up of 5 years.Forty-six cases had complete PMMRT with follow-up of at least 5 years and were treated with arthroscopic partial meniscectomy. On the basis of medical records, we reviewed the arthroscopic findings of joint degeneration (Outerbridge grading), clinical results using the modified Lysholm (ML) knee score and a patient questionnaire, and radiographic evaluation of degeneration using Kellgren-Lawrence (KL) grading.The incidence of complete PMMRT in the study population was 15%. At a mean follow-up of 78 months (range, 60 to 103 months), the mean ML score significantly improved from 72 (range, 62 to 78) preoperatively to 77 (range, 70 to 98) at final follow-up (P.01), 16 patients (35%) showed progression of degeneration from KL grade 0 to 2 preoperatively to KL grade 2 to 4, 56% of patients indicated improvement in pain, 67% of patients were satisfied with the results of the procedure, and 19% of patients underwent reoperation. There was a significant negative correlation between chondral wear during arthroscopy (ρ = -0.516, P = .002) and preoperative KL grade (ρ = -0.429, P = .004) with ML score at final follow-up.Although arthroscopic partial meniscectomy for complete PMMRT significantly improved ML scores postoperatively, only 56% of patients had improvement in pain, 67% were satisfied with the outcome of the procedure, and 35% showed radiographic progression of osteoarthritis at a mean follow-up of 77 months.Level IV, therapeutic study.

Our purpose was to evaluate the result of radial tears at the root of the posterior horn of the medial meniscus (PHMM) in terms of tibiofemoral contact mechanics and the effectiveness of pullout sutures for such tears.Eleven mature pig knees each underwent 15 different testing conditions with an intact, simulated (incised) radial tear at the root of the PHMM and placement of pullout sutures in the radial tears of the medial meniscus at 5 different angles of flexion (0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees ) under a 1,500-N axial load. A K-Scan pressure sensor (Tekscan, Boston, MA) was used to measure medial tibiofemoral contact area and peak tibiofemoral contact pressure. Data were analyzed to assess the difference in medial contact area and tibiofemoral peak contact pressure among the 3 meniscal conditions at various degrees of knee flexion.The mean contact area was significantly lower, and the peak tibiofemoral contact pressure was significantly high in knees with simulated radial tears at all angles of knee flexion compared with knees with intact menisci (P.0001). The peak tibiofemoral contact pressure after the pullout suture technique was significantly high at 0 degrees and 15 degrees of flexion (P.0001) compared with intact knee specimens. Failure of sutures occurred in 45% of the specimens at 0 degrees of flexion.Radial tears at the root of the PHMM in a porcine model significantly increased medial tibiofemoral contact pressure and decreased contact area. Although repair of tears of the PHMM with the pullout suture technique aids in significantly reducing tibiofemoral peak contact pressure between 30 degrees and 90 degrees , it remains significantly high at 0 degrees and 15 degrees of flexion.Pullout sutures for radial tears at the root of the PHMM may lead to an increase in peak medial tibiofemoral contact pressure and may be prone to mechanical failure, especially during the stance (loading) phase of gait (mean, 15 degrees of flexion).

Ganglion cysts of the posterior cruciate ligament (PCL) are uncommon lesions found incidentally on MRI and arthroscopy. Twenty patients (11 males and nine females) with the mean age of 35 years presenting with a variety of knee signs and symptoms were found to have PCL cysts on MRI. Out of these, thirteen patients (65%) had isolated symptomatic PCL cysts and seven patients had associated chondral and meniscal lesions. Eight out of the 20 patients (40%) gave a history of antecedent trauma. On arthroscopy, the majority of the cysts were situated at the midsubstance of the ligament with inter-cruciate distension and no involvement of the substance of the ligament. The content of the cysts varied with the majority having yellowish viscous fluid and three containing serous and bloody fluid. All cysts were successfully treated arthroscopically through standard anterior, posteromedial and posterolateral portals with no signs of recurrence on MRI at a mean followup of 24 months. PCL cysts may clinically mimic meniscal or chondral lesions and preoperatively, MRI is essential for the diagnosis of ganglion cysts arising from the PCL. Ganglion cysts of the PCL can be successfully treated arthroscopically using standard portals.

Our aim was to evaluate the alteration in angle of posterior slope of the tibia and the degree of patellar height following medial opening wedge high tibia osteotomy(HTO) using autologous tricortical iliac bone graft in 32 consecutive patients. Twenty three females and nine males underwent medial opening wedge high tibia osteotomy (HTO) using autologous tricortical iliac bone graft in 34 knees (33 primary medial compartment osteoarthritis and 1 idiopathic osteonecrosis of medial tibial condyle). The posterior slope of tibia was determined by the proximal tibial anatomical axis. Patellar height was measured by the Insall-Salvati and the Blackburne-Peel ratios. Preoperative and postoperative (last follow up) values of these three parameters were compared. The intra- and interobserver variability of these methods was determined before and after operation. At the end of mean follow up of 3 years this procedure produced no significant change in posterior slope. Pre and postoperative posterior slope were 8.7 degrees+/-3.6 degrees and 8.2 degrees+/-2.8 degrees respectively (P=0.412). Pre and postoperative Insall-Salvati ratios were 0.93+/-0.10 and 1.05+/-0.11 respectively (P0.001). The Insall-Salvati ratio increased in 94% of patients and patellar ligament length was significantly increased. The distance between the patellar and tibiofemoral joint line decreased in 82% of patients. The mean Blackburne-Peel ratio declined from 0.71+/-0.12 to 0.61+/-0.13 (P0.001). Twenty six percent of postoperative Blackburne-Peel values satisfied the radiographic criterion for patellar infera (Blackburne-Peel ratio0.54). There was no difference in the intra-and interobserver variability of measurements either before or after HTO. Opening wedge HTO using autologous tricortical iliac bone graft with internal fixation and early mobilisation prevented change in posterior slope of tibia, lengthened the patellar ligament and elevated the tibiofemoral joint line when the mean ratio of anterior and posterior gap at the osteotomy site was around two-thirds.

Kneeling is one of the activities sought by patients after total knee arthroplasty (TKA). This study investigated the six degrees of freedom (DOF) kinematics and three-dimensional (3D) contact during weight-bearing kneeling.A total of 16 South Korean female patients (22 knees) after posteriorly stabilized (PS) TKA (LPS-Flex) were randomly recruited and had the same surgeon. The patients were imaged using a dual fluoroscopic technique while they kneeled from initial to maximum flexion. The acquired images and 3D models were then used to recreate the in vivo pose of the components. Contact was determined by locating the surface intersections in the tibiofemoral and cam/post (between the femoral cam and tibial post) articular compartments.Patients flexed, on average, from 107.3 degrees to 128.0 degrees during the kneeling activity. Changes in kinematics included 1.0 mm of proximal, 0.9 mm of medial, and 7.6 mm of posterior translation and 1.7 degrees of varus rotation (P0.04). A difference in internal tibial rotation was not detected. Articular contact moved posteriorly by 5.9 mm and 6.4 mm in the medial and lateral compartments, respectively. Contact also moved medially by 3.2 mm and 5.8 mm in the medial and lateral compartments. A decrease in articular contact was observed in both condyles, and lateral condylar lift-off increased with flexion (P = 0.0001). More than 80% of the patients demonstrated cam/post engagement, which always occurred in the distal portion of the post.In this patient cohort, the knee joint was constrained during the weight-bearing activity such that femoral subluxation and dislocation were not observed. Furthermore, posterior cam/post engagement occurred only in the distal portion of the tibial post, which may improve the longevity of the post. The tibiofemoral and cam/post articular contact data presented in this study further suggest that kneeling may be performed by patients after clinically successful PS TKA who feel comfortable with the activity and are free of pain.

Corrigendum to “Early complications of medial opening wedge high tibial osteotomy using autologous tricortical iliac bone graft and T-plate fixation” [The Knee 18 (2011) 278–284] Dong Ju Chae, Gautam M. Shetty, Kook Hyun Wang, Antonio Santa Cruz Montalban Jr. , Jong In Kim, Kyung Wook Nha⁎ a Department of Orthopedic Surgery, Inje University, Ilsan Paik Hospital, Ilsan, Republic of Korea b Bonplus Hospital, Seoul, Republic of Korea