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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 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.

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.

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.

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