Yoshio Matsui

Rotational deformity in varus osteoarthritis of the knee: Analysis with computed tomography

Rotational deformities in varus osteoarthritis of the knee were evaluated with computed tomography. Preoperative computed tomography scans of 150 knees (114 patients) having total knee arthroplasty and 31 control knees (20 patients) were included. The femorotibial rotation was quantified using the clinical epicondylar axis of the femur and the tibial tuberosity (patella tendon) as the references. The knees with osteoarthritis were divided into three groups according to the femorotibial angle (Group 1, 0°–9° varus, n = 87; Group 2, 10°–19° varus, n = 51; Group 3, 20° or greater varus, n = 12) and statistically analyzed. Rotational deformities (external rotation of the tibia) existed in knees with osteoarthritis and were larger in knees with increased varus deformities (mean ± standard deviation, −2.24° ± 4.19° in Group 1; 0.33° ± 4.14° in Group 2; and 5.33° ± 5.71° in Group 3). When the femorotibial rotation of each knee was stratified by the corresponding femorotibial angle, we found a correlation. The information should help minimize the rotational mismatch between the femoral and the tibial components in total knee arthroplasty and elucidate the pathogenesis of varus osteoarthritis of the knee. Level of Evidence: Diagnostic study, Level III-1 (study of nonconsecutive patients—no consistently applied reference gold standard). See the Guidelines for Authors for a complete description of levels of evidence.

Meniscal Bearing Dislocation of Unicompartmental Knee Arthroplasty with Faint Symptom.

We experienced two cases of atypical lateral dislocations of meniscal bearing in UKA (unicompartmental knee arthroplasty) without manifest symptoms. The dislocated bearing, which jumped onto the wall of tibial components, was found on radiographs in periodic medical examination although they could walk. Two thicker size bearing exchanges were promptly performed before metallosis and loosening of components. Continual examination is important to mobile bearing type of UKA because slight or less symptoms may disclose such unique dislocation. One case showed malrotation of the femoral component on 3D image. Anteroposterior view hardly disclosed the malrotation of the femoral component. Epicondylar view is an indispensable view of importance, and it can demonstrate the rotation of the femoral component. The the femoral distal end is wedge shaped and is wider posteriorly. If the femoral component is set according to the shape of medial condyle, the femoral component shifts to medial site compared with tibial component in flexion. It can account for such rare dislocation as follows. If excessive force applies on most medial side of the bearing during flexion, the lateral part of the bearing pops and the force squeezes it laterally simultaneously. Finally, the bearing jumps onto the lateral wall of the tibial component.

Flexion Gap in the Isolated Posterior Cruciate Ligament–Injured Knee Affects Symptom Relief After Conservative Treatment: A Case-Control Study:

Background: The posterior cruciate ligament (PCL) is a primary stabilizer of the knee in the posterior direction. However, PCL deficiency presents a clinical paradox because the outcome of PCL deficiency ranges from total disability to uninterrupted participation in competitive athletics. Purpose: To investigate whether posterior laxity (PL) and the flexion gap (FG) influence the results of the conservative treatment of isolated PCL injuries. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 27 patients (23 men, 4 women; mean age, 33 ± 14 years) with isolated PCL injuries between 2007 and 2013 were included in this study. All patients had been treated conservatively for more than 6 months. Nineteen patients achieved excellent relief of their symptoms (conservative treatment [C] group). Eight patients underwent PCL reconstruction owing to their symptoms (surgical treatment [S] group). Side-to-side differences of the FG and the PL were retrospectively measured on axial radiographs and on lateral radiographs with gravity sag views, respectively, and the degree of PCL injury was graded as I (PL, <5 mm) in 7 patients and II (PL, 5 to <10 mm) in 20 patients. Results: The mean PL and FG were 6.9 ± 2.5 mm and 2.0 ± 1.8 mm, respectively. A mild positive correlation between the PL and the FG was observed (r = 0.47, P = .02). The mean PL and FG were 6.5 ± 2.9 mm and 1.2 ± 1.0 mm in the C group and 7.7 ± 1.3 mm and 3.8 ± 2.0 mm in the S group, respectively. The FG in the C group was significantly smaller than that in the S group (P < .05), although there was no significant difference between the groups for PL. All patients with grade I injury belonged to the C group, for which the FG was less than 2 mm in all cases. Eight of the patients with grade II injury were in the S group, and their FG was more than 2 mm, except in 1 patient. The FG performed better with an area under the receiver operating characteristic curve of 0.924 (95% CI, 0.000-1.000) compared with 0.599 (95% CI, 0.388-0.809) for the PL. Discrimination between the C and S groups with a cutoff set at 2.30 mm for the FG and 7.45 mm for the PL showed a sensitivity of 75.0% and 75.0% and a specificity of 89.5% and 52.6%, respectively. Conclusion: Considering that the FG affects the outcome of conservative treatment, it could be a factor in the indication for the surgical treatment of isolated PCL injuries.

Intraoperative Manipulation for Flexion Contracture During Total Knee Arthroplasty.

Joint gap balancing during total knee arthroplasty (TKA) is important for ensuring postoperative joint stability and range of motion. Although the joint gap should be balanced to ensure joint stability, it is not easy to achieve perfect balancing during TKA. In particular, relative extension gap shortening can induce flexion contracture. Intraoperative manipulation is often empirically performed. This study evaluated the tension required for this manipulation and investigated the influence of intraoperative manipulation on the joint gap in cadaveric knees. Total knee arthroplasty was performed in 6 cadaveric knees from whole body cadavers. Flexion contracture was induced using an insert that was 4 mm thicker than the extension gap, and intraoperative manipulation was performed. Study measurements included the changes in the joint gap after manipulation at 6 positions, with the knee bending from extension to 120° flexion, and the manipulation tension that was required to create a 4-mm increase in the gap. The manipulation tension needed to create a 4-mm increase in the extension gap was 303±17 N. The changes in the joint gap after manipulation were 0.4 mm, 0.6 mm, 0.2 mm, -0.2 mm, -0.4 mm, and -0.6 mm at 0°, 30°, 45°, 60°, 90°, and 120° flexion, respectively. Therefore, the joint gap was not significantly changed by the manipulation. Intraoperative manipulation does not resolve flexion contracture. Therefore, if flexion contracture occurs during TKA, treatment with additional bone cutting and soft tissue release is likely more appropriate than manipulation. [Orthopedics. 2016; 39(6):e1070-e1074.].