Longitudinal tear of the medial meniscus posterior horn in the anterior cruciate ligament-deficient knee significantly influences anterior stability.

BACKGROUND: Longitudinal tears of the medial meniscus posterior horn (MMPH) are commonly associated with a chronic anterior cruciate ligament (ACL) deficiency. Many studies have demonstrated the importance of the medial meniscus in terms of limiting the amount of anterior-posterior tibial translation in response to anterior tibial loads in ACL-deficient knees. HYPOTHESIS: An MMPH tear in an ACL-deficient knee increases the anterior-posterior tibial translation and rotatory instability. In addition, MMPH repair will restore the tibial translation to the level before the tear. STUDY DESIGN: Controlled laboratory study. METHODS: Ten human cadaveric knees were tested sequentially using a custom testing system under 5 conditions: intact, ACL deficient, ACL deficient with an MMPH peripheral longitudinal tear, ACL deficient with an MMPH repair, and ACL deficient with a total medial meniscectomy. The knee kinematics were measured at 0°, 15°, 30°, 60°, and 90° of flexion in response to a 134-N anterior and 200-N axial compressive tibial load. The rotatory kinematics were also measured at 15° and 30° of flexion in a combined rotatory load of 5 N·m of internal tibial torque and 10 N·m of valgus torque. RESULTS: Medial meniscus posterior horn longitudinal tears in ACL-deficient knees resulted in a significant increase in anterior-posterior tibial translation at all flexion angles except 90° (P < .05). An MMPH repair in an ACL-deficient knee showed a significant decrease in anterior-posterior tibial translation at all flexion angles except 60° compared with the ACL-deficient/MMPH tear state (P < .05). The total anterior-posterior translation of the ACL-deficient/MMPH repaired knee was not significantly increased compared with the ACL (only)-deficient knee but was increased compared with the ACL-intact knee (P > .05). A total medial meniscectomy in an ACL-deficient knee did not increase the anterior-posterior tibial translation significantly compared with MMPH tears in ACL-deficient knees at all flexion angles (P > .05). In a combined rotatory load, tibial rotation after MMPH tears or a total medial meniscectomy in an ACL-deficient knee were not affected significantly at all flexion angles. CONCLUSION: This study shows that an MMPH longitudinal tear in an ACL-deficient knee alters the knee kinematics, particularly the anterior-posterior tibial translation. MMPH repair significantly improved anterior-posterior tibial translation in ACL-deficient knees. CLINICAL RELEVANCE: These findings may help improve the treatment of patients with ACL and MMPH longitudinal tear by suggesting that the medial meniscal repairs should be performed for greater longevity when combined with an ACL reconstruction.

Comparison of radiographic and computed tomographic measurement of pedicle and vertebral body dimensions in Koreans: the ratio of pedicle transverse diameter to vertebral body transverse diameter.

This study was designed to investigate the characteristics of pedicle transverse diameters (PD), vertebral body transverse diameters (VBD), especially the ratios of PD/VBD (CT ratio), which has never been discussed, in Koreans using computed tomography (CT) scans and to evaluate the possibility of obtaining more accurate estimations of PD from plain radiographs using the CT ratios in each spine level. The T1-L5 vertebrae of 50 participants were analyzed prospectively with CT scans (CT-VBD and CT-PD), and the T9-L5 vertebrae of the same participants were investigated with plain radiographs (X-VBD and X-PD). The CT ratio had a higher correlation with the CT-PD (r2 = 0.630) from T1 to L5, especially in the lower thoracic and lumbar spine (T9-L5, r2 = 0.737). The correlation of VBDs between the two radiologic tools (r2 = 0.896) was higher than that of the PDs (r2 = 0.665). Based on the data, equations for the estimation of a more accurate PD from plain radiographs were developed as follows: estimated PD = estimated VBD × [1.014 × (X-VBD) + 0.152] × the mean CT ratio at each spinal level. The correlation between the estimated PD and the CT-PD (r2 = 0.852) was improved compared with that (r2 = 0.665) between the X-PD and the CT-PD. In conclusion, the CT ratio showed a very similar changing trends to CT-PD from T1 to L5 regardless of sex and body mass, and the measurement error of PD from only plain radiographs could be minimized using estimated VBD and the mean CT ratio at each spinal level.

Transradioulnar single Kirschner-wire fixation versus conventional Kirschner-wire fixation for unstable fractures of both of the distal forearm bones in children.

The purpose of this study was to introduce transradioulnar single Kirschner-wire (K-wire) fixation technique for unstable fractures of both of the distal forearm bones in children and to evaluate the differences in clinical and radiographic results of osteosynthesis between this method and conventional K-wire fixation. Forty-one patients (20 conventional K-wire fixation, 21 transradioulnar single K-wire fixation) were reviewed who underwent a closed or mini-open reduction with K-wire fixation for fractures of both of the distal forearm bones. Their mean age at operation was 10.7 years (range, 8-16 years). Surgical intervention was indicated (1) when in addition to a complete ulnar fracture, the radius showed a 50% of displacement or greater, or 20-degree angulation or greater, (2) when in addition to an incomplete ulnar fracture, the radius was completely displaced, and (3) when reangulation was 15 degrees or greater in any direction at follow-up. The minimum follow-up period was 2 years. Bony union was achieved in both groups at approximately 7 weeks after surgery, and there were no significant differences in the operative time, duration of hospitalization, and duration of external support between the 2 groups. There were no major complications such as nonunion, radioulnar synostosis, premature physeal closure, or redisplacement or reangulation. Transradioulnar single K-wire fixation technique was a relatively simple procedure with comparable outcomes compared with conventional K-wire fixation technique. In addition, physeal injuries could be avoided, and there was no need for passing across the fracture line. Thus, it is suggested that transradioulnar single K-wire fixation technique can be a good alternative method for high-risk fractures of both of the distal forearm bones in children.