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Scoliosis is the deformity of the growing human spinal column such that the vertebral alignment is distorted in a corkscrew fashion. A person with severely deformed spine may find it difficult to breathe as the ribcage may press against the internal organs compromising the functions of the lungs and the heart. Due to the altered load transfer, these patients also suffer from back pain and early arthritis. The scoliotic deformity is surgically corrected by using implants which are screwed into the vertebra. In severe cases, complete correction may not be achievable. As a result, the loads experienced by the implants may not be optimal, leading to their early failure. The objective of this work is to study the effect on the deformity correction in a scoliotic spine. A three-dimensional model of the surgically corrected spine was segmented from the computed tomography scan and converted into a surface model. This model was imported in to ANSYS for meshing and subjected to compression load to simulate weight bearing. The stress concentration and displacement across the entire spine, individual vertebrae and discs was analysed. The effect on the implants was separately analysed as well.

PurposeChronic grade 3 tears of the medial collateral ligament and posterior oblique ligament may result in valgus laxity and anteromedial rotational instability after an isolated or multiligament injury. The purpose of this study was to prospectively analyze the restoration of physiologic medial laxity as assessed on stress radiography and patient reported subjective functional outcomes in patients who undergo an anatomic medial knee reconstruction. MethodsThis was a prospective study which included patients with chronic (> 6 weeks old) posteromedial corner injury with or without other ligament and meniscus lesions. Pre‐ and post‐operative valgus stress radiographs were performed in 20° knee flexion and functional outcome was recorded as per the International Knee Documentation Committee (IKDC) and Lysholm scores. All patients underwent anatomic medial reconstruction with two femoral and two tibial sockets using ipsilateral hamstring tendon autograft. Simultaneous ligament and meniscus surgery was performed as per the associated injury pattern. All patients were followed up for a minimum of 24 months post‐surgery. ResultsThirty‐four patients (23 males, 11 females) were enrolled in the study and all were available till final follow‐up of mean 49.7 ± 14.9 months. The mean age was 30.6 ± 7.9 (18–52 years). Two patients had isolated medial sided lesions and 23 had associated ligament injuries. The mean follow up was 49.7 (24–72) months. The mean IKDC score improved from 58 ± 8.3 to 78.2 ± 9.5 (p < 0.001). Post‐operatively there were 15 excellent, 11 good and 8 fair outcomes on Lysholm score. The mean pre‐operative valgus side‐to‐side opening improved from 7.5 ± 2.5 mm to 1.2 ± 0.7 mm on stress radiography (p < 0.001). ConclusionAnatomic reconstruction of the superficial medial collateral and posterior oblique ligaments restore stability in a consistent manner cases of chronic grade 3 instability. The objective functional results, subjective outcomes and measures of static medial stability are satisfactory in the short term. Level of EvidenceIV

Aims The mobile bearing Oxford unicompartmental knee arthroplasty (OUKA) is recommended to be performed with the leg in the hanging leg (HL) position, and the thigh placed in a stirrup. This comparative cadaveric study assesses implant positioning and intraoperative kinematics of OUKA implanted either in the HL position or in the supine leg (SL) position. Methods A total of 16 fresh-frozen knees in eight human cadavers, without macroscopic anatomical defects, were selected. The knees from each cadaver were randomized to have the OUKA implanted in the HL or SL position. Results Tibial base plate rotation was significantly more variable in the SL group with 75% of tibiae mal-rotated. Multivariate analysis of navigation data found no difference based on all kinematic parameters across the range of motion (ROM). However, area under the curve analysis showed that knees placed in the HL position had much smaller differences between the pre- and post-surgery conditions for kinematics mean values across the entire ROM. Conclusion The sagittal tibia cut, not dependent on standard instrumentation, determines the tibial component rotation. The HL position improves accuracy of this step compared to the SL position, probably due to better visuospatial orientation of the hip and knee to the surgeon. The HL position is better for replicating native kinematics of the knee as shown by the area under the curve analysis. In the supine knee position, care must be taken during the sagittal tibia cut, while checking flexion balance and when sizing the tibial component.

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