Introduction

Accurate soft tissue balancing in knee arthroplasty is essential in order to attain good postoperative clinical results. In mobile-bearing UKA (Oxford Partial Knee unicompartmental knee arthroplasty, Biomet), since determination of the thickness of the spacer block depends on the individual surgeon, it will vary and it will be difficult to attain appropriate knee balancing. The first objective of the present study was to investigate flexion and extension medial unicompartmental knee gap kinematics in conjunction with various joint distraction forces. The second objective of the study was to investigate the accuracy of gap measurement using a spacer block and a tensor device.

Total Knee Arthroplasty (TKA) has been widely performed and successful clinical outcomes have been achieved for the patients with knee osteoarthritis which is generally known to cause ADL problem. Clinical and radiographic evaluations are commonly used when evaluating postoperative outcomes, among which kinetic analysis and gait analysis are considered essential to investigate the more detailed effect of the treatment. There is a controversy whether performing TKA on both knees simultaneously is appropriate in treating patients with bilateral knee osteoarthritis, in terms of the speed and effectiveness of gait recovery. In this study, we reviewed the significance of performing simultaneous bilateral TKA, by the results of preoperative and postoperative gait analysis.

Materials and Methods: Total of eight patients, all female and diagnosed of bilateral knee osteoarthritis, were treated with TKA and reviewed. Mean age was 70 years old (60–74). For prosthesis, we used Scorpio NRG PS, and ADVANCE, with cementation for all. No patella was replaced. Some had unilateral TKA, and some were treated bilaterally as needed. We examined distance factors (step length and step width), gait velocity, and gait barycentric factors (single-support phase and Ratio of center of gravity maximum values). We performed the analysis preoperatively, postoperatively at 1 month, 3 months, and 6 months. We used the floor pressure gauge (NITTA CORPORATION) and the three-dimensional motion analysis device (DITECT Co. Ltd) for the analysis.

Results: During the six-month follow-ups, six cases were unilateral TKA and two were treated bilaterally. Increase in step length was seen in the unilateral cases, and it decreased in the bilateral cases. Step width decreased in five cases, two cases showed no change, and increased in one case. Gait velocity had increased in all cases. Single-support phase was close to 1 for all the cases. Ratio of center of gravity maximum values, which indicates the movement of centroid during ambulation, the ratio went up for unilateral cases while it showed no change in the bilateral cases.

Discussion: Quantitative studies of gait analysis have reported that gait condition had improved after TKA. However, some reported that the gait impairment had remained. Unilateral TKA group showed gait restoration, whereas gait abnormality in either leg was seen in the bilateral group. Gait analysis is effective in determining whether surgeons should perform unilateral TKA or bilateral TKA to the patients with bilateral knee osteoarthritis. Among the gait analysis factors, we consider that Ratio of center of gravity maximum values shows effectively the improvement of the treated knee, gait, and the condition of contralateral knee.

Objective: To clarify whether serum melatonin levels in adolescent idiopathic scoliosis correlate with curve progression, and whether the exogenous melatonin treatment is effective in patients with decreased levels of endogenous melatonin in adolescent idiopathic scoliosis.

Method: A total of 63 adolescents were studied; 38 with adolescent idiopathic scoliosis and 25 age matched control subjects. We divided the patients into stable (28 patients) and progressive (10 patients) groups based on the scoliotic curve measured radiographically at three to six month intervals. The level of melatonin was considered low if it fell below the mean – 2.0 standard deviation established in normal adolescents throughout the 24 hour period or nocturnal (0:00 – 6:00 hour) integrated concentration. Oral melatonin replacement (3mg / before bedding) was administered in patients with decreased endogenous melatonin. The patients with low melatonin were treated with a brace, melatonin or both combined. During melatonin treatment, the level of melatonin was measured yearly for a period ranging from three to six years.

Results: In all subjects the melatonin levels showed diurnal variations; low during the day and high at night. Of 38 patients with adolescent idiopathic scoliosis, 22 patients had normal melatonin and 16 had low melatonin. Of 22 patients with a normal melatonin, 10 of 15 treated with brace and 6 of 7 untreated patients had stable scoliosis, and the remaining six had a progressive scoliosis. Of 16 patients with low melatonin, eight of nine treated only with melatonin, and four of seven treated with melatonin and brace had stable scoliosis. The remaining four had a progressive course. Of the 10 patients who had progressive scoliosis in normal and low levels of melatonin, nine had greater than 40 degrees of curve at the initial examination.

Conclusion: These findings suggest that transient melatonin deficiency may be associated with deterioration of scoliosis and that melatonin level may serve as a useful predictor for progression of spine curvature in patients with idiopathic scoliosis. Also, the results of this study suggest a possible role of melatonin supplement in the prevention of progressive scoliosis especially in mild cases showing less than a 40° curve.

Supported by the Fondation Yves Cotrel, Institut de France.