Gap balanced adjusted mechanical alignment versus measured resection mechanical alignment: a randomised controlled trial.

INTRODUCTION: Alignment goals in total knee replacement (TKR) is a topical subject. This study compares the short-term functional outcomes and patient reported outcome measures (PROMs) of two philosophies for knee arthroplasty alignment: measured resection (MR) and an individualised alignment philosophy, with the tibia mechanically aligned and an instrumented gap balancer (GB) to align the femur in both flexion and extension. PATIENTS AND METHODS: 94 knees were enrolled in this randomised controlled trial. The surgical protocol used a MR technique for mechanical alignment or a GB technique for individualised alignment. Primary outcome was quadriceps strength. Secondary outcomes included validated functional tests and PROMs as well as patient satisfaction. Outcomes were assessed pre-operatively, at 6 weeks, 3, 6 and 12 months post-operatively. RESULTS: At 12-month follow-up, there was no significant difference in the change from baseline mean quadriceps peak torque between the two groups (p = 0.988). Significant improvement in the change in range of motion (ROM) in the GB group compared to the MR group at 3 months (13° vs 6° p = 0.028) but this improvement was not significant at 1 year (20° vs 17° p = 0.21). The functional test of balance showed statistically significant improvement at 6 weeks (p = 0.03) in the GB group but this difference was not maintained. PROMs favoured the GB group, with the KOOS pain scoring statistically better (p ≤ 0.05) at 6 weeks, 3, 6 and 12 months. CONCLUSIONS: Individualised alignment philosophy utilising a GB technique did not demonstrate an improvement in the primary outcome measure quadriceps peak torque. Improvement was seen in the GB group in PROM pain scores that was significant, both statistically and clinically, out to at least 1 year. Gains that were seen in functional assessment with GB, although significant at some time points, were no longer significant at 1 year and no difference was seen in quads strength. Compared to a MR technique, the individualised GB technique appears to confer some improvement in pain, ROM and some functional tests following TKR in the short-term.

A Randomised Controlled Trial of Local Infiltration Analgesia Versus Femoral Nerve Block for Postoperative Analgesia Following Total Knee Arthroplasty.

Background Total knee replacement is often associated with significant postoperative pain. Although the use of a femoral nerve block is well-established, local infiltration analgesia has gained popularity in recent years. We compared single-shot local infiltration analgesia with a single-shot femoral nerve block for patients undergoing primary total knee arthroplasty. Methods A total of 194 patients were randomised to receive either local infiltration analgesia (150 ml bupivacaine 0.067% with adrenaline) or a femoral nerve block (20 ml 0.375% levobupivacaine). Both groups received spinal anaesthesia. The primary outcome measure was the total morphine consumption. Secondary outcome measures included: post-operative pain scores, rehabilitation goals, readiness for discharge, and physical, mental, and functional outcomes, including the Oxford Knee Score (OKS). Results A total of 69 patients in the local infiltration analgesia group and 79 patients in the femoral nerve block group were analysed. Median total morphine consumption was significantly greater in the local infiltration analgesia group as compared to the femoral nerve block group (54.67 mg vs 45 mg, respectively, p=0.0388). The post-operative OKS at six weeks was slightly more improved for the femoral nerve block group than for local infiltration analgesia (12.5 vs 9 point median improvements for the femoral nerve block and local infiltration analgesia groups, respectively, p=0.0261). There were no statistically significant differences in other secondary outcome measures. Conclusion A single-shot femoral nerve block significantly reduces the opioid requirement for primary total knee arthroplasty but is otherwise comparable to single-shot local infiltration analgesia.