RECOVERY AFTER THREE DIFFERENT TECHNIQUES IN MINIMALLY INVASIVE TOTAL HIP ARTHROPLASTY

Abstract

There are several techniques in minimally invasive total hip arthroplasty. One of the possible advantages of these techniques is early functional recovery. The purpose of the study was to evaluate possible differences in functional recovery patterns after three different techniques of minimally invasive total hip arthroplasty.

Patients and methods: Two hundreds and eighty-eight hips were recruited for this study. All operations were done without cement in all institutes. Acetabular components were Trilogy and femoral components were VerSys (Zimmer, Indiana, USA) in all hips. Mini-incision antero-lateral approach was used for 112 hips (Mini-AL group), mini-incision postero-lateral approach for 53 (Mini-PL group), and muscle sparing antero-lateral approach was used for 123 hips (MS-AL group). There were no significant differences among the three groups for age. All patients were encouraged to walk with full weight-bearing as soon as possible. Early functional outcome was assessed by the attainment of functional milestones, including the number of days post-op to walk 100m with a T-cane and to put on socks. We also analyzed pain during resting and walking, and evaluated muscle strength for abduction before surgery, at one, three, five, seven and 14 days after surgery. Pain was assessed using a visual analog scale. Muscle strength was assessed using a hand held dynamometer (MicroFET-2) in supine position. The post-pre-operative strength ratio was calculated and defined as the recovery ratio. For continuous variables, a Kruskal-Wallis test was used. For comparison among all three groups, the level of significance was set at p< 0.05. For the three multiple comparisons, the level of significance was calculated using the Bonferonni adjustment and was set at p< 0.0165.

Results: Mean of the post-op days to walk 100 meters with a T-cane was 4.09 days for MS-AL group, 4.82 for Mini-AL group, and 5.57 for Mini-PL group. MS-AL group showed a significantly earlier recovery than Mini-AL group. Mean of the post-op days to put on socks was 5.86 days for MS-AL group, 7.37 for Mini-AL group, and 9.9 for Mini-PL group. MS-AL group showed a significantly earlier recovery than Mini-AL and Mini-PL groups. There were no differences for resting pain or walking pain at any days among the three groups. There were no differences for recovery ratio of muscle strength for abduction at 3 postoperative days. At 5 days, Mini-AL showed a lower ratio than MS-AL. And at 7 and 14 days, Mini-AL showed a lower ratio than both the MS-AL and Mini-PL group.

Conclusion: Muscle sparing antero-lateral technique showed earlier recovery for walking and putting on socks than those using mini-incision techniques.