Introduction

Accurate acetabular cup orientation could lead to successful surgical results in total hip arthroplasty (THA). We introduce a novel CT-based three-dimensional (3D) planning system, HipCOMPASS (Fig.1) and TARGET (Fig.2), which enable to design suitable alignment not only cup also surgical devices calculatingly, according to each pelvic inclination.

Introduction

Accurate acetabular cup orientation could lead to successful surgical results in total hip arthroplasty (THA). We introduce a novel CT-based three-dimensional (3D) planning system, HipCOMPASS (Fg.1) and TARGET (Fig.2), which enable to design suitable alignment not only cup also surgical devices calculatingly, according to each pelvic inclination.

Prophylaxis against venous thromboembolism after elective total hip replacement is routinely recommended. Our preference has been to use mechanical prophylaxis without anticoagulant drugs. A randomised controlled trial was performed to evaluate whether the incidence of post-operative venous thromboembolism was reduced by using pharmacological anticoagulation with either fondaparinux or enoxaparin in addition to our prophylactic mechanical regimen. A total of 255 Japanese patients who underwent primary unilateral cementless total hip replacement were randomly assigned to one of three postoperative regimens, namely injection of placebo (saline), fondaparinux or enoxaparin. There were 85 patients in each group. All also received the same mechanical prophylaxis during and after the operation, regardless of their assigned group. The primary measurement of efficacy was the presence of a venous thromboembolic event by day 11, defined as deep-vein thrombosis detected by ultrasonography, documented symptomatic deep-vein thrombosis or documented symptomatic pulmonary embolism. The duration of follow-up was 12 weeks.

The rate of venous thromboembolism was 7.2% with the placebo, 7.1% with fondaparinux and 6.0% with enoxaparin (p = 0.95 for the comparison of all three groups). Our study confirmed the effectiveness and safety of mechanical thromboprophylaxis without the use of anticoagulant drugs after total hip replacement in Japanese patients.

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.

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.

We present a series of 30 uncemented total hip replacements performed between June 1985 and January 2002 with a mean follow-up of seven years (5 to 20) in 27 patients who had previously undergone a valgus intertrochanteric osteotomy. No further osteotomy was undertaken to enable hip replacement. We used a number of uncemented modular or monoblock femoral components, acetabular components and bearings. The patients were followed up clinically and radiologically. We report 100% survival of the femoral component. One acetabular component was revised at five years post-implantation for aseptic loosening. We noted cortical hypertrophy around the tip of the monoblock stems in six patients. We believe that modular femoral components should be used when undertaking total hip replacement in patients who have previously undergone valgus femoral osteotomy.

We have investigated the factors which affect the progression of osteoarthritis after rotational acetabular osteotomy (RAO).

Between 1984 and 1998, we treated 60 dysplastic hips by RAO. The mean age at surgery was 31.6 years (13 to 51) and the mean period of follow-up was 4.6 years (2 to 9.5). The thickness of the articular cartilage on the weight-bearing area, pre- and postoperative acetabular cover, and the sphericity of the femoral head were used for radiological assessment.

The osteoarthritis did not progress in 39 hips. Significant factors which affected the radiological grade included sphericity of the femoral head and the postoperative acetabular cover. The surgical approach and preoperative acetabular cover did not affect the progression of osteoarthritis. Patients were divided into two groups according to the surgical approach used, either conventional (23 hips) or modified (37 hips). Significant factors included the postoperative acetabular cover in the modified approach, and the sphericity of the femoral head in the conventional approach.

It is critical that the postoperative cover is sufficient, especially when RAO is carried out using our modified technique.

We carried out a prospective, randomised study of 62 patients to determine the efficacy of a foot sole pump (the A-V Impulse System) for the prevention of pulmonary embolism (PE) after hip surgery. PE was assessed by pulmonary perfusion scintigraphy before and after operation. We defined a PE as any new scintigraphic defect which was larger than a bronchopulmonary segment.

The incidence of PE was 55% in the control group and 21% in the treatment group. The foot sole pump significantly reduced the incidence of PE (p = 0.008) and we encountered no side-effects from its use.