Purpose: The purpose of this prospective work was to determine: 1) the frequency of iliopsoas conflicts with prosthetic acetabular material in patients with a painful total hip arthroplasty, and 2) to determine the diagnostic features of this conflict and the results of an adapted therapeutic approach.

Material and methods: This prospective study was conducted between 1988 and 2000 in 206 painful total hip arthroplasties. Nine patients (4.%), mean age 50 years (38–65) had a highly suggestive clinical presentation (eight press-fit cups without cement, one metal-backed cemented cup). Mean delay to onset after implantation of the total hip arthroplasty was 7.3 months (1–48). The predominant clinical sign was groin pain triggered by active flexion of the hip with pain from 3° to 70°. For these nine patients, there was no sign of loosening and puncture had ruled out infection. The diagnosis was confirmed by sedation of the pain after extra-articular infiltration in contact with the anterior acetabular rim (rim overhang in six out of nine cases) under computed tomographic guidance.

Results: Therapeutic infiltration (xylocaine-slow release corticosteroids) under computed tomographic guidance provided complete sedation in four out of nine cases and partial sedation in one. Four patients experienced recurrence leading to terminal tenotomy of the iliopsoas which provided complete sedation in three and partial sedation in one. In all, seven of the nine patients achieved complete pain relief (four after infiltration including one recurrent case, and three after tenotomy). Physical examination at last follow-up did not disclose any loss of flexion amplitude of the thigh.

Discussion and conclusion: The delay to symptom onset was variable, but a symptom-free interval was always observed after implantation of the total hip arthroplasty. An anatomic factor (anterior cup rim) was not indispensable for diagnosis as it was confirmed in one of three cases with a positive infiltration test without rim overhang. The infiltration test was essential to confirm diagnosis and constituted the first therapeutic attempt which allowed complete cure in four of the nine patients. Tenotomy, indicated in case of recurrence, achieved complete cure in three of the four cases. The cup does not have to be changed necessarily to treat iliopsoas conflicts since infiltration or simple tenotomy provided complete cure in seven out of nine cases.

Purpose: Changes in the lever arm of the abductors is not always perfectly controlled during implantation of total hip arthroplasties. Its possible effect on the development of prothesis dislocation is not known. The purpose of this study was to evaluate the influence of the lever arm and its modifications on the development of prosthetic instability.

Material and methods: We analysed prospectively 73 total hip arthroplasties implanted via the posterolateral approach. The study group was composed of a consecutive series of 45 dislocated prostheses and a control group of 28 stable prostheses selected at random. The following measurements were made on the anteroposterior x-ray: 1) lever arm of the abductors, 2) femoral offset. These measures were compared with the healthy contralateral hip and when this hip was diseased or had a prosthesis, with the pre-implantation x-rays.

Results: None of the studied parameters was statistically different between the dislocated and stable prostheses. However, in the dislocated prostheses, the lever arm of the abductors before insertion of the prosthesis was shorter than in the control group (p = 0.04) suggesting the presence of a group of hips “at risk”. There was a correlation between the offset values and the lever arm values for the stable prostheses and for the healthy contralateral hips in both groups. Conversely, this balance was not found in the dislocated hips. The lever arm/offset ratio was calculated to determine if the ideal ratio influenced hip stability. This ratio was not directly related to the development of dislocation, but it was decreased for dislocated hips. This ratio was ideal for 75% of the stable prostheses and for only 53% of the dislocated prostheses.

Conclusions: We concluded that: 1) hips “at risk” of dislocation would have a shorter lever arm, 2) the lever arm or the femoral offset do not have a direct effect on dislocation, and 3) stable hip prostheses have a balance similar to that in healthy hips identified by a correlation between the lever arm and the femoral offset. We thus emphasise the importance of respecting these parameters although they are probably not the only factors influencing prosthesis stability. Allowable variations are small, demanding careful and precise operation planning.

Purpose: The aim of this study was to follow a prospective cohort of young subjects with total hip arthroplasties (THA) in order to determine 1) how they complied with instructions concerning the surveillance of their implant, and 2) determine factors affecting non-compliance and the potential consequences in terms of wear.

Material and methods: We implanted fifty Harris I cups with the ABG I stem in 15 young men and 24 young women (11 bilateral implantations) between 1991 and 1995. These patients were a non-consecutive prospective series of patients under 60 years of age (mean age at implantation was 38 ± 11 years, range 15–58 years). The ABG I stem was implanted when the femoral canal was cylindrical, other implants were chosen for other morphologies. 28-mm femoral heads were used in 38 cases (30 zircone, 8 chromium-cobalt, polyethylene thickness 8.6 mm, range 8.3–12.4). The patients were informed of the need for regular surveillance with controls at two months, and one year and then every two years. We re-evaluated all the patients again in 2000. Radiographic wear was assessed according to Livermore using a numeric table (OrthoGraphics).

Results: At mean follow-up of 72 ± 14 months (5–9 years), 20 of the 39 patients (25/50 implants) had not attended the intermediary consultations, but all were seen again for the systematic review made in 2000. There was no particular factor related to non-attendance other than male gender (p = 0.04). Wear was rather severe. Mean values were: linear wear 1.32 mm, 0.23 mm/an. Thirty-seven percent of the patients who had severe annual linear wear (> 0.2 mm) had not attended consultations, all were asymptomatic. The 28 mm head produced more volumetric wear than the 22 mm heads (p = 0.008). There was no other factor correlated with severity of wear (age, sex, activity, polyethylene thickness). This systematic revision led to: three replacements due to excessive wear > 2 mm and replacements planned for three others with > 2 mm wear. These six patients were asymptomatic and three of the six had never attended the planned visits.

Conclusion: Despite our recommendations, half of the patients did not comply with the planned surveillance protocol. Non-compliance being inevitable, we recommend regular systematic recalls to detect severe wear early, even in asymptomatic patients. In addition, our study demonstrated that zircone heads contribute little and confirmed the interest of 22 mm heads to limit wear phenomena.