Aims: To study the natural history and treatment of chronic skeletal pelvic pain following childbirth. Methods: 53 patients were studied, of which 13 had surgery to the symphysis pubis (11 fusion, 2 stabilisation). A detailed history was recorded and an examination carried out. Investigations included pelvic X-rays with stress views and MRI of the symphysis pubis in a selected group. Results: Mean age at onset 30.6 years, gestation 39.3 weeks (36–42). 16 of the 17 subsequent pregnancies were associated with recurrence of symptoms. Long term disability showed no relation to type of delivery (p> 0.5). Pain was worse before menstruation. 55% of patients beneþted from conservative management. This did not relate to the site of pain (p> 0.1). Stress views of the symphysis: 39, mean vertical shift 2.2mm. There was no correlation between shift and symptoms. MRI of the symphysis:17, 6 were normal and 11 revealed non-speciþc changes. Surgery:mean age at surgery 34.8 y, time to operation 4.2 y and follow up 23.6 m. Outcome: 7 good, 6 no beneþt. There was a strong reverse correlation between disability and outcome (r=−0.84) while the site of pain had no effect on outcome (p> 0.8). Conclusions: Chronic skeletal pelvic pain following pregnancy is poorly understood and under-diagnosed. It tends to be recurrent and its onset is related to hormonal and mechanical factors in pregnancy. The type of delivery is unlikely to be important although care should be taken with leg and patient positioning. There is no relationship between shift and severity. Conservative treatment is the main standby. Surgery, on the basis of this small study, is useful in those with moderate disability but contraindicated in those with severe disability.

Aims: To evaluate the effect of tapered pegs in reducing tibial tray tilt and subsidence in closed cell foam. Methods: 1. Foam validation was carried out using a load frame (Instron) to establish its static and fatigue behaviour. 2. Subsidence and tilt tests: Three brass peg sets of varying length and matching surface area were designed. Four identical pegs of each set were fixed with screws to an IBII tibial tray and testing was performed using the load frame and the closed cell foam. Results: Foam validation revealed an average strength of 0.65±0.01 MPa in compression and 1.53±0.02 MPa in tension and an average stiffness of 40.2±1.5 Mpa in compression and 50.4±1.06 Mpa in tension. Subsidence tests revealed a significant increase in the total load producing 0.2mm subsidence with pegs ( p< 0.0053) and no significant difference for 1 and 2mm (p> 0.1). Tilt tests revealed a significant increase in the total load producing 0.2mm tilt with the medium and short pegs ( p < 0.008 & < 0.042 respectively) and no significant difference for 1 and 2mm (p> 0.1). Conclusions: The foam analogue material shows similar behaviour to cancellous bone in both static and dynamic tests and suggests that polymer foams are a good analogue material to cancellous bone. The addition of tapered conical pegs to the tibial tray increases its resistance to initial subsidence while initial tilt resistance is increased only with the medium and short pegs. Combining tilt and subsidence resistance, the medium pegs perform most favourably.

Aims: To determine the optimum hydroxyapatite-coating pattern of the femoral component in cement-less hip arthroplasty. Methods: Between January 1996 and May 1997, the þrst 65 patients (73 hips) of a single center prospective trial were randomised to receive a proximally coated Osteonics or a fully coated JRI Furlong stem. 30 Osteonics and 43 JRI stems were implanted. Clinical assessment was carried out using the modiþed Merle DñAubigne and Postel (MDP) system and the visual analogue scale (VAS). Radiological evaluation included measurement of subsidence, bone resorbtion, pedestal formation and implant-bone interface assessment. All live patients were reviewed. The average follow up was 50.3 months in the JRI group and 51.8 months in the Osteonics group. Results: There was one cup revision in both groups for aseptic loosening and one excision arthroplasty in the JRI group for sepsis. Clinical evaluation revealed an MDP of 16.3 (8–18) and a VAS of 0.55 (0–7) for the JRI group. The MDP for the Osteonics group was 16.31 (8–18) and the VAS 0.62 (0–4). Radiological evaluation revealed resorbtion in zone 7A in 16 of the JRI hips and 5 of the Osteonics. There was a reactive line around the distal part of the Osteonics stem in 17 patients, which was not correlated with symptoms. Conclusion: Both hips performed well. There was no difference in revision rate for loosening (p> 0.84). Clinical evaluation showed no signiþcant difference in outcome (p> 0.83). Radiology revealed different patterns, which did not represent a clinical importance at this stage.

Aims: To establish the frequency of achieving the desired prosthesis position in an uncemented total hip replacement and the effect of the position on outcome. Methods: We reviewed the earliest and most recent available post-operative pelvic x-rays of 96 patients who had undergone a total hip replacement between March 1992 and December 1995. A press þt hydroxyapatite coated cup and stem were used in all cases (CSF & JRI respectively). We assessed the following parameters: Centre of rotation, off set, cup angle, leg length and insert wear. We then established the clinical outcome at 5–9 years of 88 patients using the MDP scoring systems and correlated this with the radiological study to establish the effect of prosthesis placement on the clinical outcome. Results: There was an acceptable centre of rotation in 53.6% of the patients, 44% of the patients had a cup angle of 40–49 degrees, 73% had an adequate off set and 71.7% had equal leg lengths. There was no correlation between the MDP and the centre of rotation, cup angle, off set or leg length. There was also no correlation between these parameters and wear of the liner. Conclusion: It is evident that the desired position of the prosthesis is not achieved in a signiþcant number of patients. This does not seem to correlate with the clinical outcome and wear. Extreme deviation from the anatomical position is likely to be detrimental.