In June 1999 we instituted a prospective, randomised, double blind study to determine whether in the use of the Profix® total knee replacement system the addition of screws improved the fixation of the tibial base plate. There were 145 arthroplasties in 137 patients, 77% of them female. Their mean age was 66 years. In 86% of the patients there was osteoarthritis and in 14% an inflammatory arthritis. On a random basis, supplementary screws were inserted through the base plate into the tibia in 49% of arthroplasties and the remaining 51% were not fixed. In both groups the postoperative femoral angle measured 95% and at 12-month evaluation the tibial angle measured 89°, giving a total valgus angle of 6°. To date no tibial base plates have come loose. It is felt that the large central titanium peg plays a major role in assisting fixation of the base plate to the tibia and that supplementary screws are unnecessary. There is a small cost saving when screws are not used. We postulate that one may in the future minimise polyethylene debris tracking and osteolysis.

Anterior knee pain after total knee arthroplasty (TKA) occurs in 5% to 30% of patients whether or not the patella has been resurfaced. We retrospectively reviewed our patients, none of whom underwent patellar resurfacing. Only 2% had anterior knee pain, none requiring revision surgery. Our follow-up was between two and five years.

We paid particular attention to removing osteophytes and conducting a thorough peripatellar synovectomy and a circumpatellar cautery denervation.

Our results compare favourably to those in the literature, whether or not the patellae were resurfaced. We conclude that patellar resurfacing in TKA is unnecessary when careful attention is paid to the peripatellar tissues.

Complex acetabular defects after failed total hip arthroplasty (THA) remain a major challenge in revision surgery. We managed 29 patients, of whom 27 had type-III and two type-IV defects (AAOS classification). The mean age of the 16 men and 13 women was 68 years (22 to 96).

Use of a modular uncemented acetabular revision system allowed us accurately to position the construct, and then optimise the orientation of the polyethylene liner in respect of stability in the reduced hip. The modularity of the system allowed good access to do an impaction bone graft to restore the defects in the bone stock. Our follow-up ranged from 2 to 25 months. The orientation of the acetabular construct was measured radiologically and was at 50°. Our complications included four dislocations, two transient nerve palsies, one deep infection, four deep vein thromboses and one death from pulmonary embolism. We conclude that the use of a modular acetabular reconstruction system is promising in these extremely difficult cases.

Resorption of the calcar below the collar of a titanium femoral prosthesis was observed. Biopsies of these lesions showed concentrations of polyethylene. We assessed the size of the resorption and correlated this with the size of the femoral prosthesis and the time since implantation. The age and the weight of the patient were also linked to the size of the prosthesis.

We conducted a finite element analysis (FEA) of the femoral component-femur complex in both the loaded and unloaded situation. The FEA study demonstrated changing pressure under the collar that can be translated into microbending motions, with the degree of the movement dependent on the size of the prosthesis, the material of the prosthesis and the weight of the patient.

We hypothesise that the existence of a ‘polyethylene pump’ due to the bending movements of the collared prosthesis concentrates polyethylene particles under the collar. We therefore postulated that the calcar resorption is due to the polyethylene granulomatous lesions, resulting from the micromotion of the collar of the prosthesis.

We have introduced a radiological scoring system to assess our technical competence in hip replacement surgery. We have also used it to assess the progress of the registrars in our training programme.

This scoring method involves several parameters, including positioning of the components and the quality of interfaces. We compared our results before and after the introduction of this scoring system, and found that the quality of our surgery had improved. We conclude that an objective scoring system is valuable as a training aid, as well as in maintaining standards in our unit.

Over five years, 85 low-cost primary total arthroplasties (Eortopal Bulteamex) were done at a referral hospital. These were followed up for a mean of 48 months (minimum of 18 months). There were 11 revisions (13%), with four (4.7%) necessary for aseptic loosening, two (2.3%) for recurrent dislocations, four (4.7%) for sepsis and one (1.3%) for a periprosthetic fracture.

When these results were compared with the Trent Regional Arthroplasty Register, the revision rate was noted to be four times higher than in the Trent study, with aseptic revisions being twice as high and infection rates three times higher. Dislocation rates were half those in the Trent study. We concluded that our lower dislocation rate probably reflected the quality of our surgery. Our higher sepsis rate was probably related to the hospital environment, and the high aseptic loosening rate due to the quality of the ‘low-cost’ prosthesis.

We conclude that to be cost-efficient, ‘low-cost’ prostheses must be of good quality and that the hospital environment must be optimal. This study highlights the need for an Arthroplasty Register in South Africa.

Between February 2000 and August 2002, 60 Oxford unicompartment knee replacements were done on 51 patients, nine of whom had bilateral surgery. The mean age of patients, 82% of whom were women, was 66 years (45 to 83). Primary osteoarthritis was the pathology in 97% and post-traumatic arthritis in 3%.

The mean range of movement increased from 113° preoperatively to 120° at the most recent follow-up. Complications included one case of deep vein thrombosis, one patient with bilateral tibial component loosening and three patients with loose cement particles in the joint. Most patients have no pain, but some have mild or occasional pain. One patient with bilateral unicompartmental replacements now has lateral knee pain.

Unicompartment knee replacements are an alternative to total knee replacements, but there is a significant learning curve, particularly with regard to cementing techniques. Attention needs to be paid to removing all loose cement from the joint. Patient selection is critical. The complication rate remains low, however, and the results seem satisfactory.

Severe central facture dislocations of the hip in the elderly can be catastrophic. Conservative treatment yields poor results with stiff painful hips. Reasonable hip function may be achieved with multiple surgical procedures and extended periods of immobilisation, but morbidity and mortality remain high.

We managed three elderly patients who had central fracture dislocations with early total hip arthroplasty (THA), using anteprotrusio supports. Bone grafting was used to re-establish acetabular bone stock.

Intraoperatively and postoperatively, these patients had no more complications than did patients undergoing THA for hip fractures. However, the surgical times were longer than for routine THA and blood replacement was slightly higher. Patients were mobilised early and aggressively. All became independent walkers and regained good range of movement. Radiologically the acetabular/pelvic fractures united and good bone-implant interfaces were established. There was no excessive heterotrophic bone formation.

We regard THA in the management of acetabular fractures in the elderly as a reasonable approach, enabling patients to mobilise early and keeping morbidity to an acceptable level.

In June 1999 a randomised double-blind study on tibial base plate fixation was started to determine whether, when using the Profix® total knee replacement, the addition of screws improved the fixation of the tibial base plate. To date 138 total knee arthroplasties (THAs) have been performed, 119 of which were available for study. Selected randomly, 56 patients had supplementary screws inserted through the base plate and 63 did not.

After a minimum of 12 months follow-up, 27 patients had some radiolucent lines at the prosthesis-bone interface on the tibial component. These lines occurred in 14 cases with supplementary screws and 13 without screws. In one patient without supplementary screws, the tibial tray had subsided into the tibia. Statistically there was no apparent difference between the two groups.

The early results of our study raise questions about the value of supplementing base plate fixation in uncemented THAs, especially considering the additional cost of the screws and their potentially detrimental consequences.

Primary total hip replacements are routine procedures with good outcomes. To ensure uniformly good results it is important that a thorough preoperative assessment of the patient is made. The prosthesis best suited to the patient and the pathology must be carefully selected and the optimal surgical technique must take into account patient, pathology and prosthesis parameters.

We discuss patients’ problems such as morbid obesity, the different arthritides and neuromotor abnormalities. Acetabular problems, including dysplastic acetabula and acetabula protrusio, are dealt with in detail. We examine post-traumatic hip pathologies, including retained fracture implants, nonunions and ankyloses. On the femoral side, dysplastic femurs, post-traumatic malunions and post-osteotomies are dealt with.

We have introduced a radiological scoring system to assess our technical competence in hip replacement surgery and the progress of the registrars in our training programme. The scoring method involves several parameters, including positioning of the components and the quality of interfaces.

We compared our results before and after the introduction of this scoring system, and found that the quality of our surgery had improved. We conclude that an objective scoring system is valuable as a training aid, as well as in maintaining standards in our unit.

Resorption of the calcar below the collar of a titanium femoral prosthesis was observed. Biopsies of these lesions showed concentrations of polyethylene.

We assessed the size of the resorption, correlating it with the size of the femoral prosthesis and the time since implantation. The age and the weight of the patient was also linked to the size of the prosthesis.

We conducted a finite element analysis (FEA) of the femoral component-femur complex in both the loaded and unloaded situation. FEA demonstrated changing pressure under the collar. This can be translated into micro-bending, with the degree of movement dependent on the size of the prosthesis, the material of the prosthesis and the weight of the patient.

We postulate the existence of a ‘polyethylene pump’ owing to the bending motion of the collared prosthesis, and that calcar resorption is due to the resultant polyethylene granulomatous lesions .

In a radiological study, we evaluated the outcome of the Chiari osteotomy as a primary method of femoral head containment in a distinct group of patients with Perthes’ disease. Even when Salter’s prerequisites are met, the results of a Salter osteotomy are known to be poor in this particular group of patients.

At the time of operation, the mean age of the 13 patients who underwent Chiari osteotomy was 9 years 4 months. The osteotomy was performed early in the disease process, before femoral head deformity had occurred. The hip was considered to be at risk because of the relatively late onset of the disease. Measurements were made on the preoperative and latest follow-up X-rays, and on the preoperative arthrogram. Patients were followed up for a mean of 3 years 4 months. On the preoperative arthrogram there was no femoral head deformity or hinging on abduction. At the time of surgery, it was too early to assign a hip reliably to a particular lateral or Herring lateral pillar group. However, during the follow-up period, 12 of the hips manifested as Catterall group IV and one as Catterall group II. Further, 11 hips advanced to become lateral pillar type B, and two to become lateral pillar type C. At follow-up, nine hips could be reliably graded according to the Stulberg classification: five were Stulberg type II and four Stulberg type III. It was clear that none of the remaining hips would be Stulberg type IV or V.

The Chiari osteotomy achieves a congruent hip in a specific group of patients where a poor outcome would otherwise be anticipated.

Many authors believe that patellar resurfacing decreases the incidence of anterior knee pain. We analysed the results of 98 of our own patients (103 knees).

Over the past two years, we performed total knee arthroplasty on 23 men (one bilateral) and 75 women (four bilateral). None of the patellae were replaced, but we carefully removed osteophytes, debrided the patella, and performed a thorough peripatellar synovectomy and circumpatellar cautery denervation. All patients on our database were telephoned, and those who reported pain were examined independently by a consultant and a registrar. If there was any controversy about the site of the pain, a third surgeon saw the patient.

No patient had pain severe enough to warrant revision surgery. Only two (2%) had anterior knee pain, and in neither of them was it marked.

We do not know whether our favourable results are attributable to the peripatellar synovectomy and/or circumpatellar cautery denervation. While we concede that a control study of patients who have undergone patellar resurfacing might be necessary before a firm conclusion can be drawn, we question whether, with such a low incidence of patellar problems, this is ethically justifiable.

Among elderly Caucasians, fractures of the femoral neck are a common cause of disability. Intertrochanteric and intra-capsular fractures occur equally often, and both are about three times more common in women than in men. Risk factors include neurological impairment, malnutrition, impaired vision, malignancy and decreased activity.

We found that in black South Africans femoral neck fractures occur equally often in men and in women. Intracapsular fractures are comparatively rare, occurring in one of every eight female patients and one of every 3.5 male patients. Further, we found that in both black men and black women the femoral neck was consistently and significantly shorter than in whites.

These results suggest that a short femoral neck may offer protection not only against intracapsular fracture, but also possibly against fracture of the femoral neck in general. In addition, greater cortical thickness in black people probably offers further protection.

Between January 1990 and October 2000, 108 total hip arthroplasties using a cemented polished titanium stem and a cemented ultra-high molecular weight polyethylene (UHMWP) cup were performed at our hospital. Because during routine follow-up visits we noted instances of resorption of the calcar, we decided to assess whether this was a problem. We were able to assess 85 of the original 108 hips.

Calcar resorption was observed in 43 hips. The extent of calcar resorption varied from 1 mm to over 15 mm. In one patient a biopsy showed typical polyethylene granuloma.

Because there is a risk of long-term failure, we concluded that it is inadvisable to use a cemented polished titanium stem when UHMWP is one of the bearing surfaces.

A nine-year-old girl presented with a four-year history of progressive bowing of the left tibia. She had been seen in our clinic three and four years earlier, when no treatment was advised. She had been complaining of mild pain in the left leg for one month but was otherwise not very perturbed about her deformed leg.

Examination showed bowing of the left tibia, no leg length discrepancy, no limp, and a normal left knee and ankle. Radiological examination showed features of osteo-fibrous dysplasia of the left tibia, with eccentric expansion of the cortex, intracortical osteolysis, marginal sclerosis encroaching on the medulla and diffuse lesional calcification. No other bones were involved.

Because of the progressive bowing of the tibia and the mild pain, the recommended loose observation of the patient was abandoned. Daily treatment with 30 mg IVI pamidronate for three days resolved the pain. One month after the latest presentation the lesion was biopsied. Histological examination confirmed the diagnosis of osteofibrous dysplasia of the tibia. There was no evidence of adamantinoma.

The literature on this rare bone lesion in childhood supports the use of open biopsy if the deformity becomes painful, the bowing is progressive and the patient presents after the age of nine years. Important differential diagnoses include fibrous dysplasia and adamantinoma.