Purpose of study: Sixty four patellofemoral (PF) arthroplasties in 48 patients were evaluated to assess the effectiveness of this procedure in patients with a preoperative diagnosis of patellofemoral osteoarthritis.

Methods: All patients who underwent patellofemoral arthroplasty for patellofemoral osteoarthritis between 1992 and 1998 in two district general hospitals were studied. Three authors not directly involved in the patients care assessed the patients by:

both a modified Hungerford and Kenna knee rating system and Insall and Crosby grading system, and

Results: Preoperative diagnosis included 53 patients with primary PF arthritis, 1 with post-traumatic arthritis and 1 with PF osteoarthritis secondary to recurrent subluxation. The average patient age at surgery was 73 (range 42–89) and the average length of follow-up was 41 months (range 6–90 months).

Preoperatively 17 knees had undergone arthroscopy. 36 Lubinus, 17 Cartier and 2 PFV prostheses were used. 5 patients died with 8 PF arthroplasties in situ, 1 patient lost to follow up (these patients are not included further in the analysis). 48 Patellofemoral arthroplasty knees were reviewed. 38 knees were classed as good or excellent, 10 had unsatisfactory results, and 7 were revised. 5 implants were revised to TKR and 2 were revised to PF arthroplasty (for maltracking). Subjectively 41 patients felt they were better, 5 unchanged and 2 worse.

Overall we had 69% good or excellent results, 18% poor, and 12% revised. There were no infections, no revision for loosening, and no documented difficulty in revisions. The worst results were obtained in patients with evidence of tiblo-femoral OA preoperatively and in patients with tracking problems.

Conclusion: PF arthroplasty is technically demanding. Nevertheless, providing one adheres to strict patient selection criteria, and the surgery is performed by a dedicated specialist knee surgeon, PF arthroplasty may be used to treat proven isolated patellofemoral arthritis.

Pyomyositis is rarely seen in temperate climates. Typically, it presents with the formation of an abscess requiring surgical drainage and it has been reported as a differential diagnosis for septic arthritis of the hip.

We describe the occurrence of pyomyositis of the iliacus muscle in a ten-year-old girl which was diagnosed by MRI and blood culture. Formation of an abscess did not occur despite marked focal inflammation and swelling of the muscle. Conservative treatment with antibiotics alone led to complete clinical and radiological resolution of the infection.

We could find no previous description of pyomyositis in a child in the British orthopaedic literature. Orthopaedic surgeons, particularly those with a paediatric interest, should be aware of this condition and its presentation, diagnosis and treatment.