Patients with Neuromuscular disorders who have an arthritic hip joint present unique challenges. Due to inadequate bone stock, bony deformity and muscle imbalance there is a potentially increased risk of dislocation. These patients who have undergone conventional total hip replacement in the past, have been immobilised post-operatively in a hip spica to prevent post-op dislocation. Large heads are inherently more stable and adequately treat these patients, without the need for post-operative immobilisation.

We present our experience with large head replacement in this group of patients. Eight patients, five with cerebral palsy, two with Down’s Syndrome and one with Cornelia de large Syndrome, who underwent total hip replacement with a large head prosthesis were reviewed. Their average age was 44.5 years and patients were followed up for maximum 51 months. Patients were assessed with respect to pre- and post-op pain, mobility and function. Hip scores have not been found to be useful in assessing these patients.

Two Birmingham Surface replacements were used and six large heads on conventional stems, with large uncemented cups. In all patients there was improvement in pain and function. Four patients had improvement in their ambulatory status. In none did this worsen. Despite no post-operative immobilisation, there was only on dislocation. This was due to error in cup positioning, an error in the early learning curve.

Despite the small numbers and short follow up, we feel that large head replacement is a viable alternative to conventional hip replacement in these difficult cases.