Surface arthroplasty in a cerebral palsied patient with hip dysplasia and dislocation

Introduction

Cerebral palsy is a syndrome caused by a non-progressive upper motor neuron lesion, originating before the central nervous system is mature. Patients suffer abnormal control of motor and sensory function and sometimes abnormal intellectual development. There are different etiological factors but perinatal anoxia is one of the most common. The spastic type is the most frequent and is characterized by rigid muscles with an inability to relax that produces a variety of anatomical and clinical signs. The incidence of hip dysplasia is very high in these patients, including adduction contractures, increased femoral anteversion, coxa valga and acetabular dysplasia. Pain is highly associated with these abnormalities and up to 50% of patients have hip dislocation¹. A dislocated painful hip in a patient with cerebral palsy can be treated by muscle releases, femoral or pelvic osteotomies and reduction, Girdlestone, arthrodesis or total hip arthroplasty^1,2. In a young patient with a good quality of life who was previously able to walk, we think that the best option is a total hip arthroplasty^1–4 in order to relieve pain, allow perineal care and facilitate mobility and the ability to walk independently.

Case report

In 2011, a 15-year-old boy, Caucasian with triplegic cerebral palsy came to the clinic in a wheelchair, accompanied by his family. He complained of intense pain in his right hip that had been increasing over the last years. Unfortunately, the pain had translated to poor function. He had sparing of his upper left extremity of the hip. He described his hip function as limited and poor, and as continuously worsening. He tried not to bear weight on his right leg, although he was still able to walk around and transfer himself, usually with a Kay posture walker, in his house and around a baseball field.

In addition to the pain, he also had a history of right hip subluxation. Ten years previously, he had bilateral hip soft tissue and muscle releases, and osteotomies which were varus producing. Four years before, he had spinal fusion to help his alignment, and that did seem to help him to some degree. At that point his doctors noticed that his hip was coming out of the socket. His parents were very fearful of him losing his hip functionality as they saw that it had been getting worse in the four years after the spinal fusion. They had seen other doctors who had recommended Girdlestone rather than total hip replacement.

Subsequent X-rays demonstrated hip dysplasia and a dislocated joint with bowing of his femur in the subtrochanteric area. The head was completely out-of-round (Figure 1). The patient also had mild mitral regurgitation and suffered some spasticities whilst on a baclofen pump.

Figure 1. X-ray showing a dislocated and dysplastic joint.

On physical examination he had some spasticity in his lower extremities and very limited movement of his right hip mainly because of pain. His muscle strength was 4/5 in the right leg. His adductor tendons could be felt but they did not seem overly tight.

At this point, total hip replacement was recommended, and the family were informed that he would most likely require subtrochanteric osteotomy, realignment of his femur, placement of a modular-type implant, formation of a new socket and soft tissue releases.

During the reviewing and planning of the case and surgery, we thought about the possibility of implanting a resurfacing hip prosthesis with the idea of maximizing the benefits of this type of device in our patient. Doing so would decrease the duration of the surgery and we wouldn’t need to perform an osteotomy on the femur with consequent lower blood loss and reduced perioperative risks. Also we could achieve the best intrinsic stability and maintain as much proximal femoral bone stock as possible. In addition, the bearing surfaces were perfect as he was a very young patient. Our main concern was the durability of the replacement in terms of loosening or fracture.

The family and the patient were carefully informed about the pros and the cons of both surgical options and they accepted our indication of hip resurfacing rather than conventional hip replacement.

The surgery was conducted in the usual manner, approaching the hip posteriorly without any special issues. The new hip was relocated, moderate soft tissue release was realized and intraoperative regular mobility and stability were accomplished. Postoperative X-rays demonstrated that the implants were well positioned and normal anatomy was almost perfectly recovered (Figure 2 and Figure 3).

Figure 2. Postoperative X-ray showing correct implantation and reduction on the hip.

Figure 3. Postoperative X-ray showing correct implantation and reduction on the hip.

Four to five days following surgery, the patient started walking and was put on physical therapy in the typical time and fashion. He had to use an abduction brace for 6 weeks post-surgery. He recovered well but slowly.

At a follow up one year after surgery, the patient was pain-free, walked with a one-handed assist, played without restrictions and had recovered a very good functional status. The passive range of motion in his right hip was much better than it was preoperatively, allowing him to sit and facilitating perineal care. His improvements had been very slow but his gait was still getting better each day.

The two main goals for our patient, pain relief and functional improvement, had been achieved.

Discussion

Total hip replacement is currently a common procedure used to manage painful hips in patients with arthrosis and dysplasia^3,5–10. Cerebral palsy, even in the presence of hip dislocation, must not dissuade the surgeon from performing this procedure, especially in ambulatory patients^4,5. Resurfacing hip prosthesis is a type of hip replacement that should be considered in these patients because of its benefits in terms of stability⁵, preservation of bone stock and low wear expectations^5,11. The presence of femoral deformities could be considered as a relative contraindication for resurfacing of the hip⁹, but in some cases the surgeon should consider that hip resurfacing avoids the difficulty sometimes encountered in patients with dysplasia during total hip replacement of a narrow and frequently curved proximal femoral canal⁶. The survivorship of this implant at five years in patients with different levels of dysplasia is similar to the rates for total hip replacements, always above 95%^6,7. The clinical outcomes of resurfacing with respect to pain scores, restoration of the joint biomechanics, range of motion and walking and sport activities are also very good at five and ten years^2,4,6,8,9; even some measurements such as range of motion can be better after hip resurfacing than after total hip replacement⁷. Furthermore, there is the possibility of an easier conversion to a total hip arthroplasty if needed.

There are no reports about the use of hip resurfacing in cerebral palsied patients but considering that these devices have demonstrated good results in dysplastic hips, we think that cerebral palsy may not be a complicating factor and the results or resurfacing could also be comparable to those obtained in not palsied individuals with dysplasia. For instance, it has been shown that other procedures such as acetabuloplasty, pelvic osteotomies and femoral osteotomies with or without open reduction of the hip have similar outcomes in patients with and without cerebral palsy³.

Further studies will be needed to demonstrate conclusively that resurfacing is as valuable as total hip replacement in the majority of cerebral palsied hips.

Consent

Written informed consent for publication of their clinical details and clinical images was obtained from the patient and his parents.