 Question to the discussants: what would be your next step?
Professor Jay V Subbarao
Before we proceed with discussion of management of this patient, we should establish goals for our management plan. I am listing some of them.
- Identify factors that increase the risk of HO formation.
- Establish maturity of HO formation in the right hip and that there are no other active sites.
- Implement preventive measures to minimise comorbidities.
- Enhance patient's rehabilitation potential to enable her to function independently in a community setting.
- Management of mature HO has limited options. Treatment with disodium etidronate (DE) or radiation of mature HO.1 However the latter is not common practice. I will consider a three-phase bone scan even at this stage to rule out any subclinical hyperemia superimposed over the mature HO. If the bone scan reveals increased activity, I will consider treatment with DE for longer duration. It appears that this patient has previously responded favourably for medication management for the lesion on the right thigh.
- Surgery for HO We reported good outcome from wedge resection of HO at the hip but the indication was primarily to enable the patient to be able to sit in the wheelchair.2 Wide resection of HO often leads to extensive bleeding, wound infection, prolonged immobility and in rare instances necessitates hip disarticulation or higher level amputations. We recommend that treatment with DE be continued post operatively until there is no clinical activity or indicated isotope uptake in the bone scan. Postoperative plain radiographs always show new bone formation but that by itself does not suggest recurrence.
- Seating System This patient's seating system should be reassessed periodically and a custom moulded insert with partially reclining back may improve her posture in the wheelchair. However, the wheelchair propulsion from this position is not very energy efficient. Proper posture maintenance is critical for prevention of pressure ulcers and spinal deformities.
- Spasticity The relationship between spasticity and HO is well documented. While direct contribution of spasticity in HO formation is not established, recurrence and severity of HO in patients with severe spasticity is reported. As such we should closely modulate the spasticity management in this young lady.
- Seizure The etiology of seizure (fit) in this otherwise healthy young individual needs to be identified. With the history of sudden onset epidural hematoma and seizures, multiple AV malformations should be ruled out. The seizures will add additional limitations in function and social reintegration for this young girl. For example driving restrictions and participation in recreational activities. If necessary she may need ongoing medication management for seizure control.
- What could have been done? There are reports of HO control with DE therapy orally and or intravenously.3 Similarly low dose radiation has been reported to control HO and avoid recurrence following surgery. We have not recommended prophylactic DE therapy for individuals with SCI for prevention of HO. We experienced good results with early intervention by way of medication management and joint mobilisation. We depend on the three-phase bone scan to monitor the progression of HO and increased vascularity. We initiate passive range of movement exercises within 2 weeks after starting therapy, while avoiding forcible stretching to minimise clinical or microscopic haemorrhage, which can lead to new HO formation. Judicious range of movement in the early stages of HO may enable the patient to retain function in the involved joint even though there is radiological evidence of massive HO formation.4 We have reported two cases with pseudoarthrosis in HO and the patient retained function of the joint involved in spite of extensive HO formation.5 I do not have experience with management of patients with radiation because it is not commonly used in our centre. I have not recommended manipulation of the involved joints in the SCI patients because they are at a high risk for pathologic fracture.4
Professor Kresimir Banovac
As a next step in the treatment of this patient I would recommend surgery. We do not have medication to treat heterotopic ossification (HO) at such late stage of development. The only treatments available today are for early stages of HO formation after SCI.
It is important to emphasise that this patient will need medical treatment after surgery to prevent regrowth of HO. Although there is no accepted protocol for postoperative prophylaxis after HO removal, on the basis of our present knowledge about this condition, the most acceptable protocol would be:
- First use NSAID's alone and
- Later add etidronate.
In the general population NSAIDs significantly reduce the incidence of HO after acetabulum fractures and total hip replacement.6 Similarly NSAIDs given early after SCI reduce the incidence of HO.7
I would recommend using indomethacin SR 75 mg in the first 6 weeks after surgery, or one of the COX-2 inhibitors for the same period of time. The effect of etidronate would be on the bone forming cells - osteoblasts that `escape' from inhibitory action of NSAIDs. The addition of etidronate would inhibit mineralisation of the bone matrix. Again, there is no protocol for postoperative use of etidronate, but one could start administration 2 weeks following surgery for a period of 3 months at a dose of 20 mg/kg/day. This approach has been effective in some of our patients.
Mr WS El Masry
This most unfortunate young lady sustained double jeopardy, the first being a non traumatic paraplegia of vascular origin over which she had no control. Secondly, massive heterotopic calcification of the iliopsoas muscle, the size and effects of which could have been minimised.
There is no easy way to manage this girl's problem, however, I will tentatively describe the rationale of the management, the main goals of her management and the sequence of investigation and treatment procedures to achieve them.
In my opinion no effort should be spared in trying to achieve comfortable seating in a wheelchair. In order to achieve this she will need to be able to flex her hips and her knees to 90 degrees. She should also be able, when lying in bed, to lie comfortably including in the supine position. In order to achieve this she should be able to have both her hips and knees extended.
From the scans available, it appears that the heterotopic calcification affects mainly the iliopsoas muscle. Although this muscle is a hip flexor, this patient's disability is caused by her inability to flex the hip. This hip extension deformity could be accounted for by one or two mechanisms. The most likely is that because the iliopsoas muscle is completely calcified (which must have happened during bedrest, probably in the supine position with extension of the hip), the calcified iliopsoas is acting as a rigid splint preventing flexion of the hip. The other possible but less likely mechanism could be excess spasticity of the hip extensors.
My first line of investigation would be to assess how much of the deformity is related to spasticity of the hip extensors and how much is due to the heterotopic calcification of the iliopsoas muscle.
In order to adequately establish which mechanism is involved, the patient will require a general anaesthetic. Manipulation under anaesthesia should also be attempted at the same time. Under the same anaesthetic the range of movement in the knee and ankle joint should also be assessed.
In the likely event manipulation of the hip does not result in adequate flexion, I would proceed to carrying out surgical debulking of the iliopsaos muscle. The patient will require biphosphonate as well as non-steroidal anti-inflammatory drugs for a least a year following the procedure. The patient ought to be aware that this is likely to be a difficult operation and that she may require blood transfusion because of the likelihood of bleeding during the surgical procedure. Post operatively an intensive rehabilitation programme will be required in order to prevent recurrence of the deformity by unopposed spasticity of the hip extensors.
In my opinion no effort should be spared in trying to achieve for her comfortable seating in a wheelchair.
Susan B Bergman
The issue of heterotopic bone formation in a growing child with a spinal cord injury is a complex one. Certainly, a fixed hip deformity will add to the risk of progression of her scoliosis. As the physical therapists have noted, it will also affect her seating position and limit her wheelchair mobility.
I am not sure if the initial course of etidronate included any non-steroidal anti-inflammatory agents along with it. If not, a place to start would be a trial of indomethacin along with the etidronate.
The next step would be to assess the metabolic activity of the heterotopic bone. This is important in assessing whether she is a candidate for excision of bone mass. If the bone is metabolically active then the risk is of actually increasing the bone after a resection. Metabolic activity of the bone mass can be assessed by checking serum alkaline phosphatase levels as well as obtaining triple phase bone scan.
If the bone is no longer metabolically active, then she may be a candidate for surgical resection of the heterotopic bone, especially because it bridges the hip joint and limits her seating and mobility. She should also be evaluated by a radiation specialist to see whether pre or post operative radiation might be helpful to shrink the mass.
Mr F Jamil
It was becoming increasingly obvious that the scoliosis was rapidly moving from flexibility in the recumbent decubitus position to non-flexibility within less than 9 months of the onset of paralysis. In addition, after discussion with the therapy team it was believed that no further therapy was going to be effective without restoring some form of flexibility to the left hip joint. It was therefore agreed by the whole team, by the patient and her relatives that we could not wait for the full maturity of her left hip HO before tackling the problem surgically.
The surgery was carried out through a boomerang incision 2 cm above and parallel to the inguinal ligament from just above the anterior superior iliac spine to 2 cm lateral to the pubic tubercle and curving down vertically for about 10 cm in the middle of the femoral triangle. The key to the surgery was exploration of the bulk of the ossified mass, which was largely in the region of the iliacus and extended down and parallel to the psoas muscle, and tapered about 4 cm below the anterior capsule of the hip joint. This was achieved by dividing the inguinal ligament and the internal oblique and transverse muscles that originate from the outer third of the inguinal ligament, and ligation of the deep circumflex iliac artery. This allowed for extra-peritoneal exposure of the whole mass by retracting away the peritoneum supero-medially. The femoral artery was isolated on vascular slings for continuous identification. All tributaries arising from the femoral artery and going in the direction of the mass were ligated. As it was impossible to access the deep feeding vessels to the bony mass, the decision was made to de-bulk it first from the inside which was achieved by excising of anterior periostium and continually removing the ossified tissue from the mass until the entire ossified mass was removed from the side wall of the ilium and the front of the left hip joint. On completion of the mass removal the posterior periostium of the mass was excised relatively easily and all the posterior feeding vessels were identified by putting some degree of traction on the edge of the periostium. There was a clear demarcation zone between the posterior periostium of the mass and the anterior hip joint capsule. The heterotopic ossification surrounding the upper third of the femur was not disturbed as, on completion of the excision of the cephalad mass it was possible to flex the left hip to 120 degrees on the operating table. The total blood loss was approximately 1200 ml. Her post-operative course was extremely smooth with no wound complications. Passive movement of the hip joint was carried out throughout the healing period. Three weeks following the surgery the patient was put in a specially moulded orthosis and was transferred into a wheelchair where she was able to bend forward, and also pick up objects from the floor.
Disodium etidronate was continued for approximately 6 months following surgery. A post-operative follow-up of more than 2 years indicated no further recurrence of the HO (Figure 5a-e). No post surgery irradiation or either pre or post surgery NSAID's were used.
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