The patient was admitted with a perforated duodenal ulcer and developed post-operative complications requiring a prolonged stay of 88 days in the Intensive Therapy Unit. She developed restriction of movement in the hip and knee joints bilaterally.
The patient was admitted with a perforated duodenal ulcer and was treated surgically. She had a stormy post-operative period complicated by pneumonia, septicaemia and adult respiratory distress syndrome. She required a prolonged stay of 88 days in the Intensive Therapy Unit, during which time she was artificially ventilated for 70 days. She was then treated in the rehabilitation ward prior to discharge home. It was noticed that she had restricted movements of the hip and knee joints bilaterally. Frontal radiographs of these joints were obtained. These showed peri-articular heterotopic new bone formation.
Heterotopic ossification can occur following a variety of causes, such as local bone or soft tissue injury, total joint arthroplasty, or burns, and around spastic or paralytic joints following central nervous system injury or disorders. Neurogenic heterotopic ossification usually occurs in patients with traumatic brain or spinal cord injury.
It is interesting to note that this patient did not have any evidence of brain or spinal cord injury. However, she was in an iatrogenically induced state of neuromuscular paralysis as part of her treatment in the Intensive Therapy Unit.
The aetiology for the formation of neurogenic heterotopic ossification has not been identified. The peri-articular new bone formation has a predilection for the major synovial joints particularly the hip, elbow, shoulder and knee joints. Peripheral joints are virtually never involved. Joint trauma, surgical stabilisation of fractures and pressure sores in the vicinity are associated with an increased incidence of heterotopic ossification. The ossification is usually between the muscle planes. The time of development is variable and occurs from 2 weeks to 12 months post injury. Time to maturation, which is the cessation of bone growth, is even more variable and is based on radiographic appearance, stabilisation of alkaline phosphatase levels and decreasing or static activity on technetium bone scans.
Radiologically, the three-phase bone scan, using 99m-Technetium methylene diphosphonate, appears to be the best method for early detection, often within 2-4 weeks. Initial radiographs show an indistinct fluffy shadow of ossification, usually by 2 months, which increases in size and then becomes well defined. A well-defined cortex may develop. Computerised tomography (CT) is useful to clearly define the margins, particularly for pre-operative planning.
Management strategies include non-surgical methods of treatment of associated pain, maintenance of joint motion, anti-inflammatory medication such as indomethacin, diphosphonates, and low dose radiation. Surgical resection of bone can be undertaken. The use of adjuvant radiation either pre- or post-operatively has been encouraging in some forms of heterotopic ossification.
The main differential diagnoses would include myositis ossificans where the bone formation is within the muscles. Other disorders that cause calcium deposition in soft tissues are tumoral calcinosis, secondary hyperparathyroidism, gout and pseudogout, para-articular chondroma, calcinosis circumscripta, and hypervitaminosis D.
Neurogenic heterotopic ossification
1. From the anteroposterior pelvic and bilateral knee X-ray images, abnormal calcifications can be seen around the hip and knee joints, appearing in sheet-like or banded distributions. They tend to look “flocculent” or blurred, with local edges gradually becoming clearer.
2. The lesions are mainly located in the soft tissue spaces around the joints, showing calcification or new bone formation. It is not only confined to the muscles but also involves the fascia or intermuscular soft tissue regions between muscle groups.
3. There is no obvious bone destruction or severe deformity of the joint surfaces themselves. However, restricted joint movement is closely related to the formation of new bone around the joints.
4. No obvious fracture lines or large bony defects are observed in the knee or hip joints. The main abnormalities are varying degrees of calcification and ossification within the soft tissues.
Based on the patient's long-term ICU stay, previous neuromuscular blocking agent treatment, new bone formation around the hip and knee joints, and restricted joint mobility, the most likely diagnosis is:
Neurogenic Heterotopic Ossification
1. Conservative Treatment and Medications:
• Pain Management: Nonsteroidal anti-inflammatory drugs (e.g., indomethacin) or other analgesics can help relieve pain and may inhibit further heterotopic ossification.
• Maintaining Joint Range of Motion: Perform passive and active joint mobility exercises within tolerable limits to prevent or reduce joint stiffness.
• Bisphosphonates or Low-Dose Radiotherapy: Depending on the patient’s condition and safety assessment, these options may be considered to suppress ectopic bone growth.
2. Surgical Treatment:
• If the ossification is extensive or severely affects joint movement and causes significant functional impairment, surgical resection may be performed after the ectopic bone matures (usually 12 months or more). Postoperative radiotherapy or continued anti-inflammatory medication may be considered to reduce recurrence risk.
3. Rehabilitation and Exercise Prescription:
• Progressive Joint Mobility Training: Begin with passive range-of-motion exercises, gradually transitioning to assisted active and active exercises. Perform joint mobility exercises 2–3 times per day, each for 10–15 minutes, provided they do not cause significant pain. Gradually increase the range and duration according to tolerance.
• Warm Therapy or Other Physical Modalities: In the absence of clear contraindications, heat or ultrasound therapy can help reduce muscle tension and soften tissue adhesions.
• Muscle Strength and Cardiopulmonary Training: If the patient’s general condition allows, gradually introduce lower limb and core strength exercises and aerobic activities (e.g., seated cycling, swimming or aquatic exercises) 3–5 times per week for 20–30 minutes each session. Increase intensity progressively, guided by heart rate and perceived exertion.
• Individualized Exercise Progression (FITT-VP Principle):
- Frequency: Exercise 3–5 times per week, gradually increasing to a tolerable level.
- Intensity: Start at a moderate level, such as a perceived exertion of about 4–5 on a 10-point scale.
- Time: Each session lasts 15–30 minutes, potentially extending to 30–45 minutes in later stages.
- Type: Begin with active range-of-motion and strength training, progressing to low-impact aerobic exercises (aquatic exercises, cycling, etc.) and ultimately appropriate functional training.
- Volume: Estimate the total exercise volume based on session duration and weekly frequency, adjusting according to individual capacity.
- Progression: Gradually increase repetitions, sets, or light resistance as tolerated without pain or discomfort.
This report is a reference analysis based on the present clinical and imaging data and does not replace an in-person visit or professional medical advice. Patients should make final treatment decisions by considering their actual clinical situation and the recommendations of specialized physicians.
Neurogenic heterotopic ossification
