Rare case of a traumatic myositis ossificans in the tibialis anterior muscle

Discussion

As mentioned before, MOT is a common manifestation after an injury or contusion in the proximal extremities. Hyder et al reported in 1996, as first and only, a case of myositis ossificans which involved the entire anterior and part of the deep posterior compartments of the lower leg after an ischaemic injury.14 However, this was not a traumatic event.

Multiple imaging techniques can be used to confirm MOT and to exclude a neoplastic origin. Immediately after the injury, CT is the best imaging technique to visualise the lesion before the calcification can be seen on X-ray.3 15 This calcification is not immediately visible, because early in the disease course the lesion mainly consists of cellular tissue with (myo) fibroblasts resembling granulation tissue.15 16 Then, 2–6 weeks after the injury, a lucent central zone can be seen on plain radiographs as well as a well-defined peripheral cortex. After 6 months, the lesion can be recognised by a circumferential calcification parallel to the shaft of long bones which is separated from the original bone by a radiolucent cleft, called the ‘string sign’.15 17 18 CT is the imaging technique of choice, because especially the progression of MOT can best be evaluated with a CT scan. At first, a soft tissue swelling without calcification is visible immediately after the traumatic event. Then, 4–6 weeks after the injury, the characteristic peripheral calcification pattern or ‘string sign’ is visible.19 20 Moreover, CT is the best option for follow-up and for distinguishing myositis ossificans from osteosarcoma by visualising specific zonal patterns.3 15 In MOT, the first peripheral zone consists of well-organised mature lamellar dense bone. The second or intermediate zone consists of osteoid, and the third central zone consists of an immature non-ossified cellular focus.17 21 Opposite to MOT, in osteosarcoma, the most dense ossification is located centrally.17 21 Another imaging technique that can be considered to visualise myositis ossificans is bone scintigraphy. It is a sensitive but non-specific tool to diagnose calcified soft tissue mass, characterised by increased uptake in the early stages, which progresses to normal uptake when the bone is matured.15 22 Bone scintigraphy is only taken into consideration when surgical resection of the lesion might be necessary, to determine the appropriate timing of surgical intervention. If serial bone scans are made and show progressive decrease in radiotracer accumulation, this is a sign that the disease becomes inactive.7 15 22 Finally, MRI is only useful in detecting acute lesions, including bone marrow oedema, periostitis and reactive joint effusions until 8 weeks post-trauma, but not in detecting the specific calcification that characterises myositis ossificans.15 18 Once the lesion is matured, ultrasound can demonstrate a complete, highly reflective calcified periphery.8 15

From a preventive perspective, multiple studies have researched the effect of radiation therapy, non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin on the formation of MOT. Evidence shows that both NSAIDs and single-dose irradiation are effective in preventing HO after total hip arthroplasty (THA).19 23 24 Radiation therapy is proven effective in a 7G single dose, but it is expensive and may be accompanied by adverse side effects, which is why it is not a preferred preventive measure. NSAIDs are often administered in already diagnosed MOT, although their efficacy has never been researched. Yet, they are widely investigated and used in the prevention of HO after THA, hip arthroscopy and HO resection.19 23–32 NSAIDs are divided into non-selective and selective COX inhibitors. Indomethacin is most frequently investigated, although naproxen and diclofenac seem to be equally effective in the prevention of HO.28 31 The preventive mechanism of NSAIDs on HO is based on inhibition of prostaglandin production and possibly the favourable differentiation of preosteoblasts.9 19 28 Recently, a meta-analysis by Kan et al showed that NSAIDs could decrease the incidence of HO after THA, regardless of what kind of NSAIDs (selective vs non-selective) were taken.24 The authors concluded that celecoxib showed significantly fewer side effects and a lower rate of discontinuation compared with indomethacin. However, since published data have demonstrated that the use of celecoxib could induce an increased cardiovascular risk and morbidity, the use of celecoxib is limited.19 23 24 28 31 When indomethacin is started, 25–50 mg two to three times per day for 7–11 days is the recommended dose.13 28 31 33 The effects of aspirin on the prevention of HO after THA are unclear. Neal et al performed a large randomised controlled trial that showed no significant effect of low dose (162 mg/day) aspirin versus placebo in the prevention of HO after THA.34 Whereas Cohn et al found a significant decrease in the occurrence of HO by aspirin users (325 mg/day) versus warfarin users.35

Thus, taken the abovementioned studies into account, one could advocate prescribing NSAIDs as a preventive measure for MOT. Naproxen, ibuprofen and indomethacin could all be prescribed, but indomethacin is the preferred medicine, as this NSAID is most extensively studied with regards to HO.9 23 28 Finally, no clear conclusion can be drawn with regards to the use of aspirin in the prevention of MOT, because no consensus has been reached yet.

The lack of evidence regarding prevention of MOT almost equals the scarcity of literature about the treatment of MOT. In 35% of the cases, MOT is self-limiting and the lesion will spontaneously regress in 1–2 years, which is why it is preferred to treat it conservatively.3 4 Since no scientific evidence shows that a benign lesion such as myositis ossificans can alter into a malignant osteosarcoma, treatment is only reserved for symptomatic lesions.17 It is recommended to start with rest, ice, compression and elevation (RICE) in the first 24–48 hours post-trauma.3 7 16 30 Current conservative treatment options are physiotherapy, sometimes in combination with extracorporeal shockwave therapy (ESWT) or acetic acid phonophoresis. Surgical resection is only indicated when neurological or vascular tissue is compressed or when the pain or limited ROM continues after 4–6 months conservative treatment.3 5 7 13 30

Ryan et al developed a three-phase rehabilitation programme in 1991 that was updated by Larson et al in 2002, aimed at recovery from thigh muscle contusions that could eventually develop in MOT.7 13 This three-phase rehabilitation programme consists of the first phase in which RICE is applied to limit the haemorrhage. Also in this first phase, mobilisation exercises of the hip and knee are executed. These exercises should be carried out without experiencing any pain. When no pain is experienced in this first phase, the second phase is initiated. In this second phase, RICE is continued if necessary, combined with active knee flexion exercises until 120°. Again, when no pain is experienced in this phase, the third and last phase of the rehabilitation programme starts. This last phase consists of low-intensity exercises, such as cycling, swimming, walking and jogging to regain normal movement patterns and to avoid reinjury.7 This phase is followed by sport-specific activities and return to play as soon as possible. The programme was successfully executed once a day with mild to moderate contusions and two times a day with severe contusions in cadets, football players and ice-hockey players.7 13 36 According to Danchik et al, soft tissue manipulation, passive exercises and active stretching are advised, but they should not be started too early in the rehabilitation process.37 However, Miller et al concluded that 1–2 weeks rest deconditions the athlete too much, hence they recommend to already start stretching the muscles in the pain-free zone, supervised by a trained therapist in the first 2 weeks post-trauma.33 Also, static or contract–relax flexibility exercises and strengthening exercises are advocated.20 33 38 39 The strengthening exercises should be focused on the muscles around the lesion, since these muscles are most likely to be weakened. The strength exercises should be gradually built up by starting with no or low-load isometric exercises, followed by heavier concentric and eccentric exercises.33 Furthermore, proprioceptive exercises should be carried out, because the intramuscular neural elements that provide muscle tone might also be damaged by the injury.33 In accordance with Ryan et al, Miller et al suggest that as soon as the athlete is able to tolerate the exercises without any pain or reports, sport-specific exercises can be initiated in order to return to play as soon as possible.33

Recently, a prospective case study was performed by Buselli et al in which 24 male (sub)elite athletes diagnosed with post-traumatic MOT in the anterior thigh or upper arm were treated with RICE and aspirin or indomethacin, combined with daily ultrasound therapy and physiotherapy.21 The physiotherapy programme consisted of passive stretching, manual and mechanical passive mobilisations and exercises. After 4 months, three ESWT sessions were added, and the physiotherapy programme was extended with active mobilisation, proprioceptive exercises and isometric, isotonic and eccentric exercises in closed and open kinetic chains. Results showed that no significant improvements were experienced after solely physiotherapy, but combined with ESWT there were statistical significant improvements in the experience of pain and ROM. The authors concluded, based on these results, that physiotherapy should be combined with ESWT to successfully rehabilitate from MOT. However, the major limitation of this study is the absence of a control group.19 Another study carried out by Torrance et al described a case report of a 20-year-old elite rugby player diagnosed with MOT in the anterior thigh who also received three ESWT sessions combined with an unsupervised exercise programme with stretching, strengthening and balance exercises.2 After 2 weeks, the patient experienced less pain and an improvement in ROM. Four weeks after the first treatment, he was able to return to play.2 The hypothesis that ESWT could be beneficial in the treatment of myositis ossificans could be further reinforced by the study carried out by Vannini et al who described a positive effect of ESWT in the treatment of HO.40 Another treatment option that might be useful in the treatment of MOT is acetic acid phonophoresis. Bagnulo and Gringmuth present a case series of three patients diagnosed with post-traumatic MOT in the thigh.5 In this study, the effect of acetic acid phonophoresis (three times a week for 4 weeks) in combination with exercise therapy was examined. Results showed that although the size of the calcification only decreased in two out of three patients, all patients experienced less pain and improvement in ROM and were able to return to play.5 These results were similar to those of Gard and Ebaugh who successfully performed acetic acid iontophoresis and physiotherapy with active ROM exercises in a 19-year-old hockey player with MOT on the upper arm.41 The hypothesis about acetic acid iontophoresis was based on the idea that the acetate ion in acetic acid reduces the size of calcium deposits through absorption due to the negative polarity of the acetate ion.5 Although evidence is scarce, acetic acid phonophoresis might contribute to the recovery of MOT.

As already mentioned above, surgical resection is only reserved for patients with persistent pain and limited ROM, or with compression of vascular or neurological tissue. However, if surgical resection is needed, it is recommended to start postoperative treatment with NSAIDs for 6 weeks in combination with the three-phase rehabilitation protocol of Ryan et al.13 Contraindicated treatment options are deep tissue massage and heat therapy. Scientific evidence shows that deep tissue massage and heat therapy contribute to the aggravation of myositis ossificans, because the heat and deep tissue massage stimulate the circulation, whereby the haematoma and the lesion grow.1 5 7 11–13 36