Osteomyelitis of the humerus following steroid injections for tennis elbow

S. Jawed and S. A. Allard

Department of Rheumatology, West Middlesex University Hospital, Twickenham Road, Isleworth, Middlesex TW7 6AF, UK

SIR, Soft tissue rheumatism is a common clinical problem for rheumatologists. Presentations such as tennis elbow, plantar fasciitis and shoulder capsulitis all respond well to local steroid injection, which is a relatively safe procedure and is usually free from serious side-effects. Here we present the extremely rare but important complication of osteomyelitis following steroid injections for tennis elbow. Osteomyelitis after soft tissue injection in a rheumatology setting has been reported previously after steroid injection for plantar fasciitis [1] and subacromial bursitis [2] but this, to our knowledge, is the first report of this complication after steroid injections for tennis elbow.

A 51-yr-old female insurance broker presented to her primary care physician with right lateral epicondyle pain of several weeks' duration, which was exacerbated by wrist extension. A clinical diagnosis of tennis elbow was made and the patient was treated with a local injection of hydrocortisone into the tender area overlying the lateral epicondyle. There was only a partial improvement in symptoms, and the patient was then referred to a musculoskeletal physician. The initial diagnosis was confirmed and a second hydrocortisone injection was given 3 months after the first one. There was little improvement and a third hydrocortisone injection was given 2 days later. The patient subsequently reported an increase in symptoms with localized pain, swelling and erythema that failed to resolve after several days. A provisional diagnosis of localized soft tissue infection was made, and the patient was treated with two 5-day courses of tetracycline (the patient was allergic to penicillin). Six weeks later she was referred to our outpatients department with a painful right elbow, which she was unable to extend. On clinical examination there was localized swelling and tenderness around the lateral epicondyle with the elbow held in 20° of flexion. Routine blood tests showed a white cell count of 10.5 x 109 per litre, erythrocyte sedimentation rate of 10 mm/h, C-reactive protein of <4 mg/l (normal range <4 mg/l) and negative blood cultures. A plain radiograph of the elbow showed a small joint effusion and soft tissue swelling at the lateral epicondyle. An ultrasound scan confirmed the effusion and showed an abnormal signal in the soft tissue overlying the lateral epicondyle. This was followed by a radioisotope bone scan, which revealed increased tracer uptake in the lateral aspect of the distal humerus, suggestive of osteomyelitis. This diagnosis was supported by an MRI scan of the area, which showed a small joint effusion and increased signal in the lateral epicondyle of the humerus and adjacent high signal in the subcutaneous fat (Fig. 1Go). These findings were all consistent with a diagnosis of osteomyelitis and the patient was treated with a 6-week course of clindamycin 300 mg four times per day. There was a complete resolution of symptoms and signs at the end of the treatment period. Towards the end of the treatment period an indium-labelled white cell scan was performed, which showed normal results. In view of the response to antibiotics a bone biopsy was not performed.



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FIG. 1. A T2-weighted MRI scan of the lateral epicondyle showing a small joint effusion with increased signal in the lateral epicondyle of the humerus and adjacent high signal in the overlying subcutaneous fat.

 
Tennis elbow is usually a clinical diagnosis and does not require any imaging. However, in this case the imaging proved extremely useful in making the diagnosis of osteomyelitis. Plain X-rays in tennis elbow are usually normal. Radioisotope bone scans and infrared thermography in tennis elbow have been studied by Thomas et al. [3]; they often show abnormalities in the epicondylar soft tissue but these do not extend to the distal humerus. MRI scanning in tennis elbow has been reported in only a single study of seven patients, which showed increased signal in the anconeus muscle in all seven patients but no other abnormalities [4]. The history and imaging results in this case clearly point to a diagnosis of osteomyelitis, although osteonecrosis and localized osteoporosis should be included in the differential diagnosis. The lateral epicondyle is not a site usually associated with the last two diagnoses [5, 6] and neither has been reported to occur after soft tissue injection. The rapid response to antibiotics also supports the diagnosis of osteomyelitis.

This case illustrates the need for vigilance even after performing common procedures, and raises two important clinical issues. First, transient exacerbation of symptoms after local steroid injection is an expected complication, but the appearance of new physical signs should alert the physician to review the diagnosis and consider the need for further investigation. Secondly, there are no clear guidelines for primary care physicians (or rheumatologists) regarding the number of steroid injections that can be safely carried out at one site or the optimum time interval between injections. These issues should be addressed in the future.

Notes

Correspondence to: Dr S. Allard. Back

References

  1. Buckley SL, Alexander AH, Barrak RL. Scapular osteomyelitis. An unusual complication following subacromial corticosteroid injection. Orthop Rev1989;18:321–4.[Medline]
  2. Gidumal R, Evanski P. Calcaneal osteomyelitis following steroid injection: a case report. Foot Ankle1985;6:321–6.
  3. Thomas S, Siahamis G, Marion M, Boyle C. Computerised infrared thermography and isotopic bone scanning in tennis elbow. Ann Rheum Dis1992;51:103– 7.[Abstract]
  4. Coel M, Yamada CY, Ko J. MR imaging of patients with lateral epicondylitis of the elbow (tennis elbow): importance of increased signal of the anconeus muscle. Am J Roentgenol1993;161:1019–21.[Abstract]
  5. Lavernia CJ, Sierra RJ, Grieco FR. Osteonecrosis of the femoral head. [Review]. J Am Acad Orthop Surg1999;7:250–61.[Medline]
  6. McCarthy EF. The pathology of transient regional osteoporosis. Iowa Orthop J1998;18:35–42.[Medline]
Accepted 24 January 2000





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