Bilateral diaphyseal bone cysts of the tibia mimicking shin splints in a young professional athlete—a case report and depiction of a less-invasive surgical technique

A 17-year old male professional runner was transferred to our musculoskeletal tumor centre on recommendation from his team doctor. Currently a member of a national biathlon junior team, the patient was one of the best track and field athletes of his age group for mid-distance running disciplines (1500 m & 3000 m) on a competitive level at the time of initial diagnosis. Besides daily workout in the gym for strentgh and endurance, his training schedule included up to 4 h running 6 days per week. However, ongoing pain in both of his shins prevented the young athlete from training and competition despite intensive conservative treatment for 5 months. Before admission to our hospital, symptoms were treated for shin splints without success until MRI was conducted. Extensive cyst-like bone lesiosn were found in both diaphyseal tibiae (Figs. 1 and 2). Imaging was completed by plain radiography of both tibiae (Figs. 3 and 4).

As multimodal conservative treatment for MTSS demonstrated unsuccessful and MRI revealed the most likely reason for the patient’s symptoms, surgical therapy was indicated after thorough analysis of all clinical and radiological findings. In favour of a fast return to a competitive sports level we abandoned our standard surgical procedure for UBC consisting of open curettage and autologous cancellous bone grafting from the iliac crest. Due to the dimensions of both tibial lesions, this would have been associated with a long recovery and potential major donor site morbidity both seriously jeopardizing the young athlete’s competitive sports career. Based on promising reports of minimally invasive surgery for treatment of UBC of the humerus from Hou et al. [7, 8] we performed a customized surgical technique for the first time at the lower extremity beginning with the more symptomatic left lower leg. Surgery was conducted in a supine position without use of a pneumatic tourniquet to prevent possible muscular impairment. The exact dimension of the cyst and its distance from the lateral knee joint line and the tibiotalar joint line were marked on the skin. Intraoperative fluoroscopy was used to confirm correct localization. After a skin incision of two inches (Fig. 5) the soft-tissue layers were dissected bluntly in a longitudinal direction down to the fascia of the anterior tibial muscle. The muscle was stripped from the antero-lateral facet of the tibia with its fascia, leaving a narrow strip of fascia on the edge of the tibia allowing easy later refixation. After detachment of the periost, a small bony fenestration was created by 2 mm K-wire cortical corner drillings and connecting oscillating saw cuts. Sawcuts were placed slightly tangential to hinder the bony lid to fall through the window after curettage and grafting. Before completing all four sides of the bony window further drill holes on each side of the cranial and caudal osteotomy site were placed for additional suture cerclages for later reattaching the lid. Then the content of the cyst was aspirated and sent for cytological analysis, followed by a routinely smear test for microbiological analysis. The membrane lining and any septa within the cyst were disrupted and removed with a long flexible arthroscopic ring curette (Arthrex, Germany). Specimen of the membrane were sent for histoptahologic analysis. Fluoroscopy ensured treatment of the entire cyst. Hou et al. (Taiwan) [8] proposed the use of custom-made curved curettes and impactors. In accordance with current medical laws, we converted several surgical instruments for our needs: A 2.0 mm K-wire was fixed in a universal chuck with T-handle (Synthes, Switzerland) and its sharp end bent 60–90° to use as a scraper. Furthermore a 6.0 mm sponylodesis titan rod was bent and utilized as impactor. After repeated chemical cauterization with 95 % ethanol and intermittent irrigation with normal saline solution, grafting was performed. For grafting, autlogous bone material was not the preferred choice for obviuos reasons. Bone substitutes like calcium sulfate pellets, as suggested by several other authors, have not met our expecetations in the past, can show poor osteointegration in adult patients and can entail adverse effects [9]. Thus allogenic cancellous bone (Tutoplast©, RTI Biologics/Tutogen Medical, Neunkirchen/Germany) was administered and firmly impacted within the cyst space. Finally, the fenestration was closed by reattaching the cleaned bone cover and secured with transosseous sutures. A cannulated 6.5 mm screw was inserted caudally the small fenestration under fluoroscopic guidance to provide continuous decompression.

Histopathologic examination confirmed the diagnosis of UBC. Microbiology results of the smear test showed no signs of bacterial infection. After complete wound healing the patient was allowed to resume modest physical activity with cycling and swimming to regain muscular strength and decrease muscle atrophy. Six months after initial surgery on the left tibia and 3 months after last surgery on the contralateral right side the athlete had regained his full training capacity on a competive level and has been free of symptoms eversince. Clinical and radiographic follow-ups showed desirable bony consoldidation of the tibiae without signs of recurrence (Figs. 6 and 7). Three years after initial surgery, both cannulated screws were removed percutaneously. Proving the therapeutical succes of our less-inavsive procedure and showing a desirable healing process, the athlete qualified for this years Biathlon Junior World Championships in Belarus 8 month after final surgery.