Case Reports 

Unicameral Bone Cyst of the Humeral Head: Arthroscopic Curettage and Bone Grafting

Pietro Randelli, MD; Paolo Arrigoni, MD; Paolo Cabitza, MD; Matteo Denti, MD

  • Orthopedics
  • January 2009 - Volume 32 · Issue 1

No abstract available for this article.

Abstract

Arthroscopic surgery has improved greatly over the past decade. Treatment of various juxta-articular disorders around the shoulder have benefited from endoscopic approaches. Cystic lesions of the shoulder on the scapular side have been treated in this way. This article describes a case of a 29-year-old patient with a unicameral bone cyst on the posterior aspect of the humeral head. Arthroscopic visualization using an accessory posteroinferior portal localized the cyst through the bare area of the humeral head. A cannulated burr was used to create an opening through the cortical wall between the cyst and the joint, and a careful curettage was performed. The cavity was filled with a demineralized bone matrix enriched with autologous blood packed into an arthroscopic cannula and delivered through the accessory portal. The patient reported pain relief immediately postoperatively and at follow-up. This case demonstrates the feasibility of arthroscopic treatment of a simple bone cyst of the humeral head. We believe that the knowledge of the juxta-articular anatomy allows the applications of scope-assisted procedures to be expanded, maximizing the results of a technique that allows a shorter recovery and less painful rehabilitation.

Arthroscopic surgery has improved greatly over the last decade. Treatment of various juxta-articular disorders around the shoulder have benefited from endoscopic approaches. Cystic lesions of the shoulder on the scapular side have been treated in this way.1,2

This article presents a case of a young, active man in whom arthroscopy was used in the treatment of a unicameral bone cyst at the posterior aspect of the humeral head, with local application of demineralized bone matrix.

Case Report

A 29-year-old man presented with chronic pain in his right shoulder. He reported a history of acute pain radiating to the posterior aspect of his shoulder 10 years previously while working out at a bench press. Plain radiographs at that time revealed a small unicameral bone cyst at the posterior aspect of the humeral head with a limited fracture on its lateral surface. The patient was treated conservatively and followed up routinely with standard radiographs. He reported no further traumatic events. After a pain-free period, the patient experienced pain associated with heavy overhead activities. During this period the cyst had not developed an aggressive appearance.

At initial evaluation on presentation, the patient had full range of movement and normal strength. Plain radiographs (anteroposterior, lateral, axillary, and outlet projections) and magnetic resonance imaging (MRI) showed a cystic area at the posteroinferior aspect of the humeral head (compressing a thin cortical layer), consistent with the previous finding. Computed tomography (CT) scanning and a technetium-99 bone scan were also performed (Figure 1). The imaging studies, history, and clinical examination supported the diagnosis of a unicameral bone cyst limited by a compressed posterior cortex. Surgical curettage and grafting were recommended. The position of the cyst, relatively close to the intra-articular bare area of the humerus, encouraged us to attempt the procedure using an arthroscopic approach, with a plan to proceed to open surgery if necessary.

Figure 1: The cyst located at the posterolateral aspect of the humeral head Figure 2: Arthroscopic view of the preparation of the bone cyst Figure 3: Postoperative AP radiograph of the humeral head

Figure 1: Preoperative CT scan showing the cyst, measuring approximately 2×2 cm, located at the posterolateral aspect of the humeral head. Figure 2: Arthroscopic view of the preparation of the bone cyst. Preparation of the moldable allograft packed into the cannula (inset). Figure 3: Postoperative AP radiograph of the humeral head, 2 years after introduction of the graft.

Shoulder arthroscopy was performed in the lateral decubitus position under a scalene block with sedation. Diagnostic glenohumeral arthroscopy was performed using a 30° arthroscope through a standard posterior portal and an arthroscopic pump maintaining a pressure of 50 mm Hg. A standard anterior portal was introduced using an outside–in technique.

Based on the MRI and CT scans, a K-wire was drilled parallel to the glenoid plane, 4 cm distal to the posterolateral corner of the acromion. Under intra-articular vision, the K-wire was placed between the articular margin and the posterior rotator cuff. A decrease in resistance during the insertion of the K-wire confirmed the correct location within the cyst. An accessory posteroinferior portal was created to reach the cyst. A 7.0-mm cannulated burr was used to create an opening through the cortical wall between the cyst and the joint, which led to an abundant flow of bloody fluid from the cavity. By rotating the arm externally, excellent visualization of cyst cavity was possible via the posterosuperior viewing portal. Arthroscopic inspection of the inner part of the cyst revealed a soft, red membranous tissue, as well as some organization of coagulated material within the cyst. Thorough curettage and debridement of the cyst was performed and all membranous material removed (Figure 2). Histological examination of the membrane confirmed the diagnosis of a unicameral bone cyst.

Allogenic bone chips with demineralized bone matrix (Osteofil ICM moldable blocks; RTI Biologics, Inc, Alachua, Florida) were mixed with the patient’s autologous blood (30 ml). This preparation was packed into a 5.75-mm crystal cannula (Arthrex, Inc, Naples, Florida; Figure 2).

The cannula was inserted into the cyst via the accessory posteroinferior portal and the graft material progressively packed into the cavity. The bone graft was packed continuously until it reached the same level as the native bare area of the humerus, and radiographs confirmed the correct position of the graft.

The patient was discharged the day after arthroscopic surgery and reported immediate pain relief. At 6-, 12- and 24-month follow-up, he continued to report excellent pain relief and had normal shoulder function. The most recent radiographs demonstrated good graft osteointegration (Figure 3).

Discussion

Simple or unicameral bone cysts are common, benign, fluid-filled lesions usually located in the long bones of children before skeletal maturity.3-5 Although these defects are not malignant, they may create major structural alterations of the long bones, in particular at humeral and femoral metaphysis. They are commonly discovered when radiographs are taken for other reasons or on the occasion of a pathological fracture.2 Various treatments have been suggested, but the only reliable predictor of success of any treatment strategy is the age of the patient: the younger the patient, the higher the risk of recurrence.3,4

The dual goal of management is to enable the formation of bone or provide a substitute that can withstand the stresses of use by the patient and to interrupt bone destruction demonstrated by serial radiographic follow-up.4 Open surgery is rarely justified for the initial treatment of a unicameral bone cyst, but there is some debate concerning the relative effectiveness of closed methods.3 In a recent study comparing the results of steroid injection with those of autologous bone marrow grafting for the treatment of unicameral bone cysts in 60 patients, the overall success rates were 86.7% and 92.0%, respectively (P>.05).3 However, small but significant differences exist in favor of surgical intervention in terms of recurrence and number of procedures required. We believe that, especially in skeletally mature patients, the treatment that potentially could give the highest chances of a definitive solution should be recommended.

Given the benign nature of a unicameral bone cyst, the gold standard management continues to be open curettage with bone grafting.3-5 The harvest of autologous bone, usually from the iliac crest, has the drawback of necessitating a second surgery at the donor site. Recent research has improved different grafting techniques, including bioactive materials6 and demineralized bone matrix in combination with iliac crest injections.7 Our technique is based on the use of demineralized bone matrix combined with autologous blood, which does not require bone or bone marrow harvesting, is easily reproducible, and is associated with a low morbidity.

The arthroscopic procedure described has several benefits and some drawbacks: the incision is small, blood loss is minimal, and rehabilitation can be started sooner than after open surgery because tissue damage is minimal.1,2,7 A full arthroscopic evaluation of any intra-articular pathologies is possible. However, the technique is demanding and an eventual conversion to open surgery during the learning curve could be complicated by fluid extravasation and soft tissue swelling. A pilot study on a systematic series of patients would clarify the indications for this approach.

This case demonstrates the feasibility of arthroscopic treatment of a simple bone cyst of the humeral head. We believe that the knowledge of the juxta-articular anatomy allows the applications of scope-assisted procedures to be expanded, maximizing the results of a technique that allows a shorter recovery and less painful rehabilitation.

References

  1. Lee SB, Harryman DT II. Local arthroscopic bone grafting of a juxta-articular glenoid bone cyst. Arthroscopy. 1997; 13(4):502-506.
  2. Murata K, Nakagawa Y, Suzuki T, Kobayashi M, Kotani S, Nakamura T. Intraosseous ganglion about to cause a fracture of the glenoid: a case report. Knee Surg Sports Traumatol Arthrosc. 2007; 15(10):1261-1263.
  3. Cho HS, Oh JH, Kim HS, Kang HG, Lee SH. Unicameral bone cysts: a comparison of injection of steroid and grafting with autologous bone marrow. J Bone Joint Surg Br. 2007; 89(2):222-226.
  4. Baig R, Eady JL. Unicameral (simple) bone cysts. South Med J. 2006; 99(9):966-976.
  5. Kanellopoulos AD, Mavrogenis AF, Papagelopoulos PJ, Soucacos PN. Elastic intramedullary nailing and DBM-bone marrow injection for the treatment of simple bone cysts. World J Surg Oncol. 2007; (5):111.
  6. Sponer P, Urban K. Treatment of juvenile bone cysts by curettage and filling of the cavity with BAS-0 bioactive glass-ceramic material [in Czech]. Acta Chir Orthop Traumatol Cech. 2004; 71(4):214-219.
  7. Oh JH, Kim HH, Gong HS, Lee SL, Kim JY, Kim WS. Primary aneurysmal bone cyst of the patella: a case report. J Orthop Surg (Hong Kong). 2007; 15(2):234-237.

Authors

Drs Randelli, Arrigoni, and Cabitza are from the University of Milan, and Dr Denti is from Galeazzi Orthopaedic Institute, Milan, Italy.

Drs Randelli, Arrigoni, Cabitza, and Denti have no relevant financial relationships to disclose.

Correspondence should be addressed to: Pietro Randelli, MD, Università degli Studi di Milano, IRCCS Policlinico di Scienze Medico-Chirurgiche Via Morandi 30, 20097, San Donato Milanese, Milan, Italy.

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