Chondroblastoma is a rare intermediate grade cartilaginous neoplasm, representing less than 1% of all primary bone tumors1. It typically arises in the epiphysis or apophysis of long bones in young patients, predominantly males1, but it is unusual to observe this type of tumor in the acromion2. Surgery with curettage and bone grafting is the mainstay of treatment. Chemical (phenol) and electric cauterization or cryosurgery can be used as complementary therapy2-5. The rate of recurrence after these procedures has been reported to be between 10% and 35%4,5.
Herein, we discuss clinical presentation, workup, and treatment of a patient with a recurrent chondroblastoma of the acromion.
The patient was informed that data concerning the case would be submitted for publication, and he provided consent.
A 38-year-old man presented to our division with pain in his right shoulder girdle with onset occurring approximately one and a half years earlier.
Physical examination revealed shoulder asymmetry with a palpable tumor mass in the acromial region. Palpation of the acromion was painful. Also, active range of motion (ROM) was moderate restricted due to pain. He presented active forward elevation of 150° and abduction of 160°, active external rotation of 50° with the arm at the side, and active internal rotation with the thumb reaching the spinous process L2. Because of pain and loss of strength, the patient was severely restricted during activities of daily living, was unable to work as a mechanic, and was unable to perform overhead activities.
Computer tomography (CT) showed an expansile osteolytic mass in the right acromion with intralesional calcifications (Figs. 1-A and 1-B). Magnetic resonance imaging (MRI) confirmed the presence of a lobulated tumor with a signal appearance typical of cartilage lesions (Figs. 1-C, 1-D and 1-E). In addition to the typical radiomorphological appearance of a chondrogenic tumor, the surrounding edema was suggestive of chondroblastoma.
Histology by biopsy (Fig. 1-F) confirmed diagnosis of chondroblastoma, and the patient underwent intralesional curettage and allogeneic bone grafting.
During regular follow-up visits, a local tumor recurrence was observed approximately 11 months after the first operation. At that time, he presented an active forward elevation of 150° and abduction of 140°, external rotation of 50° with the arm at the side, and active internal rotation with the thumb reaching the third lumbar vertebra. MRI presented tumoral lesions at the origin of the deltoid muscle and adjacent to the acromioclavicular joint (Figs. 2-A and 2-B), which was not accessible for a further curettage because of the large size of the lesion and the small residual acromion. Computed tomography of the thorax showed no evidence of metastases.
To preserve a functionally intact shoulder girdle, anatomical reconstruction of the acromion was performed as follows. Surgery took place in the left lateral position on a flat top table. A utilitarian s-shaped approach from the deltopectoral groove to the spine of the scapula with excision of the former incision exposed the acromion. After resection of the coracoacromial ligament at the coracoid process, the deltoid muscle was detached from the acromion. The osteotomy of the clavicle was performed 1 cm medial to the acromioclavicular joint, and the acromion was separated dorsally at the transition to spine of the scapula (Fig. 2-C). A tricortical, trapezoid-shaped graft was harvested from the middle portion of the iliac bone. Size and shape were estimated based on preoperative 3-dimensional CT analysis of the healthy contralateral side. It was prepared to a bicortical graft with cancellous bone edges to promote bone fusion on the one hand and reinsertion of the deltoid muscle on the other. The inner surface constituted the new undersurface of the acromion, and the thin central part was used for transosseous deltoid reinsertion. Two t-shaped angular stable plates (3.5 mm T-LCP; DePuy Synthes) were used to fix the graft at the spine of the scapula and the clavicle. The deltoid muscle was reattached with FiberWire sutures (Arthrex) through drilled holes at the anterior, lateral, and posterior borders of the graft and sutures directly to the plates neutralized tension forces (Figs. 2-D through 2-F). Additional polydioxane sutures (Ethicon) were used for soft-tissue adjustment and closure of the deltopectoral groove.
An inflatable shoulder abduction cushion (medi SAK; medi) was applied directly in the operating room with shoulder flexed and abducted in 60°. Passive motion from 60° to 120° was allowed for 3 months. Thereafter, a 15° shoulder abduction splint (medi SAS 15; medi) was applied for another 6 weeks. Free passive motion and active-assisted exercises were allowed with transition to active exercises after 3 weeks.
The patient exhibited steady improvement of active ROM, and at the latest follow-up (17 months after surgery), he had forward flexion to 155° and abduction to 160°. External rotation was 50°, and internal rotation was to spinous process L3 (left shoulder: forward flexion 170°, abduction 170°, external rotation 60°, and internal rotation L1) (Figs. 3-A through 3-C). The Constant score6 was 77, demonstrating a good functional outcome. The evolution of the integration process was documented through follow-up visits with repeated MRI and CT scans and x-rays every 3 to 4 months, resulting in radiologically healed graft after 7 months. There was no evidence of local recurrence at the latest follow-up of 17 months.
Chondroblastoma is a rare, cartilage-producing bone tumor7,8. It is characterized histologically by the proliferation of immature chondrocytes (chondroblasts) along with other secondary elements, such as mature cartilage, giant cells, calcification, and occasionally, aneurysmal bone cyst formation7,9. Most tumors are diagnosed in the second and third decades of life with a male predominance (2 to 1)7,10,11.
Chondroblastoma tends to be a solitary lesion7. However, recently, a metachronous bilateral chondroblastoma of the proximal part of the femur was described12. In young people, it preferentially occurs in the epiphysis of long tubular bones, with the most common sites being the proximal tibia or femur, distal femur, and proximal humerus13. In older individuals, the location is more variable, and tumors may involve nontubular bones such as the craniofacial skeleton or bones of the hands and feet11,14. It is highly exceptional for the acromion to be involved2, as in our case. It very rarely metastasizes—a benign metastasizing chondroblastoma—but does not transform into a high-grade tumor15.
Clinical presentation typically consists of gradually increasing pain and local tenderness, followed by swelling and reduced range of motion of the adjacent joint3. In our case, pain was the major complaint, he had a palpable mass on the acromion, and ROM was restricted.
Surgery is the treatment of choice. The accepted method is curettage and filling of the bone defect with a bone graft, which generally results in satisfactory outcomes2. Another treatment option represents the en bloc resection. Chemical (phenol) and electric cauterization or cryosurgery can be used as complementary therapy. However, local tumor recurrence rate is relatively high, on the order of 14% to 18%, depending somewhat on the initial location7,11,14.
The initial operation consisted of curettage and bone grafting. Unfortunately, the chondroblastoma recurred, requiring a revision surgery.
In general, after resection of the acromion, the reattachment of the deltoid muscle is crucial to preserve a functional shoulder joint. Using an autologous iliac crest graft, we achieved an anatomical reconstruction of the acromion with transosseous reinsertion of the deltoid muscle, and the patient regained normal shoulder function without relevant deficits during activities of daily living. There was no evidence of recurrence at a follow-up of 17 months. Furthermore, radiographs demonstrated complete bony fusion of the iliac graft (Figs. 3-D through 3-F).
To the best of our knowledge, this is the first description of a functional and anatomical reconstruction of the acromion using an autologous iliac crest craft fixed with t-shaped angular stable plates. This surgical procedure is very beneficial for advanced tumors requiring resection of the acromion to restore and preserve a functionally intact shoulder girdle, particularly in young and functionally demanding patients. In contrast, conventional alternative methods such as acromial resection or shoulder arthrodesis are functionally debilitating and should be avoided whenever possible.
In conclusion, the initial tumor in the acromion was large, and achieving adequate curettage was likely difficult, making local recurrence not unanticipated. Resection followed by autologous iliac bone graft fixation demonstrated a good clinical outcome, without evidence of local recurrence as of the time of this writing 17 months after secondary surgery.
Therefore, this surgical procedure could be considered for large, expansile lesions in this location for which adequate curettage would leave little remaining bone that might compromise function.
Note: The authors would like to thank Dr. Christian Pasluosta (Freiburg) for his valuable assistance on English language editing as well as Stephan Köhler (Freiburg) for preparation of the illustrations.
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