Edward A. Athanasian
DEFINITION
Enchondromas are benign cartilaginous neoplasms that are commonly seen in the medullary cavity of phalanges and metacarpals and less commonly the radius and ulna. Enchondroma is the most common neoplasm of bone arising in the hand.
Unicameral bone cysts are benign endothelial-lined fluid-filled cavities arising in metaphyseal bone; they are occasionally seen in the distal radius and rarely seen in the hand.
Giant cell tumor of bone is an uncommon benign neoplasm of bone, which is locally aggressive and can metastasize. While its histology suggests a benign process, is behaves as a lowgrade malignancy.
ANATOMY
Enchondroma most commonly arises in the proximal phalanx or metacarpal when seen in the hand (FIG 1A). It can be seen in metaphyseal and epiphyseal regions and is typically confined to the bone. The enchondroma may distend the bone and pathologic fracture may be seen.
Unicameral bone cysts are rarely seen in the hand. When presenting in the radius they are often metaphyseal and may be in continuity with the distal radial physis (FIG 1B). Unicameral bone cysts are typically confined to bone and pathologic fracture may be seen.
Giant cell tumor of bone most commonly arises in the epiphyseal region except in the skeletally immature patient, in whom it may arise in the metaphysis. The distal radius is the third most frequent location for these tumors (FIG 1C), after the distal femur and the proximal tibia. Hand lesions account for 2% of giant cell tumors of bone.
PATHOGENESIS
The pathogenesis of enchondroma, unicameral bone cyst, and giant cell tumor of bone is uncertain. Enchondroma and unicameral bone cysts may be associated with bone development and growth.
Enchondroma, unicameral bone cyst, and giant cell tumor of bone can weaken the bone and predispose the patient to pathologic fracture.
NATURAL HISTORY
Enchondromas are most commonly identified incidentally during unrelated evaluation. They also can present after pathologic fracture. On occasion, a patient may complain of painful swelling in the bone.
Enchondromas found incidentally and not causing considerable mechanical weakness may be observed if typical radiographic findings are seen.
Enchondromas causing substantial fracture risk and those presenting after pathologic fracture can be treated surgically with a low risk of recurrence.6
Enchondroma can extremely rarely transform to chondrosarcoma.
Unicameral bone cysts are most commonly seen during adolescence or childhood. They are most commonly identified after pathologic fracture. Proximal humerus lesions may be seen.
Unicameral bone cysts with a low risk of fracture may be observed with activity modification.
Unicameral bone cysts causing substantial weakness and fracture risk may be treated with surgery or injection.
Suspected unicameral bone cysts in the bones of the hand are sufficiently rare that strong consideration should be given to biopsy when this lesion is suspected.
FIG 1 • A. Enchondroma of the proximal phalanx. B. Unicameral bone cyst of the distal radius. C. Giant cell tumor of the distal radius.
Giant cell tumor of bone is locally aggressive. Patients may present with pain and swelling or after pathologic fracture.
Giant cell tumor of bone metastasizes 2% to 10% of the time, with metastasis more frequently seen with distal radius and hand lesions.1,2,4,5 Metastasis most frequently occurs concurrent with or after a local recurrence.
Patients with giant cell tumor of bone require systemic staging, treatment, and long-term surveillance, as recurrence may be seen late.
PATIENT HISTORY AND PHYSICAL FINDINGS
Enchondroma is most often an incidental finding and is asymptomatic. Pain and deformity can be seen after pathologic fracture. On occasion there will be bone distention and tenderness with palpation.
Unicameral bone cysts are most commonly seen after pathologic fracture. On occasion there will be swelling and tenderness.
Giant cell tumor of bone may cause swelling, pain, tenderness, and a sense of weakness. Loss of range of motion is common as these lesions are typically periarticular. Pathologic fracture may be seen.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs are indispensable in the initial evaluation of primary bone tumors (FIG 2A).
MRI is useful when an aggressive lesion or soft tissue extension is suspected. MRI may allow better identification of the local extent of disease and may assist in operative planning (FIG 2B).
Campanacci et al's3 grading system may be used:
Grade 1 lesions are confined to the intramedullary cavity without distention or distortion of the cortex.
Grade 2 lesions distend the cortex but do not extend into the surrounding soft tissues.
Grade 3 lesions destroy the cortex and extend into the surrounding soft tissues.
Total body bone scan and lung CT scan are required for staging patients with giant cell tumor of bone.
Incision or needle biopsy may be required when radiographs and MRI are not diagnostic.
DIFFERENTIAL DIAGNOSIS
Enchondroma
Chondromyxoid fibroma
Chondrosarcoma
Unicameral bone cyst
Infection
Aneurysmal bone cyst
Giant cell tumor of bone
Primary malignant bone neoplasms
Acrometastasis
NONOPERATIVE MANAGEMENT
Enchondroma and unicameral bone cyst may be observed provided radiographic assessment is diagnostic or the differential is limited to benign, nonaggressive lesions with an indolent natural history. The assessment of risk of pathologic fracture is paramount. Lesions with a substantial risk of pathologic fracture in the context of the patient's activity level are best treated operatively.
The rare risk of malignant degeneration of enchondromas should be considered and discussed with the patient.
Suspected giant cell tumor of bone requires biopsy. Rarely these can be treated with radiation alone; however, this approach is the exception and should not be considered first-line treatment. Radiation is associated with a risk of subsequent true malignant degeneration to a highly malignant giant cell tumor of bone.
SURGICAL MANAGEMENT
All suspected giant cell tumors of bone and those enchondromas and unicameral bone cysts with a high risk of fracture are best treated surgically.
Preoperative Planning
The radiographic extent of disease must be assessed.
The approach will vary depending on the anatomic location.
Bone graft source (autologous or allograft) must be considered.
Precautions to prevent donor-site cross-contamination must be considered and reviewed with the operating room team.
The surgeon must determine the anticipated need for frozen section and discuss this with the pathologist and review radiographs before any anticipated frozen section.
FIG 2 • A. Radiograph showing giant cell tumor of the metacarpal. B. MRI axial image of grade 3 giant cell tumor of the distal radius (arrow).
The surgeon must secure and confirm the availability of any necessary grafting materials, instruments, implants, or adjuvants (ie, liquid nitrogen).
The surgeon must confirm the availability of intraoperative imaging. Radiographs will give better resolution than fluoroscopy.
Positioning
Surgery is typically done in the supine position with the arm extended on a radiolucent armboard.
Proximal humerus lesions may be approached in a modified beach-chair position.
Approach
Phalanx lesions may be approached from the dorsal or lateral approach.
Metacarpal lesions are best approached dorsally in most instances.
Carpal lesions are usually best approached dorsally.
Distal radius lesions may be approached at the tubercle of Lister or at the interval between the radial border of the pronator quadratus and the first dorsal compartment, proximal to the radial styloid.
Ulna lesions are usually best approached dorsally or ulnarly.
Proximal humerus lesions are best approached just lateral to the deltopectoral interval.
Biopsy must always take into consideration the potential for malignancy. It must be done in a way that does not compromise the potential need for a subsequent limb-sparing procedure.
TECHNIQUES
CURETTAGE AND EXCISION OF PROXIMAL PHALANGEAL ENCHONDROMA
The mid-axial approach from the ulnar side is preferred whenever possible (TECH FIG 1A).
After making the incision under tourniquet control, identify the lateral band and retract it dorsally.
Reflect the periosteum and create a bone window using curettes, rongeur, or drill (TECH FIG 1B).
Curette the lesion in its entirety. The use of flexible fiberoptic lights may improve visualization.
Pack the cavity with preferred bone grafting material.
Obtain plain radiographs in the operating room to confirm complete excision and appropriate grafting.
TECH FIG 1 • A. Mid-axial approach to proximal phalanx enchondroma. B. The lateral band is retracted and a bone window is created before curettage.
CURETTAGE AND EXCISION OF METACARPAL ENCHONDROMA
Metacarpal lesions are approached dorsally through longitudinal incisions.
Reflect the periosteum and create a bone window using curettes, rongeur, or drill.
Curette the lesion in its entirety. Ensure adequate visualization through a longitudinal bone trough.
Pack the cavity with preferred bone grafting material.
Obtain plain radiographs in the operating room to confirm complete excision and appropriate grafting.
CURETTAGE, CRYOSURGERY, AND CEMENTATION OF DISTAL RADIUS GIANT CELL TUMOR OF BONE
Preoperative preparation includes confirming the availability of liquid nitrogen, proper storage containers, cryosurgery instruments, and trained operative staff.
Grade 1, 2, or 3 lesions with a single plane of palmar perforation can be approached from a palmar radial incision between the first dorsal compartment and the radial artery (TECH FIG 2A,B).
A branch of the superficial radial nerve may be encountered and should be retracted and protected. The radial 50% of the pronator quadratus is exposed.
When palmar soft tissue perforation is present it will commonly be contained by the pronator quadratus. The pronator overlying the region of perforation should be excised en bloc with the bone window, effectively converting a grade 3 lesion to a grade 2 lesion with a palmar bone window.
Wide exteriorization of the lesion with a window roughly two-thirds the maximum dimension of the lesion is needed to ensure adequate visualization.
Thoroughly curette the lesion. Fiberoptic lighting may assist in viewing the extent of radial styloid involvement.
Burr the endosteal surface if it is sufficiently thick. Irrigate and dry the cavity.
The argon beam coagulator may be used to achieve hemostasis in the cavity and may have a beneficial effect as an adjuvant causing surface necrosis.
Perform cryosurgery using three separate freeze–thaw cycles with either the direct pour technique or the spray gun (TECH FIG 2C).
Fill the cavity with polymethylmethacrylate bone cement. Reinforcing Rush pins (Rush Pin, Meridian, MS) may be used (TECH FIG 2D).
Apply a bulky compressive bandage and volar splint.
TECH FIG 2 • A. The right radius is approached from the palmar radial aspect between the first dorsal compartment and the radial artery. B. The radial border of the pronator quadratus is exposed to gain access to the lesion for creation of the bone window. C. Cryosurgery is performed after wide retraction and soft tissue protection. D. The defect is filled with bone cement.
WIDE EN BLOC EXTRA-ARTICULAR DISTAL RADIUS RESECTION
Wide extra-articular excision of the distal radius may be indicated for grade 3 giant cell tumors with extensive cortical destruction, recurrent lesions, and those with pathologic fracture into the radiocarpal articulation.
A dorsal approach maximizes exposure and facilitates subsequent intercalary arthrodesis.
Finger extensors are released from the retinaculum while wrist extensors and often thumb extensors or abductors may need to be sacrificed.
Cut the radius proximal to the tumor. Cut the ulna proximal to the distal radioulnar joint, away from the ulnar extent of the lesion (TECH FIG 3A).
“Evert” the radius and ulna into the wound while the interosseous membrane is transected (TECH FIG 3B). Dissect the flexor pollicis longus and the radial artery away from the tumor-bearing segment.
Mobilize the flexor tendons, median nerve, and ulnar nerve away from the tumor-bearing segment.
The midcarpal articulation can be disarticulated initially from a dorsal approach and then circumferentially to complete the resection (TECH FIG 3C).
Alternatively, the midcarpal articulation can be excised en bloc with the tumor-bearing segment by cutting with an oscillating saw from dorsal to palmar through the distal aspect of the distal carpal row bones.
Reconstruction is readily accomplished by means of a vascularized or nonvascularized fibula graft (TECH FIG 3D).
Spanning rigid internal fixation with a 3.5-mm dynamic compression plate lowers the risk of nonunion.
TECH FIG 3 • A. Dorsal exposure of the distal radius and ulna with transection of the radius and ulna proximally. B. The radius and ulna are everted into the dorsal wound to allow palmar exposure and dissection of palmar soft tissues. C. The resection specimen, demonstrating the midcarpal articulation of the proximal carpal row. D. Reconstruction is by means of an osteoseptocutaneous vascularized fibula graft for intercalary arthrodesis. A spanning 3.5-mm compression plate is used for fixation.
POSTOPERATIVE CARE
Phalanx or metacarpal enchondroma
Bulky protective dressings are applied and range of motion is initiated at the first dressing change, usually 8 to 10 days postoperatively.
Protective splinting is continued for 6 weeks after surgery. High-risk activities are restricted for 12 to 16 weeks.
Periodic surveillance continues for 3 to 5 years.
Curettage, cryosurgery, and cementation of distal radius giant cell tumor of bone
Dressings are changed 10 days postoperatively. Sutures are removed and the patient is fitted with a removable splint.
Active range-of-motion exercises are initiated. Activeassisted and passive range-of-motion exercises are added at week 6.
Activities are gradually increased, with high-risk activities being restricted for up to 2 years due to cryonecrosis of bone caused by cryosurgery.
Wide en bloc extra-articular distal radius resection
Patients are dressed in a bulky compressive dressing, most commonly with a volar splint.
Elevation is encouraged for the first 48 hours and digit range of motion is encouraged.
Formal supervised therapy is initiated at the first dressing change, typically 8 to 10 days after surgery.
At that time bandages are removed and sutures can be removed.
Most commonly, active and active-assisted range-ofmotion exercises are initiated. When not exercising, patients are asked to use a protective splint for an additional month. Activities are progressively increased as soft tissue and bone healing allows.
Range-of-motion exercises are initiated no later than 10 days after surgery.
Protective splinting continues a total of 6 weeks minimum after intralesional procedures and until bone healing is confirmed after arthrodesis.
Sporting activities are typically restricted for 12 to 18 weeks. High-risk activities are avoided for longer periods.
Surveillance for local recurrence should continue for 5 years for benign lesions and 10 years for giant cell tumor of bone.
OUTCOMES
Local recurrence
The local recurrence rate after curettage and bone grafting of enchondromas is about 5%. When recurrence is seen, the question of malignant transformation should be considered.6
The local recurrence rate after curettage and bone grafting of giant cell tumor of bone in the distal radius is about 50%, and adjuvants such as liquid nitrogen can lower this to about 20%. Intralesional treatment (curettage) is best reserved for lesions without soft tissue extension (grade 1 and 2 lesions).4,5
Wide excision of distal radius lesions is associated with local recurrence rates of less than 10%; however, reconstruction in the form of articular allograft or intercalary arthrodesis results in inferior function, motion, and strength and higher levels of pain.4,5,8
The local recurrence rate after curettage and bone grafting of giant cell tumor of bones of the hand is about 80%. Isolated curettage without the use of adjuvants cannot be advocated in this setting. There are several successful examples of curettage cryosurgery and cementation of giant cell tumor of the small bones of the hand. This type of procedure is best done at a tumor referral center.1,2
Wide excision or amputation has been advocated for giant cell tumor of bone when it arises in the phalanges or metacarpals. Local recurrence may still be seen, but the rate is probably less than 10%.1,2
The local recurrence rate after curettage of enchondromas arising in the hand is about 5%.6
The local recurrence rate after wide excision or amputation for giant cell tumor of the bones of the hand is less than 10%.
The local recurrence rate after curettage, cryosurgery, and cementation of distal radius giant cell tumor of bone is about 20% to 25% and correlates with soft tissue extension.5
The local recurrence rate after wide excision of distal radius giant cell tumor of bone is likely less than 10%.8
Metastasis
Benign giant cell tumor of bone metastasizes in 2% to 8% in general case series.1,2,4
Motion and strength
Range of digit motion is typically excellent after curettage for enchondroma.
Range of motion of the wrist may be slightly diminished after curettage of enchondromas in the distal radius.
Grip strength is reduced to 60% of normal after wide excision of the distal radius for giant cell tumor with intercalary segmental arthrodesis. Forearm rotation is typically preserved.
COMPLICATIONS
Infection, hematoma, nerve injury, intraoperative fracture, postoperative fracture, nonunion, limited range of motion, and tendon gliding problems may be seen after treatment of enchondroma or giant cell tumor of bone when arising in the upper extremity.
Delayed complications include extensor tendon rupture due to prominent residual ulna, nonunion, and fracture after hardware removal.
REFERENCES
1. Athanasian EA, Wold LE, Amadio PC. Giant cell tumors of the bones of the hand. J Hand Surg Am 1997;22A:91–98.
2. Averill RA, Smith RJ, Campbell CJ. Giant-cell tumors of the bones of the hand. J Hand Surg Am 1980;5A:39–50.
3. Campanacci M, Laus M, Boriani S. Resection of the distal end of the radius. Ital J Orthop Traumatol 1979;5:145–152.
4. O'Donnell RJ, Springfield DS, Motwani HK, et al. Recurrence of giant-cell tumors of the long bones after curettage and packing with cement. J Bone Joint Surg Am 1994;76A:1827–1833.
5. Sheth DS, Healey JH, Sobel M, et al. Giant cell tumor of the distal radius. J Hand Surg Am 1995;20A:432–440.
6. Takigawa K. Chondroma of the bones of the hand: a review of 110 cases. J Bone Joint Surg Am 1971;53A:1591–1600.
7. Vander Griend RA, Funderburk CH. The treatment of giant-cell tumors of the distal part of the radius. J Bone Joint Surg Am 1993; 75A:899–908.
8. Weiland AJ, Kleinert HE, Kutz JE, et al. Free vascularized bone grafts in surgery of the upper extremity. J Hand Surg Am 1979;4A:129–144.