DEFINITION

Enchondromas are benign cartilaginous neoplasms that are commonly seen in the medullary cavity of phalanges and metacarpals and less commonly in 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 neoplasm of bone, which is locally aggressive and can metastasize. Although 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.

 

 

 

 

FIG 1 • A. Enchondroma of the proximal phalanx. B. Unicameral bone cyst of the distal radius. C. Giant cell tumor of the distal radius.

 

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.7

 

Enchondromas can extremely rarely transform to chondrosarcomas.

 

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.

 

 

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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.1,2,4,5,6 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).

 

Magnetic resonance imaging (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).

 

 

 

 

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).

 

 

Campanacci et al's3 grading system or Kang et al's4 modification 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 computed tomography (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

 

Enchondromas and unicameral bone cysts may be observed provided radiographic assessment is diagnostic or the differential diagnoses are 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.

 

The surgeon must secure and confirm the availability of any necessary grafting materials, instruments, implants, or adjuvants (ie, liquid nitrogen).

 

 

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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 arm board. 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.

 

Ulnar 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.

 

TECHNIQUE

• Curettage and Excision of Proximal Phalangeal Enchondroma

  The midaxial 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.

   

  TECH FIG 1 • A. Midaxial approach to proximal phalanx enchondroma. B. The lateral band is retracted and a bone window is created before curettage.

  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.

• 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.

   

  Grades 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.

   

  P.1333

   

  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.

   

   

   

  TECH FIG 2 • A. The right radius is approached from the palmar radial aspect between the first dorsal compartment and the radial artery. SRN, superficial radial nerve; RA, 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.

   

   

  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.

• 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, whereas 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.

 

 

P.1334

 

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.

 

 

 

PEARLS AND PITFALLS
	“Exteriorization” ▪ Make the bone window to the lesion two-thirds the greatest dimension of the lesion to allow adequate visualization of the cavity.     Pathology ▪ Consult the pathologist in advance. Frozen section analysis of cartilaginous consultation lesions is notoriously difficult.     Approach ▪ A lateral approach to phalanx lesions provides more rapid return to normal motion and a better appearance. A volar radial approach for distal radius grade 1 and 2 giant cell tumors of bone allows excellent visualization and limits local contamination risk. The dorsal approach for large grade 3 giant cell tumor distal radius lesions is best when wide excision and reconstruction or arthrodesis is anticipated.     Monitoring ▪ Surveillance monitoring is mandatory, particularly for giant cell tumor of bone,

 

 

 

	which can recur late and metastasize.

 

 

 

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. Active-assisted and passive range-of-motion exercises are added at week 6.

 

 

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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-of-motion 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.7

 

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 or extension limited to a

 

single plane of palmar perforation bound by pronator quadratus (grade 1 and 2 lesions).4,5,6 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.4,5,6,9

 

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%.7

 

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.4,6

 

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.1,2,5 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;22(1):91-98.

    

    

2. Averill RA, Smith RJ, Campbell CJ. Giant-cell tumors of the bones of the hand. J Hand Surg Am 1980;5(1):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. Kang L, Manoso MW, Boland PJ, et al. Features of grade 3 giant cell tumors of the distal radius associated with successful intralesional treatment. J Hand Surg Am 2010;35(11):1850-1857.

    

    

5. 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;76(12):1827-1833.

    

    

6. Sheth DS, Healey JH, Sobel M, et al. Giant cell tumor of the distal radius. J Hand Surg Am 1995;20(3):432-440.

    

    

7. Takigawa K. Chondroma of the bones of the hand. A review of 110 cases. J Bone Joint Surg Am 1971;53(8):1591-1600.

    

    

8. Vander Griend RA, Funderburk CH. The treatment of giant-cell tumors of the distal part of the radius. J Bone Joint Surg Am 1993;75(6):899-908.

    

    

9. Weiland AJ, Kleinert HE, Kutz JE, et al. Free vascularized bone grafts in surgery of the upper extremity. J Hand Surg Am 1979;4(2): 129-144.