Diagnostic Imaging

A variety of diagnostic imaging techniques permit analysis and localization of the size and extent of the lesion and its impingement on normal anatomy. Although imaging does not typically offer a specific diagnosis, it provides important clues in the evaluation, analysis, and workup of a specific patient.

Plain Radiographs

Plain radiographs afford the best possible resolution and detail of bone and adjacent soft tissues. The anatomic region in question should be fully visualized on all radiographs, and this is achieved by taking an adequate number of views. Plain radiographs are initially performed to assess the presence and location of bone involvement. They may also be the most specific radiologic test for bone tumors.

Computed Tomography

Although conventional radiographs offer considerable spatial information, the higher resolution of CT produces images that are specifically useful in localizing small tumors within a bone and in identifying soft tissue extension or calcification within such growths. Because of its ability to discriminate varying densities, CT allows visual separation between the medullary canal, cortex, and surrounding soft tissues and thus often provides critical information concerning anatomic location (T) for tumor staging. Plain chest radiographs are always obtained before performing a biopsy on a suspected malignancy; chest CT scans are useful for staging histologically defined malignant tumors but are not routinely used for prebiopsy screening studies.

Scintigraphy

Radionuclide “bone scan” imaging can be very helpful in detecting primary and metastatic tumors. However, the phenomenon of increased radiopharmaceutical pooling (increased uptake) in a particular bone or soft tissue area is not at all specific or diagnostic. The technique has two time-variable phases. Within minutes after injection, conditions associated with increased vascularity show abnormally high uptake (i.e., trauma, infection, and neoplasia). Later, the isotopes are actively concentrated; in the skeleton, pooling occurs in woven (new) bone, so any process that forms immature bone would be associated with increased uptake on films taken 2 or 3 h after injection. Radioisotope scans are probably the most helpful to demonstrate lesions that may not have been suspected clinically or in anatomic sites not seen on initial images that focused only on the symptomatic region. These findings can be important in patient management, and they have the potential to alter biopsy or therapeutic plans significantly.

Magnetic Resonance Imaging

MRI is a technique that depends on sophisticated computers to produce excellent delineation of soft tissue contrast, as well as images in the axial, coronal, and sagittal planes. For MRI studies, electromagnets generate strong fields that cause cellular nuclei to “wobble” or “vibrate” at specific frequencies. A number of technical factors affect the MRI signal, including echo time (TE), pulse or repetition time (TR), longitudinal or spin-lattice relaxation (T1), and spin–spin relaxation (T2).

The majority of soft tissue tumors have a low signal intensity (i.e., appear darker) on T1-weighted scans and a high signal intensity (i.e., appear brighter or whiter) on T2-weighted studies. Specific problems, such as hematoma, lipoma (or liposarcoma), hemangioma, or conditions that involve hemorrhage into an existing tumor zone, are known to have high signal intensity on Tl-weighted scans. Obviously, the potential value of MRI is diminished in a region recently subjected to biopsy, trauma, or other surgery.

MRI is a superior imaging technique for assessment of the soft tissue extent of disease and is particularly beneficial in the evaluation of soft tissue sarcoma. The extent of intramedullary bone involvement also can be readily determined. This facilitates preoperative planning of the bone transection level during resection and may aid in identification of skip metastases that might otherwise not be identified. High-resolution CT offers the benefit of more accurate assessment of cortical bone involvement and may be the preferred technique for evaluating lesions involving the cortex of a given bone. CT is particularly beneficial in identifying occult osteoid osteomas.

Sonography

Sonograms produce images from a differential pattern of transmitted and received echoes. When compared with CT and MRI, sonography produces less detail with respect to precise anatomic relationships and tumor margins. The echo patterns of solid masses are nonspecific, but fluid-filled lesions can easily be differentiated from solid tumors. Sonograms are extremely inexpensive in comparison to the cost of CTs and MRIs and may be more useful than either for distinguishing reactive and cystic processes. Ultrasound guidance can be particularly useful for core needle biopsy of soft tissue lesions.

Needle Biopsy

Core needle biopsy has a limited role in the diagnosis of lesions in the hand and upper extremity. It can be useful in the assessment of subcutaneous lesions or in confirming the histology of a recurrent or metastatic lesion. Needle biopsy produces only a small and often fragmented tissue sample that may be impossible to diagnose or grade accurately. Even if the core biopsy sample seems to clearly be diagnosable, the tissue volume may not be representative of the tumor and could lead to the possibility of overgrading or undermanagement.

Open Biopsy

Open surgical biopsy is a complex procedure, but one that plays a critical role in determining treatment outcome for aggressive and malignant tumors. During the biopsy, the patient and surgeon must be prepared for the unexpected. Institutions or clinicians who are not prepared or able to complete all diagnostic studies and also provide definitive surgical and adjunctive medical management are best advised to refer patients before the biopsy is performed.

Hand surgery is most safely and efficiently performed in a bloodless field. The use of a pneumatic tourniquet is acceptable during both open biopsy and surgical treatment of tumors and neoplasms. Exsanguination of the limb before biopsy is contraindicated before inflation of the tourniquet because of the risk of seeding or dislodging tumor cells. An entirely satisfactory field is achievable by elevating the arm for 1 to 2 minutes before inflating the tourniquet. Likewise, the use of intravenous anesthesia (i.e., Bier block technique), a method that also requires pretourniquet exsanguination, is not appropriate for tumor biopsy or treatment of aggressive bone or soft tissue neoplasms.

A frozen section is necessary at the time that the biopsy is performed to determine whether an adequate specimen has been sampled so that permanent light and special microscopic evaluations can be carried out subsequently. It is rare to find a pathologist who can consistently provide accurate histologic analysis of a frozen specimen dependable enough to begin treatment. The definitive treatment plan for malignant lesions is best decided on only after the results of all permanent sections, electron microscopic studies, and special tissue techniques are complete and reported. All biopsy specimens should be cultured, and all cultures should have tissue sent for microscopic examination.

Although plain chest radiographs are taken before biopsy, chest CT is performed to stage a diagnosed lesion. If the tumor is aggressive or malignant, the biopsy tract itself will be contaminated with tumor cells and must later be excised en bloc with the subsequent resection or amputation specimen. Preferred biopsy incisions are therefore longitudinal and carefully placed to permit complete excision of them without having to extend a dissection margin simply to accommodate a badly placed incision. As a simple rule, the biopsy should be placed in line with or immediately parallel to the incision that may be required for later attempted limb salvage ( Figure 59.2 ). Transverse and Bruner-type incisions are specifically to be avoided.

An open incisional biopsy was performed for a hand lesion. The biopsy site is contaminated with tumor cells (A) ; the incision is oriented longitudinally and will be excised as part of the definitive procedure performed later (B) .

Incisional Biopsy

Incisional biopsy is frequently the most appropriate technique for the diagnosis of bone and soft tissue masses. It requires excision of an adequate tissue sample that is minimally manipulated. Frozen sections are important to determine the adequacy of the specimen. The biopsy incision is located so that it affords the most direct route to the tumor, thereby ensuring that the fewest tissue planes are disturbed or contaminated.

The correct surgical technique for biopsy is different from standard typical surgical dissections. Biopsy involves a direct approach using a longitudinal incision through muscle and other tissues that overlie the mass. Biopsy technique does not include spreading or extensive and vigorous retraction, which has the potential to contaminate a widened area. However, adequate visualization during biopsy, as in any operation, is critical. Because the biopsy tract is contaminated with cells, an approach through a muscle sacrifices only one plane, whereas spreading techniques (i.e., moving muscles aside) contaminate not only the muscle that is retracted but also all surrounding structures. Perfect postsurgical hemostasis is essential to avoid hematoma, which can lead to the spread of cells beyond the primary site and biopsy tract. Once the wound is dry and hemostasis is secure after release of the tourniquet, the wound is closed, not drained. Other than taking steps to avoid pathologic fracture, postbiopsy surgical care is routine while the surgeon awaits the definitive histologic findings.

Excisional Biopsy

Excisional biopsy involves complete removal of a lesion through the reactive zone. An example would be excision of a giant cell tumor of a tendon sheath or a lipoma. It is a technique that should be reserved for very small lesions (with a diameter of <1-2 cm) to avoid compromising subsequent surgical procedures. Extensive contamination of the operative field occurs with this type of biopsy. If this is done for a large tumor, the extent of contamination may increase the need for soft tissue coverage and increase the risk for both positive margins at definitive resection and subsequent local recurrence. Extensive contamination may preclude subsequent limb salvage and may commit the patient specifically to amputation as a result of the biopsy.

Primary Wide Excision

This type of biopsy requires excision of the tumor with a wide margin or cuff of surrounding normal, nonreactive, healthy tissue. This is an excellent oncologic procedure but requires sacrifice of an extensive amount of normal tissue. Primary wide excision is usually best reserved for very small lesions in which suspicion of malignancy is high and the risk of soft tissue contamination with other forms of biopsy is excessive, as might occur in the carpal tunnel. The decision of when to perform this type of biopsy is generally best made with the assistance of or by a musculoskeletal oncologist.

Benign Tumors

Nonaggressive, benign neoplasms are usually removed simply by marginal or intralesional operations such as curettage. If there is a question about the adequacy of resection of the tissue margins and the diagnosis is already confirmed, a frozen section may be of great assistance for intraoperative sampling of the margins.

Malignant Tumors

In the management of malignancies of the upper limb, preservation of function is secondary to eradication of the disease process. Hand surgeons who undertake management of a neoplasm must have a thorough understanding of the tumor’s biologic behavior, its patterns of local and metastatic spread, and its response to radiotherapy and chemotherapy. Radiation therapy and chemotherapy may allow the surgeon to use less radical tumor margins so that amputation can be avoided and function maintained. However, the risk of unnecessary sacrifice of tissue must be balanced against the need for adequate resection because local recurrence of sarcoma sometimes carries a grave prognosis. One of the major problems in assessing outcome has been the lack of a common procedural language regarding surgical methods; however, uniform use of the Enneking terminology, as recommended by the MSTS, provides such a means of communication (see Table 59.2 ).

Treatment should not begin until a neoplasm has been diagnosed definitively and the results of all preoperative studies, including biopsy, are verified. The assumption that a problem can be “handled” by relatively simple extirpation in the absence of complete diagnostic data is neither justified nor defensible. The risks associated with soft tissue extension from a tumor-contaminated field are too great. Because most tumors are benign, cystic, and nonproblematic, the outcome of the few that are aggressive or truly malignant may be disastrous if surgeons become too casual or complacent. When a malignant tumor or aggressive nonmalignant lesion is identified, carefully planned treatment is required not only to preserve the maximal degree of hand function but also to save the patient’s life. Function is secondary to survival.

Hand surgeons who seek to treat a specific neoplasm must have not only a general understanding of the concepts and principles of tumor management but also detailed knowledge of the tumor’s biology, histologic and clinical behavior, tendency to spread locally and widely, and potential response to adjunctive measures. All these considerations can have a significant bearing on proposed surgical margins and long-term function. An inadequate resection that permits local recurrence may condemn the patient to a far worse prognosis than would otherwise have occurred.

According to MSTS criteria, compartmental resection and radical excision cannot always be applied to the hand. Most hand tumors occur in spaces rather than in compartments, and although metacarpal excisions may remove a compartment for a stage IA or IIA bone tumor, extirpation of the entire flexor surface or above-elbow amputation would be required to remove the compartment if the neoplasm arose on a digital flexor. Presently, there are no data to support a conclusion that the MSTS definitions should be applied uniformly to all parts of an acral compartment. Because the flexor tenosynovium is continuous in the thumb and little finger, but not in the index, middle, and ring fingers, there may be differences in management that can be used prudently with such variations in location.

A soft tissue tumor that develops along the dorsum of the wrist requires surgical extirpation of the extensors of several fingers or the thumb (or both), but not necessarily the entire muscle compartment proximally or distally. Functional restoration can be achieved with tendon grafts or transfers or with free muscle flaps. True radical excision may be impractical if function of any kind is to be salvaged in patients with lesions of the hand and forearm, and it may be that a 1- to 2-cm margin of normal tissue, especially with tumors that are sensitive to adjunctive measures, will be safe and allow secondary reconstruction. The extent of surgical resection for aggressive tumors is dependent on their histologic diagnosis, location, and size. Remote tissue reconstruction, except when provided by microvascular transfer, should be avoided because of the risk of transferring malignant cells using tissue or flap pedicles.

Distal Phalanx

Malignant soft tissue tumors in the distal phalanx commonly involve skin and bone ( Figure 59.3 ). Safe removal may require excision at the distal interphalangeal (DIP) joint; occasionally, a lesser segment may need to be excised when the lesion, such as a nail bed carcinoma, is more superficial and slow growing. A small portion of dorsal or palmar skin might be used as a local flap to cover the middle phalanx after disarticulation of the DIP joint. In such instances, the distal phalanx and DIP joint are sacrificed if the lesion involves or threatens enough tissue while retaining the tissues at a safe distance from the tumor site. Indeed, if the tumor involves both the dorsal and palmar surfaces of soft tissue as well as bone, a more proximal transosseous amputation through the middle phalanx is required. In every case, the proximal end of the excision margin should be sampled and inspected by frozen section at surgery and later by permanent-technique histology to ensure the safety of the level of removal.

Malignant lesions of the terminal segment of the finger generally require amputation at or proximal to the DIP joint. A, Intraosseous distal phalangeal tumors are amputated at or proximal to the joint along with combined dorsal and volar flap closure. B, Dorsal lesions are treated by appropriate tumor excision with volar flap closure. C, After removal of a palmar tumor, dorsal flap closure may be possible.

Malignant distal phalangeal lesions require removal with an appropriate cuff of contiguous soft tissue. Lower-grade bone tumors can be managed by distal phalangeal amputation that includes a soft tissue cuff 1 to 2 cm proximal to the intraosseous tumor, a level that requires transosseous resection through the middle phalanx. It is unlikely that such lesions can be safely removed by DIP disarticulation alone. Patients with pathologic fractures or extracompartmental extension usually require removal of the finger at or proximal to the proximal interphalangeal (PIP) level or even ray resection.

Middle Phalanx

Malignant and aggressive soft tissue tumors in the middle phalanx and those proximal to the region of the DIP joint require amputation at the metacarpophalangeal (MP) joint or metacarpal level or ray resection ( Figure 59.4 ). In this instance, MP joint disarticulation should allow at least a 2- to 3-cm margin of normal tissue; however, functional and aesthetic considerations strongly recommend ray resection ( Figure 59.5 ). In theory, bone tumors involving the proximal and middle phalanges can be excised and replaced with bone graft if the lesion is not aggressive and has not extended into soft tissues. However, ray resection is actually a far more practical and functional alternative if both the proximal and middle phalanges are involved. For malignant tumors that have spread beyond bone because of fracture or slow, progressive extension, ray amputation is clearly indicated. MP joint disarticulation is rarely a safe, practical, functional, or aesthetic choice for treating tumors at these levels.

Tumors of soft tissue at the middle phalangeal and proximal interphalangeal joint level are best treated by ray resection.

A, Axial magnetic resonance imaging demonstrating synovial sarcoma following radiation involving third and fourth metacarpal. B, Fourth ray resection was performed with en bloc resection of the diaphyseal third metacarpal. C, D, Volar and dorsal incisions for ray amputation and fillet flap marked. Dorsal biopsy tract is incorporated into the dorsal incision. E, F, Intraoperative resection. G, H, Appearance at closure. I, Postoperative radiograph demonstrating third metacarpal reconstruction using fibula graft.

Thumb lesions are unique. Although lesions distal to the interphalangeal joint are often best treated by amputation, lesions at the proximal phalanx level may be amenable to wide excision and extensive reconstruction. This can be done safely while adhering to the principles of wide excision and subsequent extensive reconstruction, which may require bone and microsurgical soft tissue reconstruction.

First Metacarpal

First metacarpal malignancies can be treated by wide excision and autogenous or allograft replacement ( Figure 59.6 ). Achieving wide margins may require excision of surrounding soft tissues and adjacent joints or bones. Reconstruction with metacarpal allograft, or by fibula or iliac autograft, may be considered in appropriate circumstances. Autografting should be done with a second, separate surgical setup and clean gowns and gloves to avoid cross contamination of the bone donor site. Because osteoarticular allografts may be unstable, arthrodesis may be required at the trapeziometacarpal articulation. Alternatively, suspension may be appropriate if trapezium resection is required.

A, A grade 3 giant cell tumor (GCT) of the thumb metacarpal is treated with wide extraarticular resection including the trapezium and base of the proximal phalanx. B, Thumb metacarpal is reconstructed with a large iliac crest graft with metacarpophalangeal joint arthrodesis and proximal suspension. C, Long-term follow-up of diaphyseal segment reconstruction using iliac crest bone graft for a grade 2 chondrosarcoma. Small blade plates facilitate internal fixation of small periarticular fragments.

With extensive soft tissue contamination, more radical resection may be required, including the entire first ray and possibly portions of the web and second metacarpal, to gain a safe margin. If part of the second metacarpal is resected, the “floating index finger” thereby produced can be considered for direct pollicization if sacrifice of the entire second ray is not required.

Finger Metacarpals

Aggressive and malignant bone tumors of the second through fifth metacarpals generally require en bloc bone excision. A more important treatment decision may be whether removal of one metacarpal alone is possible or whether removal of an entire ray or pair of rays is best. Ray excision is usually best for lesions of the second and fifth metacarpals ( Figure 59.7 ). With the additional consideration of ray transposition, the principles governing removal of the third and fourth rays are no different from those governing the second and fifth. If bone graft has been used for reconstruction, carpometacarpal arthrodesis and MP ligament reconstruction or silicone arthroplasty may be practical. Whatever level is chosen for reconstruction, it is essential that an adequate, safe margin of normal tissue first be excised en bloc with the tumor.

Malignant tumors of the fifth metacarpal can be treated by ray excision.

Aggressive tumors of the second through fifth metacarpals that have invaded soft tissue or sustained pathologic fractures often require excision of not only the involved ray but also the contiguous ray or rays radial and ulnar to the involved digit. A malignant tumor of the second metacarpal that extends into soft tissues may necessitate removal of the second and third rays or the first through third rays while preserving the soft tissue of the middle finger as a fillet flap to resurface the radial side of the hand. A similar technique can be used for tumors of the ulnar side of the hand. If the second, third, and fourth rays must be removed, the best strategy is usually to osteotomize and supinate the fifth metacarpal to provide effective oppositional pinch and grasp with the thumb. If a tumor of the fourth metacarpal requires removal of the third through fifth rays, the radial aspect of the middle finger or a fillet of that digit on its radial neurovascular pedicle can be used to close the ulnar side of the hand. Tumors of the fifth metacarpal may require excision of the fourth and fifth rays. Skin coverage may be possible by using a fillet flap from the ring finger.

If a malignant tumor has broken into the midpalm and extends across the metacarpals, removal of all digital rays may be needed to gain an adequate soft tissue margin. Retention of a sensate and relatively mobile thumb may be considerably more aesthetic and functionally satisfactory than a forearm- or wrist-level amputation. However, if a tumor extends proximally from the metacarpal level, a more proximal level of hand, wrist, or forearm amputation is required for safe tumor management.

Soft tissue tumors in the palm or on the dorsum of the hand generally require at least partial hand amputation. If treated by only local or limited excision, the chance of recurrence and metastasis may be enhanced; below-elbow amputation is necessary to treat these larger tumors. It is unusual for an aggressive soft tissue tumor to be adequately removed by a truly local en bloc excision. At a minimum, aggressive soft tissue tumors, such as bone tumors, require ray resection or removal of multiple rays ( Figures 59.8 through 59.10 ). Central palmar lesions generally require sacrifice of three rays; those on the border are more likely than those in the center to be salvageable by removing just two rays. In the presence of proximal, broader, and larger lesions, all four digits or the entire hand may have to be sacrificed to save the patient.

Malignant soft tissue tumors adjacent to the thumb metacarpophalangeal joint require amputation through the metacarpal. More aggressive and extensive tumors may require removal of the entire ray, possibly contiguous with the second metacarpal.

A, Tumors located between the first and second metacarpals may require amputation of both rays for adequate local control. B, Tumors between the second and third metacarpals require removal of both rays. C, Lesions of the ulnar border of the hand can be treated by resection of the fifth ray and local flap or skin graft closure. D, Large and more aggressive lesions or those extending more radially may need removal of both the fourth and fifth rays.

A, B, Magnetic resonance imaging coronal and axial views of a rapidly progressing malignant peripheral nerve sheath tumor. C-G, Wide excision required double ray resection of the central rays. H, I, Immediate postoperative appearance.

Wrist and Distal Forearm

Malignancies of the proximal palmar surface of the hand and volar aspect of the wrist often require amputation. A dissection that attempts to “salvage” the median nerve or one or two flexors in the middle of an expanding tumor or reactive zone is only likely to spread the disease. Correct surgical and medical principles for tumor removal and care should be taken ( Figures 59.11 through 59.13 ).

A, Tumors on the proximal volar aspect of the palm often involve the flexor tendons and median and ulnar nerves; forearm- or wrist-level amputation is usually required. B, Lesions on the dorsum of the hand may not necessarily invade vital neurovascular structures and can be adequately resected en bloc, followed by secondary reconstruction.

A-C, A myxofibrosarcoma of the thumb with extensive infiltration into the hand rendering hand salvage impossible. D, E, The patient was treated by below-elbow amputation.

Aggressive tumors of the radial side of the distal part of the forearm may require amputation of the thumb and index rays, as well as the contiguous radial side of the wrist at a minimum.

Tumors that arise on the dorsum may allow preservation of the hand if staging studies show that the lesion has not penetrated into the palm and the excision margin verifies a safe plane of normal tissue. Isolated intraosseous carpal lesions that have not invaded soft tissue are rare but can be excised locally. The carpal bones are intraarticular, so the onset of symptoms is generally associated with synovitis and joint invasion; therefore, below-elbow amputation or complete en bloc excision of the entire radiocarpal articulation and carpus is likely to be necessary.

Growths on the volar aspect of the distal part of the forearm frequently require above- or below-elbow amputation because it is not easy to excise a tumor adequately and still preserve function in and distal to this region after removal of all flexor muscles and tendons, the median and ulnar nerves, and vessels. If a tumor arises in a location that does not specifically involve the ulnar nerve and artery, it may be possible to save a portion of the hand and wrist along with the neurovascular bundle and to consider later reconstruction after longitudinal hemiamputation. Treatment of tumors arising on the radial side of the distal end of the forearm varies according to the size and exact location of the lesion ( Figure 59.14 ). In many situations, as is true of lesions on the volar side, amputation is probably preferable when all criteria are considered. Tumors on the extreme ulnar side of the wrist can be handled in a way that mirrors those on the radial aspect, although lesions in the extreme end of the ulna may be amenable to wide excision of the distal ulna ( Figure 59.15 ).

A, Radiograph of giant cell tumor of bone involving the distal radius. B, Radius and ulna have been transected and entire segment is everted to facilitate volar dissection. C, Extraarticular resection is completed by disarticulating at the midcarpal joint. D, Intercalary arthrodesis is performed using a vascularized osteoseptocutaneous fibula. E, Radiograph following healing.

A, Intraosseous tumors of the distal ulna can be managed by en bloc excision. No bone reconstruction is needed in most cases. Tumors with soft tissue extension (B, C) may require excision of the ulnar cortex of the radius en bloc with the ulna, as was required with this malignant fibrous histiocytoma. D, A portion of the remaining ulna was used to augment the radius and support the lunate facet.

Intracompartmental lesions within the distal radius or ulna can be treated by wide excision of the bone and arthrodesis or autograft replacement. In such situations, transosseous excision must include biopsy of the medullary canal from the retained segment or segments. When tumors have invaded tissues or crossed compartments extensively, above- or below-elbow amputation may be required.

Wherever a tumor is located, treatment must be individualized to achieve the goal of functional restoration without risking local recurrence and later distant spread. Because of a lack of control over the site and the origin of the neoplasm, the surgeon’s responsibility is confined to intelligent management and treatment by adhering to the proper principles of care.

Clinical Characteristics

Ganglion cysts are the most common soft tissue tumors of the hand. These mucin-filled cysts are usually attached to the adjacent underlying joint capsule, tendon, or tendon sheath. Ganglions are most prevalent in women and generally occur (70%) between the second and fourth decades of life. They are not rare in children and have been reported from the first to the eighth decades. Ganglions usually occur singly and in very specific locations; however, they have been reported to arise from almost every joint of the hand and wrist ( Table 59.4 ). The less common ganglions are often associated with other conditions of the hand (e.g., bossing of the second and third carpometacarpal joints, de Quervain disease, and Heberden nodes of the DIP joint).

Ganglion cysts have also been reported to cause clinically symptomatic pressure on the median and ulnar nerves of the hand. Because of their high incidence and prevalence, ganglion cysts should readily be recognized by most hand surgeons. Other conditions that cause diffuse swelling over the dorsum of the wrist, such as extensor tenosynovitis, lipomas, and other hand tumors, also must be considered in the differential diagnosis. The history, physical examination, techniques of transillumination, and aspiration should allow a conclusive diagnosis in most instances.

Patients usually seek medical attention because of the cosmetic appearance of the mass, pain, weakness, and concern for potential malignancy. A specific antecedent traumatic event is present in at least 10% of cases, and repeated minor trauma may be an etiologic factor in their development. There is no obvious correlation with patient occupation. Malignant degeneration has never been reported; however, malignant soft tissue tumors are frequently misdiagnosed as ganglion cysts. Gan­glions can appear quite suddenly or develop over a period of several months. They may subside with rest, enlarge with activity, and rupture or disappear spontaneously. Although recurrences are infrequent with proper excision, >50% may recur if incompletely excised.

Radiographs of the involved region are often unremarkable, although intraosseous cysts are occasionally present at the wrist. Osteoarthritic changes are commonly seen with cysts at the DIP or carpometacarpal joints. Communication between the wrist joint and cyst has been demonstrated with arthrograms but not with cystograms. A one-way valvular mechanism has therefore been postulated to connect the wrist joint to the cyst.

Pathogenesis

Since Hippocrates offered the first recorded description of “knots” of tissue containing “mucoid flesh,” numerous speculative theories with little scientific basis have abounded. This became especially apparent when 18th- and 19th-century anatomists offered the following hypotheses: (1) synovial herniation (Eller, 1746) or rupture through the tendon sheath, (2) synovial dermoid or rest caused by “arthrogenesis blastoma cell nests” or embryonic periarticular tissue (Hoeftman, 1876), (3) new growths from synovial membranes (Henle, 1847), and (4) modifications of bursae or degenerative cysts (Vogt, 1881).

Until recently, the most widely accepted theory, initially postulated by Ledderhose (1893) and popularized by Carp and Stout, was mucoid degeneration. The fibrillation of collagen fibers, accumulation of intercellular and extracellular mucin, and decreased collagen fibers and stroma cells supported this theory. Mucoid degeneration does not, however, explain why the degenerative process is self-limited and solitary and generally occurs in adolescents and young adults and why the fluid recurs after aspiration or incomplete excision.

Nonoperative Treatment

Nonsurgical methods of treatment are usually considered initially because of the limited associated morbidity and possibility of success. Nonsurgical treatment has included digital pressure, injections of hyaluronidase or sclerosing solutions, subcutaneous tenotome dissection, and cross fixation with a heavy suture. Historical folk medicine has mentioned rupture with a mallet or Bible, methods that need not be considered except for their historical interest. Observation has been advocated in the pediatric population because of the high likelihood of spontaneous resolution.

Aspiration of the ganglion, puncture of the cyst wall, and instillation of lidocaine (Xylocaine) and betamethasone (Celestone) into the capsule or tendon sheath attachments reduce the mass and may alleviate symptoms for varying periods. Aspiration may provide long-term relief and has been reported to be effective in 20 to 30% of patients with wrist ganglions. Injection and aspiration of volar wrist ganglions must be approached with caution because of the proximity of the radial artery. Marked subcutaneous atrophy and skin depigmentation may be seen after injection with triamcinolone (Kenalog), which should be avoided.

The most effective nonsurgical treatment is patient reassurance. An explanation of the condition and assurance of its nonmalignant nature are often the only treatment sought or required. Surgery is best reserved for patients with persistently symptomatic ganglions.

Operative Treatment

Open procedures are most commonly done for excision of ganglion cysts. Treatment principles include attempts to minimize scar formation and loss of range of motion. Data on arthroscopic approaches to both dorsal and volar carpal ganglion cysts have been published. The technique appears to be effective with a risk for local recurrence comparable to the historic risk for recurrence after open procedures. Recent comparative studies have evaluated the relative risks and benefits of open versus arthroscopic treatment and demonstrated similar outcomes.

Dorsal Wrist Ganglion

Clinical Characteristics.

The prototype of all ganglions of the hand is the dorsal wrist ganglion, which accounts for 60 to 70% of all hand and wrist ganglions. The main cyst is usually located directly over the scapholunate ligament ( Figure 59.16 ) and is easily seen and diagnosed. The cyst may occur anywhere else between the extensor tendons, however, and can be connected to the ligament through a long pedicle (see Figure 59.16 ). Failure to identify this pedicle and excise its attachment to the scapholunate ligament increases the likelihood of recurrence. Careful preoperative palpation of the cyst with digital compression often reveals its extent and the direction of the pedicle. Transillumination or aspiration confirms the diagnosis preoperatively. Although ganglions have been reported in other carpal joints, they are rare and attachments to the scapholunate joint must be ruled out before a dissection is considered complete. Review of the patient’s preoperative radiographs to rule out an interosseous component is wise.

A few of the many possible locations of dorsal wrist ganglions. The most common site is directly over the scapholunate ligament. The others ( dashed circles ) are connected to the scapholunate ligament through an elongated pedicle.

(Copyright © Elizabeth Martin.)

Author’s Preferred Method of Treatment

Operative Technique.

Most dorsal ganglions can be approached through a transverse incision over the proximal carpal row, but a modified incision or second transverse incision may be necessary for ganglions not directly over the scapholunate ligament ( Figure 59.17 ). The diagnosis of ganglion cyst should be made before commitment to a transverse incision because this type of incision is not readily incorporated into a limb-sparing incision in the event of a subsequent diagnosis of a malignant soft tissue tumor. Typically, a dorsal ganglion appears between the extensor pollicis longus and extensor digitorum communis tendons, which are retracted radially and ulnarly, respectively ( Figure 59.18 ).

Transverse incision over the scapholunate ligament (A) used to expose the typical dorsal ganglion. An additional incision (B) was made to expose a more distant cyst. The main cyst and pedicle are mobilized, passed under the extensor tendons, and delivered through incision at A .

(Copyright © Elizabeth Martin.)

The dorsal ganglion exposed and mobilized between the extensor pollicis longus (EPL), extensor carpi radialis longus (ECRL), and extensor carpi radialis brevis (ECRB) radially and the extensor digitorum communis (EDC) and extensor indicis proprius (EIP) ulnarly.

(Copyright © Elizabeth Martin.)

The main cyst and its pedicle are mobilized down to the underlying joint capsule. With the wrist in volar flexion, the joint capsule is opened along the border of the radius and scaphoid’s proximal pole ( Figure 59.19 ). The capsule is elevated and retracted distally to expose the capsular attachments to the scapholunate ligament ( Figure 59.20 ). Smaller intraarticular cysts are often seen attached to the scapholunate ligament. The capsular incision is then continued around the ganglion, but all capsular attachments to the ligament are left intact ( Figure 59.21 ). The capsular incision is extended more laterally if any capsular ducts, which can be identified by small amounts of mucin drainage, are encountered during the dissection. The ganglion and its capsular attachments are then tangentially excised off the scapholunate ligament ( Figure 59.22 ).

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