Fractures of the Metacarpals and Phalanges

Treatment for Closed Reduction of Metacarpal Neck Fractures and Casting

Jahss recognized that flexing the MCP joint to 90 degrees relaxed the deforming intrinsic muscles and tightened the collateral ligaments, thereby allowing the proximal phalanx to exert upward pressure on the metacarpal head. He applied a cast in two parts, first immobilizing the proximal metacarpal fragment and then flexing the MCP and PIP joints and pushing upward on the flexed PIP joint while applying the second part. He reported 10 cases with uniformly satisfactory results. This reduction method gained wide popularity, but the casting method has since largely been abandoned because persistent PIP stiffness or skin necrosis developed over the dorsum of the PIP joint in some patients. The “Jahss maneuver” today remains an excellent technique of closed reduction ( Fig. 7.3 ); however, the small finger should never be immobilized in the “Jahss position” with both joints flexed 90 degrees. In fact, the traditional dogma of always immobilizing the MCP joint in flexion has recently been challenged with respect to small finger metacarpal neck fractures. In 81 active-duty military patients, no difference was found with respect to maintaining reduction, range of motion, grip strength, or DASH scores between those managed with the MCP joints flexed or extended in the cast; though the authors noted easier cast application with the MCP joint extended. Similarly, Tavassoli et al. retrospectively found no difference in range of motion, grip strength, or final fracture alignment based on the position of immobilization in 263 patients.

Closed Reduction and Pin Fixation

Closed reduction with percutaneous pinning was reported first by Bosworth in 1937 and remains a popular method of treatment for metacarpal neck and shaft fractures. Pinning can be performed in either an antegrade, retrograde, or transverse manner, with a single or multiple pins and with the pins buried or left exposed. Percutaneous pinning has the advantage of being simple, less expensive, and minimally invasive, and should reduce the likelihood of postoperative swelling and stiffness that frequently follows open reduction and internal fixation. The disadvantages are that it does not provide rigid fixation and some form of external immobilization is necessary, and it carries the risk of pin site infection especially when pins are left exposed and the potential need for an additional operation for pin removal if they are buried. In terms of the direction of pin placement, two studies have demonstrated superiority of an antegrade open technique in the short term (less than 3 months) but no benefits of one technique over the other by 6 months. ^,

Foucher has reported excellent results with the use of “bouquet” osteosynthesis in the management of displaced small finger metacarpal neck fractures. The fracture is reduced in closed fashion, holes are made in the proximal ulnar metaphysis of the metacarpal, and three blunt prebent Kirschner wires are passed antegrade down the medullary canal, across the fracture, and into the subchondral bone of the metacarpal head ( Fig. 7.4 ). This has the advantage of avoiding the fracture site but can be technically difficult and pins can migrate either proximally or distally. A variation to this technique is the use of a single, larger intramedullary (IM) wire for fixation, which has been shown to be noninferior and less technically demanding. ^, In a prospective, multicenter randomized study of 85 patients with a minimum of 30 degrees of angulation of small finger metacarpal neck fractures, no difference was found between closed reduction with bouquet pinning and nonoperative treatment without reduction in terms of quick-DASH, pain, range of motion, grip strength, or quality of life at 1 year. In terms of comparing IM pinning versus percutaneous transverse pinning, the literature is conflicting with studies showing no difference in outcome, ^, faster operative time and lower complications with transverse pinning, and superior outcomes with IM pinning.

Open Reduction of Metacarpal Neck Fractures

Open reduction is indicated when manipulation fails to restore acceptable rotational alignment or at times for specific patient factors such as intolerance of immobilization. In terms of angulatory malalignment, most studies have failed to demonstrate the superiority of operative treatment for these fractures, and no consensus regarding the upper limits of displacement have been established; therefore surgery should be approached with caution, weighing the risks and benefits carefully. Methods of achieving osseous stability with internal fixation include pinning, IM Kirschner wires, IM screws, or plate fixation.

From a biomechanical standpoint, fixed-angle plating has been shown to provide increased stiffness and stability compared with nonlocked plating, crossed Kirschner wires, and IM screw fixation ^, ; although clinically, plating is more invasive. IM screw fixation and crossed Kirschner wires have been shown to be biomechanically similar and offer a less invasive approach.

Plate fixation has been used for over 50 years for metacarpal neck fractures. Initial straight plates evolved into an L- or T-plate to maximize fixation in the metacarpal head. ^, Modern plates with variable angle locking screw clusters offer superior stability of metacarpal head fixation compared with traditional locking and nonlocking plates. They also offer the theoretical clinical advantage of decreased operative dissection, given the clusters of screw holes within a short span. While locking plates provide the necessary rigid fixation to allow early range of motion and good outcomes in many cases, the risk of joint or tendon adherence and hardware prominence that may necessitate removal remain concerns.

Since it was first reported in 2010, IM screw fixation has emerged as a popular technique for managing metacarpal neck fractures. This procedure can be performed through a minimally invasive, extensor-splitting or extensor-sparing approach at the MCP joint with insertion of a retrograde IM screw ( Fig. 7.5 ). Proposed advantages include sufficient biomechanical strength to allow immediate and nonprotected range of motion, minimal soft tissue dissection, lessened risk of tendon adhesions, no prominent hardware, and decreased rate of hardware removal. Recent reports have demonstrated excellent radiographic and clinical outcomes. A 2019 metaanalysis by Beck et al. of nine articles and 169 patients found 100% union, 96% grip strength, 86 degrees MCP flexion, and no serious complications. While this retrograde approach does violate the articular surface of the metacarpal head, this has not been shown to be of clinical significance. Three-dimensional quantitative CT analysis has demonstrated even in maximal MCP extension, only 12% contact exists between the base of the proximal phalanx and the screw entry point given the dorsal insertion site of the screw ( Fig. 7.6 ).

Malunion

Unless there is significant impairment of motion or pain, a malunion of the fifth metacarpal neck is usually well tolerated. In rare cases of symptomatic malunion, osteotomy can be considered. Hoigne et al. utilized a dorsal closing wedge osteotomy to correct angular malunion and achieved acceptable clinical results but noted metacarpal shortening in all cases. Thurston reported good correction in 9 of 10 metacarpal neck osteotomies with a two-cut “pivot” osteotomy. This combined the benefits of an opening wedge osteotomy (no shortening) and a closing wedge osteotomy (no bone graft or tension on soft tissues). Zhang et al. reported similar success in 21 cases using a simple palmar opening wedge osteotomy secured with three transverse Kirschner wires, cancellous bone graft, and no immobilization.

Closed Management

Closed reduction with immobilization works well for the majority of metacarpal shaft fractures, and overtreatment is to be avoided. Many metacarpal fractures are inherently stable and may be treated with minimal or no immobilization. For example, in athletes, Rettig et al. reported that 82% of the fractures were minimally displaced or nondisplaced and the average time lost from practice or competition was only 13.7 days. McMahon et al. treated stable metacarpal fractures with either a compression glove or 3 weeks of immobilization. Although the final ranges of motion were comparable, those in the elastic garment had better mobility and less swelling. Wright observed that over 60% of patients with fractures of metacarpals that were immobilized for more than 3 weeks had significant loss of hand function. When short-term casting is employed, the wrist is placed in slight extension, MCP joints flexed, and the PIP joints are extended. The hand assumes the intrinsic-plus or “clam-digger” position ( Fig. 7.8 ). This position limits joint contractures and maintains the intrinsics in a relaxed position. Functional braces have been designed to provide three-point fixation of the fracture and allow mobility of the wrist and fingers. Some have found braces ineffective and others found that if the brace was applied too tightly, skin necrosis could occur.

Closed Reduction and Percutaneous Pinning

Closed reduction and percutaneous pinning remains a time-tested and acceptable technique for the management of metacarpal fractures, and recent studies continue to demonstrate acceptable functional outcomes, low DASH scores, and high union rates. ^, Kirschner wires may be used in nearly any fracture pattern ( Fig. 7.9 ). Kirschner wire fixation is technically easy, requires minimal dissection, and is universally available. Wire configurations can be either single or multiple and may be crossed, transverse, longitudinal (IM described above), or in combination. They can be used to supplement other forms of fracture fixation and can also be used as a “bailout” if more complicated fixation has failed. On the other hand, Kirschner wires are not rigid, may loosen or even migrate, and have the potential to distract fracture fragments. Furthermore, pin tract infections may develop secondary to skin irritation or loosening, and pin protrusion may make therapy and splintage awkward. Alan Freeman aptly stated that Kirschner wires first penetrate, then incinerate, then irritate, and finally suppurate (personal communication). Botte et al. reviewed a series of 422 Kirschner wires placed in the hand and wrist and reported an 18% complication rate. In a series of 590 Kirschner wire fixations, Stahl and Schwartz noted a 15.2% complication rate. The majority were classified as minor (pin loosening, infection, or bending); however, 1.7% were major (osteomyelitis, tendon laceration, or nerve injury). There was no difference between protruding or buried pins. Most of the complications were not serious, and permanent sequelae were infrequent.

For longitudinal fixation, the pin can be drilled in retrograde fashion from the fractured end out the dorsoradial aspect of the metacarpal head and then back down the shaft through the reduced fracture. Following fracture reduction, a pin can also be introduced directly into the metacarpal head on either side of the extensor tendon and driven down the metacarpal shaft to engage subchondral bone at the CMC joint. Transarticular pins are generally bent outside the skin and left in place for 3 weeks. An alternative, but technically more difficult, method is to percutaneously introduce the Kirschner wire through the lateral aspect of the metacarpal head in the area of the collateral ligament origin and then down the shaft. This technique is indicated primarily for transverse and short oblique shaft fractures. A recently described technique of combining percutaneous pinning with an external connector to enhance construct stability has been described demonstrating comparable results to plating and IM pinning. ^,

Closed or Limited Open Reduction and Intramedullary Fixation

To avoid complications related to a protruding pin or extensor tendinopathy, IM Kirschner wire fixation for unstable metacarpal fractures was introduced. ^, IM fixation is applicable for transverse and some oblique fractures, is easy to perform, allows for early active motion, and makes secondary removal unnecessary. Often this can be performed in a percutaneous or limited open fashion; however, open reduction is required if an acceptable reduction cannot be obtained. In 1981 Grundberg reported one nonunion in 27 metacarpals treated by open reduction and permanent IM fixation with a large Steinmann pin. Potential disadvantages include rotational instability, pin migration, and occasional fracture distraction. The technique is particularly ill-suited for spiral or long oblique fractures given their inherent rotational instability.

In an effort to better control rotation, a technique of closed IM pinning using multiple 0.8-mm flexible pins or Kirschner wires was developed ( Fig. 7.10 ). For this technique a cortical window is made using an awl in the ulnar base of the fifth metacarpal or 1 cm distal to the CMC joint for the radial three metacarpals. Two to four Kirschner wires can be used. The sharp tip can be removed and a slight bend placed wire to facilitate passage into the medullary canal. The wires are then advanced across the fracture site and seated into the subchondral bone of the metacarpal head. These pins can then be cut flush with the dorsal cortex to avoid extensor tendon irritation. Advantages include the ability to perform the procedure in a closed or limited open fashion and the ability to secure rotational control through three-point fixation.

Biomechanically, a single larger diameter (1.6 mm) pin has been demonstrated to be superior to three 0.8 mm wires in resisting cantilever stress though the rotational stability was not compared. Posner advised against IM fixation, in the belief that it does not control rotation and may produce secondary scarring in the extensor hood. In an effort to enhance rotational stability, eliminate external hardware and utilize minimally invasive techniques, IM unlocked and locked nails were introduced. Biomechanically the IM nails have been shown to be equivalent to crossed Kirschner wires. In a review of 55 cases, Mirza et al. achieved union and full range of motion in all cases; however, revision surgery for device removal was required in all cases. Clinical reports have demonstrated the ability of locked IM nails to maintain length, alignment, and rotation even in comminuted fractures secondary to gunshot wounds. Limitations of this technique include the need for implant removal, penetration of the MCP joint, extensor tendon irritation, and at times loss of reduction.

More recently, the use of IM screw fixation for metacarpal shaft fractures has gained popularity. The surgical technique is identical as described above for metacarpal neck fractures. From a biomechanical perspective, IM screw fixation has been shown to be superior to Kirschner wire fixation and inferior to plate and screw fixation with respect to ultimate tensile strength and four-point bending resistance. ^, Numerous studies, including a literature review of 169 fractures, have reported near full range of motion, 100% union rates, grip strength approaching 100% on the contralateral side, and excellent patient-reported outcomes using this technique. ^{, , , ,} When compared directly to IM Kirschner wires in two separate studies, IM screws were found to have a faster return to work and lessened period of immobilization but no difference with respect to the ultimate range of motion, grip strength, or DASH. ^, Limitations of the technique include increased cost relative to Kirschner wires and the potential for refracture or hardware deformation following subsequent trauma.

Open Reduction and Internal Fixation

Indications for open reduction of metacarpal shaft fractures vary widely. Melone noted that approximately 10% of phalangeal and metacarpal fractures were irreducible by closed manipulation or percutaneous pinning and thus required open reduction. Commonly accepted indications for open reduction include the following:

• • 1.

    Open fractures —particularly those with associated bone loss, soft tissue injury, or additional regional fractures.

  • 2.

    Multiple fractures —in such cases the stabilizing effect of the adjacent metacarpals may be lost. That said, not all patients with multiple metacarpal fractures, especially those with minimal displacement, require surgical intervention.

  • 3.

    Unstable fractures —especially those that cannot be satisfactorily held by closed or percutaneous techniques. Fractures of the border metacarpals tend to be more unstable and more difficult to control than fractures of the central metacarpals because of the lack of soft tissue support on both sides. Freeland and colleagues pointed out that there is a difference between rigid and stable fixation. Rigid fixation is usually unnecessary; however, fixation must be sufficiently stable to promote fracture union and early rehabilitation.

  • 4.

    Malalignment —rotational malalignment resulting in digital overlap is unacceptable and is characteristically seen in spiral and oblique fractures. When correction of a rotational deformity by closed techniques or percutaneous pinning is unsatisfactory, open reduction is often indicated.

Dorsal angulation, characteristic of transverse fractures, is better tolerated, particularly when the fracture involves the ring and small metacarpals or when the fracture is in the distal end of the shaft. Dorsal angulation has several undesirable effects that may lead to the decision for open reduction:

• • 1.

    The metacarpal head becomes prominent in the palm and may cause pain on grasping.

  • 2.

    There may be compensatory hyperextension at the MCP joint that results in a secondary intrinsic weakness and a pseudoclaw deformity in extension.

  • 3.

    Patients find the dorsal prominence esthetically displeasing.

In contrast to the phalanges, dorsal angulation does not seem to interfere with extensor tendon excursion. Flatt accepted up to 35 degrees angulation in the ring and little metacarpals, but not over 10 degrees in the second and third metacarpals. Smith and Peimer and Freeland et al. recommended open reduction if the angulation could not be corrected to under 10 degrees in the second and third metacarpals and under 20 degrees in the fourth and fifth metacarpals. Opgrande and Westphal believed that no angulation should be accepted in fractures of the second and third metacarpals.

Likewise, opinions vary as to the degree of acceptable shortening. Wolfe and Elliott mathematically demonstrated that with the same degree of angulation, there is more shortening in shaft fractures than metacarpal neck fractures. Butt and Bloem believed that shortening, even up to 1 cm, was well tolerated without functional impairment. Workman, however, attributed weakness of grip to metacarpal shortening in the belief that the relative decreased length of the musculotendinous unit decreased its efficiency. Eglseder et al. demonstrated an average of 3.1 mm of shortening in patients treated for isolated ring metacarpal fractures whether they underwent operative or nonoperative treatment and demonstrated no clinical differences between groups. FLOAT NOT FOUND

Techniques of open reduction and internal fixation ( eTable 7.1 )

eTABLE 7.1

Fracture Stabilization Techniques

Technique	Indications	Advantages	Disadvantages
Kirschner wires	Transverse	Available and versatile	Lacks rigidity
	Oblique	Easy to insert	May loosen
	Spiral	Minimal dissection	May distract fracture
	Longitudinal	Percutaneous insertion	Pin tract infection
			Requires external support
			Splint and therapy awkward
Intraosseous wires	Transverse fractures (phalanges)	Available	May cut out (especially osteopenic bone)
	Avulsion fractures	Low profile
	Supplemental fixation (butterfly fragment)	Relatively simple
Composite wiring	Transverse	More rigid than Kirschner wires	Pin or wire migration
	Oblique	Low profile	Secondary removal (sometimes)
	Spiral	Simple and available	Exposure may be significant
Intramedullary device	Transverse	No special equipment	Rotational instability
	Short oblique	Easy to insert	Rod migration
		No pin protrusion
		Minimal dissection
Interfragmentary fixation	Long oblique	Low profile	Special equipment
	Spiral	Rigid	Little margin for error
Plates and screws	Multiple fractures with soft tissue injury or bone loss	Rigid (stable) fixation	Exacting technique
	Markedly displaced shaft fracture (especially border metacarpals)	Restore or maintain length	Special equipment
	Articular and periarticular fractures		Extensive exposure
	Reconstruction for nonunion or malunion		May require removal
			Refracture after plate removal
			Bulky
External fixation	Restore length for comminution or bone loss	Preserves length	Pin tract infections
	Soft tissue injury or loss	Allows access to bone and soft tissue	Osteomyelitis
	Infection	Percutaneous insertion	Overdistraction: nonunion
	Nonunion	Direct manipulation of fracture avoided	Neurovascular injury
			Fractures through pin holes
			Loosening

Composite (tension band) wiring

A combination of Kirschner wires (0.035- or 0.045-inch diameter) and monofilament stainless steel wire (24- or 26-gauge) can also be used to further enhance construct stability ( Fig. 7.11 ). The monofilament stainless steel wire is inserted as a tension band through a small transverse drill hole in the distal fragment and crossed around the Kirschner wires at the bone interface proximally. Composite wiring provides additional stability and fracture compression and superior strength, stiffness, and approximation compared with crossed Kirschner wires alone. ^, Little, if any, additional dissection is necessary in the setting of open reduction. The technique is rigid enough to allow early motion. Greene et al. reported excellent mobility after fixation of 33 metacarpal fractures and no cases of reduction loss, nonunion, or tendon rupture. The technique is contraindicated when there is bone loss, comminution, or osteopenia. Care must be taken not to excessively tighten the wire, as this leads to wire breakage.

Cerclage and interosseous wiring.

Gropper and Bowen reported cerclage (circumferential) wiring with 24-gauge stainless steel wire for oblique and spiral metacarpal shaft fractures. Excellent results were reported in 21 fractures, but this technique has not gained popularity. Gingrass et al. achieved six excellent or good results in seven metacarpal fractures treated by double 26-gauge interosseous wires placed in a dorsal-volar direction. A single Kirschner wire was added if the fixation was unstable or bone loss was present (5 of 7 cases). Haas and Savage reported successful treatment of two oblique metacarpal shaft fractures with 0 nylon cerclage sutures in a patient with severe asthma and metal allergies. Interosseous wiring done without supplemental Kirschner wire fixation is generally not suitable for metacarpal shaft fractures inasmuch as wire loosening and subsequent loss of reduction are real possibilities; however, the technique can still be useful to augment other forms of fixation ( Fig. 7.12 ).

Interfragmentary compression screws

Interfragmentary compression screws provide rigid fixation and are primarily indicated for long oblique and spiral shaft fractures ( Fig. 7.13 ). To ensure success, the fracture length must be a minimum of twice (and ideally three times) the bone diameter. Technically, there is little margin for error. Interfragmentary compression is accomplished when a screw is passed through a gliding hole (nonthreaded and of wider diameter than the threads of the screw) into the far fragment (tapped to the same diameter as the screw threads) such that as the screw is tightened (lagged), the threads grip and draw the far fragment toward the near fragment until compression is achieved. Reduction of the fracture by manipulating it into alignment and holding the reduction with a specialized clamp must be achieved before attempting interfragmentary compression ( Fig. 7.14 ).

Ideally, longitudinal compressive (axial) forces are best counteracted by placing the screw 90 degrees to the bone’s long axis, and torsional stresses are best resisted by placing the screw 90 degrees relative to the plane of the fracture. To resist both axial and torsion loading, the screw should be placed in a plane bisecting the fracture plane and longitudinal axis. In large patients, at least two 2.7-mm screws are necessary, and in smaller individuals, three 2.4-mm or 2.0-mm screws are necessary. To avoid fragmentation, the screw hole should be a minimum of two screw diameters from the fracture margin. Successful outcomes have been reported by numerous surgeons with this technique. ^,

Interfragmentary screw fixation (2.7 mm) of a metacarpal fracture involves six sequential steps (see Fig. 7.14 ). There is little tolerance for error with this technique; it is critical that the screw engage the far cortex to lag and hence compress the fracture. If the screw is inserted through the near cortex and is misdirected such that it hits the endosteal surface of the far cortex, the fracture will splay apart and reduction will be lost. Hence any resistance to screw insertion should alert the surgeon to stop and redirect the screw so that reduction is not lost.

Plate fixation

In 1970 Simonetta listed indications for plate fixation of the metacarpal shaft: multiple fractures, especially those with soft tissue injury; isolated, unstable transverse fractures; malunions; and pseudarthrosis. Others ^, used plates to span defects when there was bone loss requiring grafting. In so doing, the plates provided enough stability so that early mobilization could be initiated, thus minimizing articular stiffness and trophic changes, especially in older patients. In several reports, plate and screw fixation of metacarpal shaft fractures have shown good to excellent results. Stern and colleagues reported complications in fractures treated with metacarpal plating. Complications included malunion, nonunion, and stiffness (articular and tendon adhesions). Complications were more frequent when there was associated bone loss, soft tissue injury, and open fractures.

Most implants are made of either stainless steel or titanium. Although titanium is more expensive, Lowka notes some advantages of titanium, including absence of corrosion or allergic reactions, ease of contouring, and a theoretical advantage of a modulus of elasticity that approaches bone. Great care must be taken when using titanium implants, as screws may break, especially when being removed, and plates can break if excessively contoured prior to application. Plate and screw fixation has been demonstrated to be biomechanically superior to both IM screw fixation as well as crossed Kirschner wires in several studies with respect to load to failure under bending loads. ^{, ,} One should keep in mind that the minimum strength for stable fixation in the clinical setting has never been determined; hence biomechanically inferior constructs may be perfectly suitable in some circumstances.

Currently, newer generation maxillofacial plating systems offer variable angle, precontoured, locking plates often with variable angled locking screw clusters. These designs allow for a greater number of locking screws to be placed over a shorter distance, thus minimizing the required dissection needed to achieve adequate secure internal fixation ( Fig. 7.15 ). ^, Screws are self-tapping and diameters range from 0.8 to 1.7 mm. Because the plates are low profile (approximately 1.0 mm), the periosteum can often be closed with less tendency for adhesion formation. Many systems also offer the benefit of in situ bending of the plates to enable correction of residual malalignment after plate application. While excess bending should be avoided to prevent fatigue failure of the metal, small angulation or rotational deformities can be corrected after placing provisional fixation. Fracture stabilization, although not rigid, is adequate to allow early mobilization with a low incidence of hardware failure.

External fixation

External fixation is indicated as temporary or definitive fixation for severe fractures when anatomic reconstitution of the skeleton is not feasible ( Fig. 7.16 ). Examples include highly comminuted open shaft fractures with or without bone loss; displaced, comminuted articular fractures; and fractures with injury or loss of soft tissue structures. In addition, external fixation can be used to stabilize septic nonunions when it is necessary to remove infected bone.

The advantages of external fixation were enumerated by Schuind et al. : “There is respect of bone biology.” Fracture fragments are not stripped of periosteal blood supply and further devascularized. External fixation does not cause the amount of osteopenia seen with more rigid systems such as plating; however, there is adequate stability to permit early mobilization. External fixators are adjustable, and a second reduction can be carried out if the initial reduction is unstable or has secondarily shifted. When there has been concomitant soft tissue injury, external fixation permits ready access to the wound for debridement as well as for reconstruction of tendons, nerves, and blood vessels. ^, Moreover, if there has been a delay in fixation such that metacarpal length is compromised, distraction lengthening of the metacarpal with external fixation followed by bone grafting can be performed.

Hastings has listed the complications and disadvantages of external fixation. These include pin tract infection, osteomyelitis, fracture through pinholes following removal, neurovascular injury during insertion, overdistraction with subsequent nonunion, loss of reduction, and interference with adjacent digits by the fixator. Also, pins may transfix extensor tendons or the dorsal apparatus and impair tendon excursion.

Combining the principles of external fixation with newer locking plate technology has led to the concept of using a bridge plate as an “internal ex-fix.” Certain nonreconstructible, often periarticular fractures can be managed with a spanning locking plate to maintain length, rely on ligamentotaxis, minimize soft tissue stripping, and maintain a similar respect for bone biology as an external fixator ( Fig. 7.17 ).

Bioabsorable Fixation

Although infrequently used in the United States, bioabsorbable implants are commonly used in some European locations. During fracture healing, the implants maintain fracture stabilization; however, over time they hydrolyze, resulting in stresses being transferred to the healing bone and thereby avoiding stress shielding. The implants are composed of either trimethylene carbonate, polyglycolic acid (PGA), polylactic acid (PLA), or polyparadioxanone and can be fabricated into pins, screws, rods, or plates. Biomechanical testing in cadaveric metacarpal and phalangeal bone shows that the implants provide fixation stability that is not statistical different from to metal implants. Because they resorb, a second procedure to remove the implant is avoided. The most common complication is a noninfectious inflammatory response that occurs 7 to 30 weeks following fracture fixation in approximately 5% to 25% of the cases.

Clinically, bioabsorbable IM rods were compared with metal implants for the fixation of metacarpal and phalangeal shaft fractures. There were no differences in outcome with respect to time to union, range of motion, and return to work. In a 1996 study, biodegradable pins (12 patients) were compared with Kirschner wires (11 patients) in the fixation of fractures, arthrodesis, and osteotomies in a prospective randomized study. No difference in time to union or complications was observed. Moreover, there were no inflammatory reactions in the biodegradable cohort. Given the lack of well-controlled recent studies or clear advantages, there is insufficient evidence to support the routine use of absorbable implants for metacarpal fracture fixation.

Avulsion Fractures of the Second and Third Metacarpal Bases

Isolated articular fractures of the base of the second and third metacarpals are rare because of the lack of motion in these joints: hence, there is no consensus regarding optimal treatment. These are usually the result of a fall on a palmar flexed wrist. Patients typically present with a palpable bony fragment and pain or weakness with resisted wrist extension. Avulsion fractures from the dorsal base of the index and/or middle metacarpals have been successfully managed both operatively ^, and nonoperatively. Justification for surgical reattachment includes restoration of the integrity of the extensor carpi radialis longus or brevis as a functional wrist extensor, prevention of EPL tendon rupture, reconstitution of the articular surface of the carpometacarpal joint, and elimination of a potentially irritating fragment of dorsal bone, which can often tent the overlying skin.

Fracture-Dislocations of the Small Finger Carpometacarpal Joint

Articular fractures of the hamate-metacarpal joint are common and typically the result of either a direct blow with a closed fist or high-energy trauma. These injuries are usually associated with proximal and dorsal subluxation of the metacarpal, though palmar dislocations are also reported. ^, Kerr was the first to point out the similarities between this injury and Bennett fracture, and this fracture has subsequently been referred to as a “baby Bennett fracture.” The hamate articulates with the ring and small metacarpals by two concave facets separated by a ridge. The base of the fifth metacarpal consists of a concave-convex facet that articulates with the hamate and a flat radial facet that articulates with the fourth metacarpal base. Dorsal and palmar intermetacarpal ligaments and an interosseous ligament stabilize the intermetacarpal joint. The injury results from a longitudinally directed force along the long axis of the fifth metacarpal. Usually a radial portion of the fifth metacarpal base remains articulated with the hamate and fourth CMC base, whereas the rest of the metacarpal is subluxated proximally and dorsally. The displacement is accentuated by the pull of the extensor carpi ulnaris. Lilling and Weinberg noted that the pull of the abductor digiti minimi as well as the oblique slope of the hamate also contributed to the instability of CMC fracture-dislocations of the small finger.

Because the extent of the injury is frequently missed on routine x-rays, Bora and Didizian have recommended an anteroposterior (AP) view with the forearm pronated 30 degrees from the fully supinated position. The diagnosis can also be made by CT or a Brewerton view. Kim et al. recently reported three-dimensional CT reformatted views to have a higher interobserver and intraobserver reliability than standard two-dimensional CT.

There is no consensus regarding optimal treatment of these fractures as evidenced by a recent systematic review. Options run the gamut from closed reduction and cast immobilization to spanning external fixation or open reduction and internal fixation. Successful closed reduction and cast immobilization have been reported by Lundeen and Shin and Hsu and Curtis. However, Bora and Didizian found that weakness of grip was the major functional disability resulting from inadequate reduction. Reduction of these fractures may be unstable, and I agree with several authors that have advocated simple closed reduction and percutaneous pin fixation of the fifth metacarpal to the fourth metacarpal or carpus to maintain reduction. ^,

Alternatively, open reduction and buttress plate application has been demonstrated in a case series of 11 patients to successfully reduce the fracture while maintaining the mobility of the ulnar-sided CMC joints by not securing the distal end of the plate to the metacarpal. Five patients (45%) required a second surgery for hardware removal.

Petrie and Lamb treated 14 fracture-dislocations of the fifth metacarpal-hamate joint by immediate, unrestricted motion and reviewed them at 4.5 years. Despite persistent metacarpal shortening, incongruity in the articular surface, and widening of the joint, only 1 patient had pain significant enough to affect work. They believed that the case for surgical treatment was not strong, inasmuch as arthrodesis of the joint could always be performed for persistent pain. On the other hand, Kjaer-Petersen et al. reported that regardless of the method of treatment (closed, percutaneous, or open), 19 of 50 (38%) patients had some symptoms at a median follow-up of 4.3 years. They believed that restoration of the articular surface should be the goal of treatment. Papaloizos et al. also advocated open reduction and noted that pain directly correlated with degenerative arthritis, which was attributed to nonanatomic reduction in several of their cases.

Cain et al. noted that fracture-dislocations of the fourth and fifth metacarpal joints, in association with comminuted dorsal hamate fractures or coronal fractures through the hamate, were particularly unstable and thus open reduction was uniformly necessary. When the hamate shear fracture is a single fragment, screw fixation of the hamate fragment to the body serves to treat both the fracture and the dislocation. ^,

Multiple Carpometacarpal Dislocations

Multiple CMC dislocations are high-energy injuries that nearly always require open reduction. ^, While the majority of these high-energy injuries are dorsally displaced, palmar dislocations and divergent dislocations are also well described. A high index of suspicion for associated carpal fractures, intercarpal ligament injuries, neurovascular injuries, and compartment syndrome should be suspected given the high-energy nature of these injuries. Lawlis and Gunther reported on 20 patients, 14 of whom had multiple CMC dislocations. Closed reduction was generally associated with recurrent dislocation or subluxation, and open reduction with Kirschner wire fixation was recommended for these injuries. At 6.5-year follow-up, 3 of the 4 patients with unsatisfactory results had closed treatment, and the fourth had a concomitant ulnar nerve palsy.

Schortinghuis and Klasen reported on open reduction of combined fourth and fifth CMC dislocations in 11 patients. They noted that placing a screw or plate across the fourth CMC led to spontaneous reduction of the fifth metacarpal. This permitted early range of motion and satisfactory results in all cases, though all had revision surgery for hardware removal.

Clendenin and Smith reported successful relief of symptomatic arthritis of the hamate-fifth metacarpal joint in seven patients treated by arthrodesis using an iliac crest bone graft. An alternative technique for painful fifth CMC arthritis is termed the “stabilized arthroplasty” and involves resection of the fifth metacarpal base and side-to-side fusion between the fourth and fifth metacarpal bases. Six of eight patients were evaluated at an average of 93 months following this procedure and demonstrated to have 10 to 20 degrees of fourth CMC mobility, excellent reduction of pain, but up to 70% loss of grip strength. Resection arthroplasty, ^, suspension arthroplasty using a slip of extensor carpi ulnaris (similar to thumb CMC arthroplasty), and silicone interposition arthroplasty have also been used for posttraumatic hamate-metacarpal arthritis.

Malunion

Metacarpal malunions may be classified as either articular or nonarticular. Nonarticular malunions may be angulatory, usually as a result of a malunited transverse shaft fracture; rotational, as a result of a spiral or oblique fracture; or shortened, as a result of a crush injury with bone loss. Following crushing injuries or open fractures, there may be shortening and associated soft tissue problems such as tendon adhesions, poor skin coverage, and neurologic deficit. In such cases, it may be most expeditious to perform an osteotomy and correct the soft tissue problem(s) simultaneously.

With modern techniques of plate and screw fixation or IM screws, union rates of metacarpal osteotomy have approached 100% and there has been a high degree of clinical satisfaction. ^, Lucas and Pfeiffer reviewed the AO experiences with osteotomies for 26 metacarpal and 10 phalangeal malunions. The osteotomy was done at the site of the deformity and fixation was accomplished with dorsal plates and screws. There were no nonunions, and 86% of the patients were satisfied. The failures were due to loss of motion or failure to fully correct the deformity. For more complex malunions, preliminary studies have shown patient-specific three-dimensional custom guides to be useful for precise correction.

Dorsal angulation

Metacarpal malunion following a transverse fracture results in dorsal angulation in the sagittal plane. Despite impressive radiographic malalignment, many nonarticular metacarpal malunions, especially those involving the ulnar digits, may be well tolerated and produce little functional deficits. Westbrook et al. found no correlation between the degree of dorsal angulation and patient reported outcomes in a series of 113 fractures; conversely, the authors found significantly better DASH scores in nonsurgically treated fifth metacarpal shaft fractures. At times, however, these malunions may cause weakness of grip or pain. Healing of second and third metacarpals with angulation is more likely to be bothersome, both cosmetically (pseudoclawing) and functionally (prominent metacarpal head in the palm that is painful when gripping). Correction can be accomplished through either an opening or closing wedge osteotomy. A closing wedge osteotomy is simpler, but critics have cited the disadvantage of further metacarpal shortening. However, Wolfe and Elliot demonstrated that the amount of dorsal bone removed for a 60-degree closing wedge osteotomy is more than compensated by restoration effected by the angular correction, resulting in a 7% gain in length ( Fig. 7.24 ). Preoperatively, the size of the wedge is calculated by using a template, and intraoperatively the volar periosteum is left intact to act as a hinge. I prefer fixation with a 2.4-mm dorsal plate or IM screw depending on the canal diameter. Supplemental cancellous bone graft harvested from the distal end of the radius is packed around the osteotomy. Union usually takes longer than after uncomplicated fracture fixation.

If the metacarpal is appreciably shortened due to bone loss, an opening wedge volar osteotomy can be performed through a dorsal approach with the expectation of several millimeters of lengthening ( Fig. 7.25 ). Cancellous bone graft should be placed in the volar defect. Stable fixation to allow early motion is accomplished with a dorsal plate. For cases with segmental metacarpal bone loss, a trapezoidal intercalary-type graft can be performed, but this is technically more difficult and may require considerable distraction.

Malrotation

Rotational malunion of a metacarpal can result in overlapping of the affected finger over an adjacent finger (scissoring). It usually results from a malunited spiral or oblique fracture. The cosmetic deformity is often marked and grip is impaired. Weckesser advocated a corrective osteotomy through the base and was able to correct up to 25 degrees in each direction for either metacarpal or phalangeal malunions. Fixation was accomplished with two transverse Kirschner pins through the distal fragment and into the adjacent metacarpal and was supplemented with a longitudinal pin extending across the osteotomy site ( Fig. 7.26 ). Menon reported full rotational correction of 11 of 12 osteotomies through the metacarpal base. Before the osteotomy, he inserted a Kirschner wire into the metacarpal perpendicular and distal to the osteotomy site, performed a transverse osteotomy, and then used the Kirschner wire as a handle to rotate the distal fragment into the desired position. Fixation was accomplished with crossed Kirschner wires. Manktelow and Mahoney used a rotational step-cut osteotomy to successfully correct metacarpal malrotation in 10 patients. Two transverse hemiosteotomies on opposite sides of the metacarpal diaphysis are cut and connected by a longitudinal dorsal osteotomy. A predetermined longitudinal strip of dorsal cortex is removed (1.3 mm of dorsal bone results in 1 cm of fingertip correction), and then a longitudinal fracture is created in the volar diaphyseal surface by compressing with a bone clamp. Tightening with interosseous wires approximates the gap. Pichora et al. and Jawa et al. advocated interfragmentary screw fixation of the diaphyseal split rather than interosseous wires (see Fig. 7.26 ).

I have been pleased with the results achieved when the osteotomy is performed through the metaphyseal base. After rotational correction, the osteotomy is transfixed with a longitudinal Kirschner pin. Correction is then assessed by observing the tenodesis effect of wrist flexion and extension, assessment of the plane of the fingernails, and checking that the fingertips point to the scaphoid tuberosity. If satisfied with the correction, I prefer fixation with a T-plate, L-plate, or minicondylar plate. Some small locking plate fixation systems allow for in situ bending to be performed after provisional fixation. This in situ bending allows additional precision for rotational alignment.

Osteomyelitis

Osteomyelitis following metacarpal fracture fixation or nonunion is uncommon and treatment must be individualized. In a review of osteomyelitis of the tubular bones of the hand, delay in treatment of more than 6 months or more than three procedures was associated with a very high amputation rate. For metacarpal shaft osteomyelitis, I prefer staged treatment using the Masquelet technique:

• • 1.

    Remove loose implants and generously debride bone and soft tissue. Gram stains and multiple cultures are sent for aerobic, anaerobic, and atypical organisms as warranted. Stabilization and length preservation can be provided with an IM pin and supplemented with a block of polymethylmethacrylate (with or without antibiotics added). This creates a biologically favorable induced membrane for insertion of a future bone graft. Appropriate systemic antibiotics are administered for at least 4 to 6 weeks.

  • 2.

    Typically around 6 weeks later, stage 2 surgery consists of removal of the antibiotic spacer, preservation of the induced membrane, placement of cancellous autograft, closure of the induced membrane over the graft, and fixation with plates and screws.