Description of the condition
Ligaments are strong bands of tissue that link bones together at a joint. The ulnar collateral ligament (UCL) of the thumb is attached to the first metacarpophalangeal (MCP) joint, which is at the base of the thumb. The UCL is located on the medial (inner) side of the MCP joint, extending from the head of first metacarpal (the bone between the wrist and the thumb) and the base of the proximal phalanx (the base of the thumb). The function of the UCL is to prevent hyperabduction (extreme outward deviation) and forward displacement of the MCP joint of the thumb (Richard 1996).
UCL injuries can result from acute trauma, such as a fall on an outstretched hand or grasping an object during a fall. For example, if a skier falls with a pole in their hand during skiing, the handle of the pole may act as a fulcrum, applying force across the MCP joint and thereby putting the UCL under stress. Nowadays, UCL tears are often called 'skier's thumb' due to the high prevalence of UCL injury in skiers (Gerber 1981). UCL tears may also result from repetitive stress over a period of time as noted by Campbell who coined the term 'gamekeeper's thumb' (Campbell 1955). He noted that the gamekeeper's method of killing small animals such as rabbits put a particular stress on the MCP joint that, over time, injured the UCL. In clinical practice, repetitive injuries to the UCL are infrequently encountered as compared with acute injuries (Ritting 2010). In addition to repetitive stress or progressive incompetency, the term 'chronic injury' includes cases where initial diagnosis was missed and treatment delayed. UCL tears can be partial or complete and may involve an avulsion fracture, where a bone fragment is pulled away from the main bone. The UCL is usually torn at or near its insertion on the proximal phalanx (distal end).
As a result of these injuries, there is pain, swelling, bruising and difficulty in moving the thumb. Instability of the joint and weakness of pinch grip (between thumb and index finger) also occur. The weakness of pinch grip leads to marked limitation of basic activities of daily living such as opening jars or turning keys. If left untreated, the joint laxity (instability) may lead to degeneration (arthrosis/arthritis) of the thumb MCP joint. In some cases of complete UCL rupture, a painful nodular swelling results from the retraction of the torn part of the ruptured UCL, which becomes trapped under the adductor aponeurosis (a hand muscle that helps move the thumb). The adductor aponeurosis prevents the ruptured ends from making contact and thus healing of UCL on its own becomes impossible. This common type of complete rupture is known as a Stener lesion (Stener 1962).
The incidence of UCL injury has been reported to be between 2.2 to 4.4 per 1000 skiing days (Derkash 1987). A cohort study of the injury profile of alpine skiers found increased risk of thumb injury in males (Westin 2012). One study found that UCL injury accounted for approximately 86% of all the injuries of the thumb MCP (Moutet 1989). This injury has also been noted in other sports such as rugby, soccer, handball, basketball, volleyball, wrestling, martial arts and even after a handshake (Dey 2003; Moutet 1989; Rettig 2004). It has been suggested that people with less range of motion in the MCP joint (which in turn depends on the shape of the metacarpal head) are more susceptible to UCL injury (Richard 1996).
Diagnosis of UCL injury is based on patient history, clinical examination and other investigations. Other investigations include clinical stress testing under local anaesthesia, X-rays (routine or stress views), ultrasound, magnetic resonance imaging and arthrography. These injuries are frequently missed by inexperienced medical personnel (Musharafieh 1997).
Description of the intervention
UCL injuries can be treated surgically or non-surgically. Non-surgical or conservative options include plaster or splint immobilization (Sollerman 1991). Typically, the MCP joint is immobilized in the position of mild flexion and slight ulnar (inward) deviation at the MCP joint for four to six weeks. This positioning brings the torn ligament fragments closer, thus facilitating healing. A variety of plaster casts and splints are described in the literature. The standard thumb spica cast consists of layers of plaster of Paris or fibreglass molded over and enclosing the thumb, wrist and forearm. Other casts described in the literature include a modified thumb spica cast allowing removal and wrist motion (Primiano 1986), and a glove spica cast reported as enabling immediate return to activities or sports (Campbell 1992).
Unlike casts, splints are non-circumferential (and thus do not encircle the thumb or wrist) immobilizers that can accommodate swelling. The thumb spica splint consists of either a fabric enclosing a moderately pliable metal piece along the part that supports the thumb, or fiberglass/thermoplastic that can be cut and molded accordingly. Prefabricated and over-the-counter splints are also available. The splints may have adjustable straps to make them fit snugly around the thumb as well as the forearm. Immobilization is followed by physiotherapy, which includes joint mobilization followed by strengthening exercises.
Surgical options are 'direct repair', 'reconstruction' and 'arthrodesis' (joint fusion). Direct repair involves suturing the torn ligament ends together and/or fixing avulsed bone fragments such as with a pin or screw (Chuter 2009). Arthroscopic repair has been described as an alternative to open repair (Ryu 1995). One type of 'repair' of chronic UCL tears is the technique of condylar shaving (medial aspect of phalanx and metacarpal) (Haddock 2009).
Reconstruction often involves replacement with a graft, usually obtained from another part of the patient's hand (autograft), or using other nearby structures to stabilise the thumb (Fairhurst 2002). It is usually done for chronic lesions, where the ligament ends may not be in a good enough state for repair. It entails replacing the remnants of the torn UCL with a graft. Reconstruction may be a static (using a free tendon graft that has been extracted from elsewhere) or a dynamic tendon transfer (a tendon end, typically of the adductor pollicis, is relocated). The hand tendons commonly used as sources of grafts include the palmaris longus, flexor carpi radialis, flexor carpi ulnaris and the extensor pollicis brevis. A bone-soft tissue-bone graft has also been used to reconstruct UCLs (Wong 2009).The tendon grafts can be fixed by passing them through bone tunnels and securing them with a staple, button or screw; or by securing the graft to the bone surface using suture anchors (without needing to create bone tunnels). Some reconstructions may include suturing the MCP joint capsule (capsulorrhaphy) or, as mentioned above, advancement of the insertion of adductor pollicis.
Arthrodesis (joint fusion) involves removing the articular cartilage of both bones at the MCP joint and fixing the bone ends together with transarticular K-wires or screws or plates. This effectively removes the joint to form one length of bone. It is generally considered a salvage procedure, reserved for more severe injuries such as articular damage and cases of failed ligament repair or reconstruction (Baskies 2009; Fairhurst 2002).
After surgery, the MCP joint is placed in a cast or splint for four to six weeks. This is followed by physiotherapy, which includes joint mobilization followed by strengthening exercises.
How the intervention might work
The choice of treatment is influenced by a number of factors such as time of presentation (acute or chronic), associated bony avulsion (displaced or non-displaced), presence of Stener lesion, the site of ligament tear (the end or mid-substance) and the degree of thumb instability.
Conservative treatment is usually adopted in cases of acute injury where the ligament ends are in close proximity, such as in a partial tear. Cast or splint immobilization of the thumb MCP joint for a period of four to six weeks allows time for the torn ligament to rest and heal in an optimal position, and removes stresses resulting from movement during daily activities. Although this should facilitate healing of the UCL, while preventing further damage, casts are cumbersome, interfere with daily activities and usually have to be removed by attending a clinic. Additionally, the immobilized joint(s) can become stiff, which results in an increased need for physiotherapy after cast removal. By not enclosing the joint, splints and some types of cast allow for adjustments to accommodate hand swelling. Typically, splints are also lighter in weight and can be removed for daily activities of living such as bathing and skin care. Conversely, splints provide less protection than casts from pulls and jerks on the UCL during daily activities. Advocates of functional splinting argue, however, that controlled early active motion stimulates healing of ligaments (Michaud 2010). Similar considerations apply to cast or splint immobilization applied after surgery.
Surgery is necessary for restoring the UCL and joint function for UCL injuries such as Stener lesions, where the ruptured ends of the UCL need to be brought together again. The disadvantages of surgery include infection, iatrogenic injury, implant failure, neurovascular complications and joint stiffness. Compared with open repair, arthroscopic repair of the UCL is more technically demanding as the MCP joint is small and there is risk of damage to the articular cartilage from the instrumentation.
Reconstruction is a complex operation usually done for chronic lesions, where the ligament has degenerated over time and a direct repair may not hold or has not held. The disadvantages of reconstruction include the derangement of local functioning tissues (grafts) and complexity of procedures. Although reconstruction is usually reserved for chronic tears or failed primary repair, some authors have recommended repair over reconstruction even for chronic UCL tears (Ahmed 2012; Haddock 2009; Pai 2008).
Arthrodesis (joint fusion) is a salvage operation reserved for failed surgery or in the presence of joint pathology such as arthritis, which would otherwise make repair or reconstruction of the UCL futile. Arthrodesis achieves a pain-free, stable joint at the cost of lost mobility.
Why it is important to do this review
In one study, UCL injury accounted for approximately 86% of all the injuries of thumb MCP (Moutet 1989). It is an injury that is frequently missed by inexperienced healthcare personnel in the emergency department (Gerber 1981) and can be quite disabling for the patient if it is inadequately or improperly treated. There is also no consensus on the line of management, whether conservative or surgical, to be followed for either acute or chronic injury. With conservative management, there is uncertainty as to the best type of immobilization (plaster or splint) and optimum duration of immobilization. For acute UCL tears, some clinicians favor surgical management (Glickel 2005; Tsiouri 2009), especially if the tear is associated with high instability (as seen in a complete tear) (Derkash 1987; Posner 2012; Richard 1996; Weiland 1997). However, other clinicians favor conservative management (Abrahamsson 1990; Coonrad 1968; Landsman 1995; Pichora 1989).
In surgical management, reconstruction is usually reserved for chronic tears, but some prefer primary repair (Ahmed 2012; Pai 2008). There are different techniques of primary repair and reconstruction with uncertainty about which is the optimum technique for both methods. The optimal graft material for reconstruction of UCL is also unclear.
Our literature search revealed only a single systematic review on this topic (Samora 2013), with a search date of November 2011. Samora 2013 included a mixture of study designs including retrospective comparisons and case series, but excluded non-English language studies and studies with follow-up periods of less than two years. Our systematic review aims to clarify the best line of management for UCL injury based on the best available evidence from randomized controlled trials. This review will also help identify key areas where further research is required.