Thumb and finger sprains involve injury to the ligaments of the joints. Ligaments are made of strong fibrous bands of tissue that attach and hold bones together across joints. The joints of the fingers and the thumb consist of the metacarpophalangeal (MP) joints and interphalangeal (IP) joints. Sprains occur from overstretching and tearing of these ligaments from an overload or violent motion to the joint, which range from minor injuries such as a jammed finger to more severe injuries such as a finger dislocation. These injuries are particularly common in sports. Minor finger or thumb sprains are associated with stretching of the ligaments, whereas moderate sprains involve partial tearing of ligaments. Complete tearing of ligaments occurs with more severe sprains which may cause instability of the injured joint. One of the more commonly torn ligaments of the thumb is the ulnar collateral ligament of the MP joint which is typically referred to as “skier’s thumb” since it is a very common skiing injury. When joint instability of the thumb or fingers results from inadequate treatment, chronic pain, deformities, and arthritis can eventually develop. On occasion, fractures of the bone may also occur as an avulsion injury where the ligament is pulled off with its attached bone together. However, even if the joint does not sustain a fracture, cartilage damage to the injured joint could occur particularly with a joint dislocation.
X-rays are usually taken with any jamming or dislocation injury to the thumb or fingers to assess for possible fractures and to assess alignment of the joints. Your hand doctor will examine your thumb or finger to determine stability of the joint and whether a ligament may be torn. If determination of joint stability or degree of ligament injury is uncertain, then an MRI of the injured joint may be necessary.
For the thumb, if the ligament is partially torn and the joint is stable, treatment typically consists of casting or splinting for a period of time followed by range of motion exercises. However, if the ulnar or radial collateral ligament to the thumb is completely torn resulting in an unstable joint, surgery is recommended for repair of the ligament. In particular, the ulnar collateral ligament of the thumb MP joint may not be capable of healing if left untreated since the ruptured ligament often gets trapped behind a tendon to the thumb. In cases of chronic or older injuries of the thumb MP joint ligaments, the joint may be painful with pinching, feel loose due to instability, and have decreased pinch strength. Surgery for these more chronic injuries may require a ligament reconstruction with a tendon graft to restore joint stability, or a joint fusion may be necessary if advanced arthritis is present. In the presence of arthritis, a corticosteroid injection and splinting may be of benefit before any eventual surgery.
Most finger sprains and ligament tears of the IP joints or knuckles are treated without surgery. Depending on the ligaments injured, typically buddy strapping or splinting of the finger is recommended with initiation of range of motion exercises. The IP joints of the fingers can be very unforgiving following injury and can develop significant stiffness. Protection of the finger from certain motions may be necessary depending on the type of injury. Your doctor will guide you on how to protect the finger, instruct you on the importance of your range of motion exercises, and explain the expectations of the injury. If dislocation of the finger joint occurs, it is important to know the direction of the injury and dislocation as the treatment can be very different. Most finger dislocations remain stable after the joint is put back into place and are treated without surgery. Range of motion exercises are typically initiated with use of buddy strapping of the fingers or with use of specialized splints that permit motion but block certain positions of motion. However, for some types of finger dislocations, the joint may need to be immobilized with a splint for an extended period of time to maintain joint stability and allow for healing of other associated injuries such as a tendon rupture. Evaluation in a timely manner is essential to help avoid excessive joint stiffness or inadequate treatment that can lead to secondary finger deformities.
When a more significant finger dislocation of the finger IP joint occurs, an associated fracture or break of the joint typically results as well. Depending on the size of the bone fragment, non-operative treatment may be recommended if the joint remains stable. However, if the joint is unstable, surgery may be necessary to stabilize the joint and to fix the joint surface. The joint may be fixed and stabilized using pins or screws. Sometimes external pins and distraction rubber bands may be necessary to hold the joint stable when the fractured bone is shattered at the joint. In cases of chronic or older finger fracture dislocations left untreated, surgery for reconstruction may be necessary to restore stability to the joint. Possible reconstruction options, depending of the injury pattern, include volar plate arthroplasty (advancement and reattachment of an important ligament into bone) or hemi-hamate bone grafting (transferring bone with cartilage from the hamate carpal bone in the wrist) to resurface the IP joint. These surgeries may improve functional use of the finger and reduce pain. Your specialist Dr. Katz will evaluate your injury and discuss the best options for treatment of your problem.