Tears may occur in ligaments (sprains), in muscles (strains), or in tendons. Tears may be graded as minimal (1st degree), moderate to severe (2nd degree), or complete (3rd degree). Third-degree sprains may result in joint instability and are differentiated from 2nd-degree sprains by stress testing. Third-degree tendon tears disrupt muscle function. Treatment of all tears includes analgesics, immobilization, and, for some 3rd-degree sprains and tendon tears, surgical repair.
Sprains commonly involve the acromioclavicular joint, proximal interphalangeal joint, knee (see Fractures, Dislocations, and Sprains: Knee Sprains and Meniscal Injuries), or ankle. Tendon tears commonly involve the knee extensor mechanism or Achilles tendon. Various muscles are commonly strained. Sprains, strains, and tendon tears cause pain, tenderness, and usually swelling. Second-degree sprains are very painful when stretched. Third-degree sprains often cause joint instability because ligaments that stabilize joints may be disrupted. In 3rd-degree tendon tears, the muscle cannot move the bone normally attached to it by the tendon; a tendon defect may be palpable.
Bedside stress testing involves passively opening the joint in a direction other than the normal range of motion (stressing) to check for joint instability; this test helps differentiate between 2nd- and 3rd-degree sprains. Because muscle spasm during acutely painful injuries may mask joint instability, the surrounding muscles are relaxed as much as possible, and examinations are begun gently, then repeated, with slightly more force each time. Findings are compared with those for the opposite, normal side. With 2nd-degree sprains, stress is painful, and joint opening is limited. With 3rd-degree sprains, stress is less painful because the ligament is completely torn and is not being stretched, and joint opening is less limited. If muscle spasm is severe, the examination should be repeated after injection of a local anesthetic, after use of systemic analgesia or sedation, or after a few days, when the spasm has subsided.
Treatment of all tears includes RICE (see Fractures, Dislocations, and Sprains: RICE) and, if necessary, analgesics. For 1st-degree tears, early mobilization is usually best. Mild 2nd-degree tears are often immobilized with a sling or splint for a few days. Severe 2nd-degree and some 3rd-degree sprains and tendon tears are immobilized for days or weeks, sometimes with a cast. Many 3rd-degree sprains and tendon tears require surgical repair.
Specific Sprains and Tendon Tears
Acromioclavicular joint sprains (separation)
The usual injury mechanism is a fall on the point of a shoulder or on an outstretched arm. Severe sprains tear the coracoclavicular ligament, displacing the clavicle upward from the acromion. Treatment is immobilization (eg, with a sling) and early mobility exercises. Some severe sprains are surgically repaired. This injury is often termed a shoulder separation.
Ulnar collateral ligament sprains (gamekeeper's thumb)
The ulnar collateral ligament connects the base of the thumb's proximal phalanx to the thumb's metacarpal bone on the ulnar aspect of the joint. The usual injury mechanism is lateral deviation of the thumb. Falling on the hand while holding a ski pole is a common mechanism. Diagnosis is by stress testing to check for radial deviation of the thumb; digital nerve block anesthesia is required. Treatment is immobilization with a thumb spica splint; if maximum possible radial deviation is > 20° more than that in the opposite thumb, surgical repair is necessary.
Quadriceps tendon injuries
The quadriceps tendon can be partially or completely disrupted. The elderly and people who have osteoarthritis or who are taking corticosteroids are especially at risk. The mechanism can seem minor, but includes forceful flexion of the knee, often while descending stairs. Patients with complete tears cannot stand, do a straight leg raise while lying on their back, or extend the knee while seated. An examiner can sometimes feel a rent in the tendon. X-rays may be normal or show a high-riding patella. Swelling in the area is diffuse and may be misinterpreted as a ligamentous knee joint injury with hemarthrosis. MRI confirms the diagnosis. Treatment is surgical repair as soon as possible, but long-term complications (eg, loss of motion and weakness) are common.
The most important ankle ligaments are the deltoid (the strong, medial ligament) and the anterior and posterior talofibular and calcaneofibular (lateral—see Fig. 7: Fractures, Dislocations, and Sprains: Ligaments of the ankle.). Ankle sprains are very common, typically resulting from turning the foot inward (inversion); inversion tears the lateral ligaments, usually beginning with the anterior talofibular ligament. Severe 2nd- and 3rd-degree sprains often cause chronic joint buckling and instability and predispose to additional sprains. Ankle sprains cause pain and swelling, which are usually maximal at the anterolateral ankle. Third-degree sprains often cause more diffuse pain and swelling (sometimes egg-shaped). Forcefully turning the foot outward (eversion) may tear the syndesmotic ligaments between the tibia and fibula proximal to the ankle (high ankle sprain). Occasionally, the deltoid ligament is sprained during eversion, often with simultaneous fracture of the fibular head.
Diagnosis is primarily clinical. The ankle anterior drawer test assesses stability of the anterior talofibular ligament, helping differentiate between 2nd- and 3rd-degree lateral sprains. For this test, patients sit or lie supine with the knee at least slightly flexed; one of the examiner's hands prevents forward movement of the anterior distal tibia while the other hand cups the heel, pulling it anteriorly. Avulsion fractures of the base of the 5th metatarsal and Achilles tendon injuries may be misdiagnosed as ankle sprains. High ankle sprains are considered when eversion is the mechanism and when eversion reproduces pain. Routine ankle x-rays are done to exclude significant fractures in patients with any of the following:
Complex ligamentous injuries to the ankle may require additional testing, such as MRI.
Most ankle sprains do well with minimal intervention and early immobilization. Splinting alleviates pain but does not appear to affect final outcome. First-degree sprains are treated with RICE and early weight bearing. Second-degree sprains are treated with RICE and immobilization of the ankle in a neutral position with a posterior splint, followed by mobilization; for mild sprains, mobilization can occur within a few days. Third-degree sprains may require casting or surgical repair. If clinical evaluation or determination of the extent of injury is impossible (eg, due to muscle spasm or pain), the injury may be immobilized and reexamined after a few days. Rarely MRI is used. High ankle sprains usually require a cast for several weeks.
Achilles tendon tears
The usual injury mechanism is ankle dorsiflexion, particularly if the tendon is taut. The calf is squeezed while the patient is prone (Thompson test); decreased passive ankle plantar flexion indicates a tear. Most tears are complete. Partial tears are often missed. Treatment of incomplete tears and some complete tears is a posterior ankle splint with the ankle in plantar flexion for 4 wk. Treatment of complete tears is usually immediate surgical repair. Spontaneous Achilles tendon rupture has been associated with the use of fluoroquinolone antibiotics.
Last full review/revision October 2007 by James R. Roberts, MD