| The knee is a weight-bearing joint is supported by a system of ligaments, cartilage (medial and lateral menisci), muscles, and bone structure. A ligament connects a bone to a bone. A tendon attaches a muscle to a bone. A knee sprain is damage or tearing of ligaments or the joint capsule. A knee strain refers to damage or tearing of a muscle tendon unit associated with the knee joint.
In the knee, both sprains and strains are evaluated according to the amount of looseness (laxity or instability) and loss of function that they cause. A first-degree injury stretches the ligament or muscle tendon unit, but does not cause significant structural damage or weakness. First-degree sprains are characterized by minimal swelling (edema), localized pain and tenderness, and no marked instability. The individual with first-degree sprains may perform activities within the limits of pain tolerance without causing further damage to the knee. A second-degree injury partially disrupts and weakens the ligament or muscle tendon unit. Second-degree sprains are characterized by partial tears, moderately localized pain and tenderness, and mild instability. The injured structure must be protected from stress for a period of about 6 weeks in order to prevent further injury. A third-degree injury is one in which the ligament or muscle tendon unit is completely disrupted. Third-degree sprains exhibit complete tears, mild to pronounced edema, and clear instability. Third degree damage requires a long period of protection from stress and often surgical repair.
Sprains can occur in any or all of four knee ligaments. The lateral collateral ligament (LCL) is found on the outer side of each knee and attaches the thigh bone (femur) to the outside bone of the lower leg (fibula). The medial collateral ligament (MCL) is found on the inner side of each knee and attaches the femur to the shinbone (tibia). The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) are both found in the middle of the knee joint itself and also connect the femur to the tibia, helping to stabilize the knee joint. The MCL is the ligament most commonly injured, but damage to the ACL is the most common source of joint instability (Levy).
Sprains can occur in isolated or multiple ligaments. Sometimes other knee structures are injured in association with sprains, as in the famous "terrible triad" ("unhappy triad") of O'Donoghue, in which the ACL, MCL, and medial meniscus are all damaged. Strains are often associated with sprains and share the same risk factors and mechanisms of injury.
The knee is the most commonly injured joint in the body, with most injuries involving ligaments. Most sprains and strains result from sports activities, especially soccer, football, basketball, and skiing. Knee injuries also occur in automobile crashes.Risk: Less experienced and poorly conditioned individuals who engage in athletic activities are at greater risk for sports-type knee injuries, as are those who fail to warm up adequately. Knee injuries are more common in individuals who participate in sports such as soccer, basketball, and skiing. Incidence and Prevalence: Trauma to the knee is the second most common occupational accident in the US, where knee injuries in general affect over 3 million Americans annually (Levy). |
Source: Medical Disability Advisor
| History: The individual will most often relate a traumatic event. Sometimes the incident will have seemed insignificant at the time of occurrence. The mechanism of injury will provide valuable clues to the direction of impact and amount of force to the knee, as will information about the timing of onset of pain and swelling; immediate swelling is most often associated with acute ligament tears. Individuals may relate a history of pain in partial ligament tears, but pain is often absent in complete tears. Individuals also may complain of the knee "giving way." Many individuals with ACL sprain report a "popping" sound in the knee. Any history of prior knee injury and treatment will be noted. Physical exam: The examiner may touch (palpate) ligament and tendon insertion areas to elicit pain in any affected structures. Areas of localized swelling (edema) also may be felt on palpation. The joint itself may be filled with blood from the injury or with reactive synovial fluid (effusion). Pain along the course or attachment to bone (insertion) of a tendon usually indicates a strain, whereas such pain on palpation in a ligament area often indicates a sprain. Instability or excessive motion of the knee joint often is noted, although sometimes compensatory tightening of the surrounding muscles (physiologic splinting) may prevent detection of this loosening or instability. The individual may walk with a noticeable limp, as well as a "giving way" of the knee. Edema and bruising (ecchymosis) about the knee joint may be visible. The uninjured (contralateral) leg may be compared with the injured one to detect any relevant anatomical differences, such as the position of the kneecap (patella), and to determine a baseline level of normal laxity. Tests: Knee arthrometer measurements may be done to quantify the degree of laxity. Routine knee x-rays rule out fractures, dislocations, patella-femoral abnormalities, and loose bodies. Stress x-rays may be done. MRI may be ordered to examine the ligaments and articular surfaces. MRI is especially useful in detecting accompanying (concomitant) injury, as well as in examining the severity of ligament damage. MRI also can detect bone bruises (injury to the tissues covering the bone) that may not be evident on routine x-rays, an advantage that can be important in treating a patient with persistent pain. Draining fluid from the knee (joint aspiration) may be done to decrease pain and evaluate the fluid. Blood in the fluid (aspirant) indicates torn tissue or an intraarticular fracture; fat in the bloody fluid indicates a possible bone injury. Examination of the interior of the knee with an arthroscope (a device used to look inside of joints) may be necessary to confirm a diagnosis. |
Source: Medical Disability Advisor
| First-degree sprains and strains are treated conservatively with rest from the offending activity, with special consideration given to avoiding rotational or loading work to the knee. Ice, nonsteroidal anti-inflammatory drugs (NSAIDs), light knee wraps, and muscle strengthening exercises may be included in conservative treatment. Second-degree sprains or strains are often treated with braces that restrict but do not eliminate knee motion. It is critical to regain complete extension and flexion of the knee after injury while restricting rotation. Physical therapy modalities to decrease inflammation, strengthen muscles, and restore balance and agility are an integral part of the treatment.
Third-degree sprains may require surgical intervention for repair or reconstruction of the torn tissue. The decision to repair or reconstruct a ligament is based on the amount of instability, likelihood of increased injury without repair, number of ligaments injured, and any associated injuries.
Isolated MCL and LCL sprains usually are treated nonsurgically. If the ACL is injured, it is often treated surgically in younger and athletic individuals and non-operatively with bracing in older or sedentary individuals. (See Anterior Cruciate Ligament Repair)
Most cases of PCL injury require surgery. Surgery may involve sewing the ligament back together (end-to-end anastomosis) or anchoring it to bone (ligament-to-bone fixation). These procedures are often performed arthroscopically. Severe strains resulting in torn tendons usually require surgical repair. This surgery involves suturing of the tendon ends back together (tenoplasty) or anchoring the tendon to bone (tenodesis). Some ligaments cannot be repaired and the surgery involves creating an artificial ligament to replace the torn one.
Chronic instability due to rupture of tendons or ligaments is surgically repaired with procedures known as reconstruction or reconstruction with augmentation, which reinforces the unstable area with a fascia graft or transferred tendon. There are many such procedures, including the Slocum, Hughston, Clancy, and Muller procedures. |
Source: Medical Disability Advisor
| Isolated injuries to the collateral ligaments, even third-degree injuries, generally heal well with non-operative treatment. Third-degree collateral ligament sprains associated with other ligament or meniscus damage often require surgery, but generally will heal well. Recovery can be expected when first and second-degree sprains of ACL and PCL are treated with physical therapy and activity alteration. Third-degree sprains of ACL that are surgically repaired, with either primary repair or reconstruction with augmentation, require an extensive rehabilitation after surgery, but recovery can be expected. Surgery to treat third-degree injuries to PCL is rarely performed on middle-aged or older adults unless there is gross instability or associated injuries, especially of the meniscus. Individuals undergoing this surgery require an extensive rehabilitation afterwards, but recovery can be expected.
Full recovery from strains can be expected after physical therapy for first and second-degree injuries. Third-degree strains involving tendon rupture require surgery (tenoplasty, tenodesis, or a reconstruction with augmentation). Third-degree strains and sprains will require several months for full recovery. Return to limited activity may be expected early in treatment, with an interruption for surgery and eventual return to full activity. Knee braces are often used for all levels of sprains and strains, sometimes only in the early stages of recovery, and often for several months after surgery. Protective braces may be required after recovery to prevent re-injury. |
Source: Medical Disability Advisor
| Note on research and authorship The initial goal of the rehabilitation is to reduce pain and swelling. Controlling the pain and swelling associated with the acute phase of injury begins with PRICE (protection, rest, ice, compression, elevation) for the first 48 hours after injury or until swelling has stabilized (Braddom). Ice is not applied directly to the skin, and applications are limited to 20 minutes to prevent localized skin damage. Once the acute phase has subsided, current clinical practice supports the use of other modalities, heat or electrical stimulation, as means to promote pain control and allow for active rehabilitation.
For sprains and strains of the knee, a short period of immobilization and protection with a brace or semi-rigid support may be advised. The brace or supportive wrap should be discontinued when the individual exhibits full pain-free range of motion and pain-free ambulation.
Once the acute swelling and pain have subsided, individuals can be started on a rehabilitation program that will focus on functional training, with the intensity based upon the degree of soft tissue injury, in order to improve activities of daily living. Stretching exercises to promote full range of motion should be started as soon as possible. The treatment program will progress to strengthening and proprioceptive exercises as tolerated.
The final goal of therapy is to restore the individual's full pre-injury functional status. A home exercise program should be taught to complement supervised rehabilitation and to be continued as indicated, even after discharge from therapy.
Additional information may provide greater insight into the rehabilitation needs for managing this condition (Biundo). |
| FREQUENCY OF REHABILITATION VISITS | | Nonsurgical | |
| Physical Therapist | | Up to 16 visits within 8 weeks | | | | | | | | Surgical ‡ | |
| Physical Therapist | | Up to 24 visits within 12 weeks | |
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| ‡ Note on Surgical Guidelines: This table reflects the average rehabilitation needs. The degree of injury and surgical procedure can greatly impact on the duration of rehabilitation, and a longer period of rehabilitation may be required than that reflected in the table. |
| The table above represents a range of the usual acceptable number of visits for uncomplicated cases. It provides a framework based on the duration of tissue healing time and standard clinical practice. |
Source: Medical Disability Advisor
| Recurrent accumulations of fluid (effusions), osteoarthritis, buckling episodes (chronic instability) with loss of function, or any abnormal knee movement may complicate treatment and recovery. |
Source: Medical Disability Advisor
| During conservative treatment, walking, climbing, squatting, or kneeling during early treatment stages is restricted. This restriction may necessitate use of braces, crutches, canes, or wheelchairs. If crutches, canes, or wheelchairs are needed, relocation to an accessible area of the workplace may be required, along with additional safety precautions. Individuals will need frequent rest periods that allow for elevation of the lower leg. Company policy on medication usage should be reviewed to determine if pain medication use is compatible with job safety and function. Individuals whose injuries do not require surgical repair or reconstruction may nonetheless need time off from work to undergo extensive physical therapy to regain function.
During the recovery phase following surgery, avoidance of squatting, crawling, or kneeling for several months, along with use of a protective brace, may be necessary. Other activities to be avoided include jumping, twisting, lifting, pushing, or lunging. Avoidance of these activities is often facilitated by use of a protective brace to prevent re-injury. Additional time off for extensive physical therapy may be needed. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Has diagnosis been confirmed?
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Have conditions such as patella dislocation, patella-femoral pain syndrome, meniscal tears, tendinitis, gout, or rheumatoid arthritis been ruled out?
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If individual has continued pain or stiffness after conservative treatment, was an MRI done to rule out a missed meniscus injury or a fracture of any of the bones involved in the knee joint?
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If imaging results were equivocal, would diagnostic arthroscopy be appropriate?
Regarding treatment:
- Has individual been prescribed braces that restrict but do not eliminate knee motion?
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Has individual been enrolled in a comprehensive rehabilitation program that includes physical therapy modalities to decrease inflammation, strengthen muscles, and restore balance and agility as an integral part of the treatment?
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Is surgical intervention warranted and on what basis? Can procedure be performed arthroscopically?
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Has individual experienced any complications such as recurrent effusions, osteoarthritis, or chronic instability with loss of function?
Regarding prognosis:
- If injury was first and second-degree sprains of ACL and PCL, has individual been compliant with treatment of physical therapy and activity alteration regimen?
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If not, what can be done to increase compliance?
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If surgical repair or reconstructive surgery was performed, was individual enrolled in a comprehensive post-surgery rehabilitation program? Has individual been compliant with treatment plan?
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If individual was treated surgically, what were the extenuating circumstances?
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Is individual middle-aged or older?
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Does individual have any underlying condition such as fractures, associated injuries to the meniscus, dislocations of the patella, dislocation of the knee, or a total disruption of all support structures that may affect recovery?
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If symptoms persist despite treatment, does diagnosis need to be revisited?
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Have workplace accommodations been made to allow for surgery and resultant rehabilitation period?
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Would individual benefit from a performance brace? Additional physical therapy?
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Source: Medical Disability Advisor
| Biundo, J. J., R. W. Irwin, and E. Umpierre. "Sports and Other Soft Tissue Injuries, Tendinitis, Bursitis, and Occupation-Related Syndromes." Current Opinion in Rheumatology 13 2 (2001): 146-149. National Center for Biotechnology Information. National Library of Medicine. 22 Jan. 2009 <PMID: 11224739>.Braddom, Randolph L. Physical Medicine and Rehabilitation. 2nd ed. Philadelphia: W.B. Saunders, 2000. Levy, David. "Knee Injury, Soft Tissue." eMedicine. Eds. Eric Kardon, et al. 12 Dec. 2008. Medscape. 26 Nov. 2004 <http://emedicine.medscape.com/article/826792-overview>. |
Source: Medical Disability Advisor
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