Rehabilitation of common knee injuries and conditions

INTRODUCTION — The knee has the largest articulating surface of any joint, and normal function is essential to weight bearing. Knee injuries are among the most common problems of adults and active youth and adolescents. Acute knee pain accounts for over 1 million emergency department visits and more than 1.9 million primary care outpatient visits annually in the United States alone [1-3]. Rehabilitation of knee injuries is essential to return to normal function.

This topic will discuss the important exercises used in the rehabilitation of common, uncomplicated knee injuries and conditions and the programs that use these exercises.

Guidance concerning the diagnosis of knee pain is provided separately. (See "Approach to the adult with knee pain likely of musculoskeletal origin" and "Approach to the adult with unspecified knee pain" and "Approach to acute knee pain and injury in children and skeletally immature adolescents".)

See separate topics for more detailed discussions of specific knee injuries and conditions. (See "Management of knee osteoarthritis" and "Patellofemoral pain" and "Meniscal injury of the knee" and "Medial (tibial) collateral ligament injury of the knee" and "Anterior cruciate ligament injury" and "Posterior cruciate ligament injury" and "Lateral collateral ligament injury and related posterolateral corner injuries of the knee" and "Iliotibial band syndrome" and "Quadriceps muscle and tendon injuries" and "Hamstring muscle and tendon injuries" and "Adductor muscle and tendon injury".)

ANATOMY AND BIOMECHANICS — The diagnosis of knee-related conditions and injuries, and the evaluation of knee function, require an understanding of the functional clinical anatomy and biomechanics of the knee. These are reviewed in detail separately. (See "Physical examination of the knee", section on 'Anatomy' and "Physical examination of the knee", section on 'Biomechanics'.)

PRINCIPLES OF REHABILITATION — Rehabilitation, or physical therapy, for knee-related injuries or conditions is performed in a progressive manner, each stage building on the prior one. Each phase of knee rehabilitation need not occur independently, but the goal is to move through each phase expeditiously until function is restored.

The early phase of rehabilitation is focused on reducing pain and optimizing functional knee motion [4]. Once pain is manageable and mobility is restored, attention can turn to improving strength, proprioception, and neuromuscular coordination. Ultimately, rehabilitation exercises should simulate the sport-specific or occupation-specific movements and activities that an athlete or worker must perform. The basic phases of knee rehabilitation, listed in the order they would be done, include the following:

●Reduce pain and protect the joint – Pain is a protective mechanism that helps to prevent further injury, primarily by limiting motion in the affected joint or limb. Cryotherapy, typically the controlled application of ice, has been shown to decrease pain [2]. Ice should be applied four to five times per day, approximately 20 minutes per application, during the acute phase of injury. Ice may be applied after a rehabilitation session to decrease swelling and pain.

Tendon-related pain can be reduced by a single resistance training session of isometric contractions. The effect of such training reduces tendon pain immediately and persists for at least 45 minutes [3]. This technique is useful for those undergoing rehabilitation for quadriceps and patellar tendon-associated injuries.

While some rehabilitation exercises may cause discomfort, the therapist should make adjustments in the type, performance, and intensity of an exercise to keep pain at a mild level (eg, no more than 3 on a 10-point scale). A steady increase in pain after a session or significant delayed onset pain indicates a need to reduce the intensity of therapy. A progressive reduction in pain with each therapy session suggests the current stage of therapy is being managed appropriately.

●Restore (or improve) mobility – If knee motion is diminished due to injury, the clinician must determine if the cause is pain, weakness, a mechanical obstruction due to injury, or the effects of prolonged immobilization.

After an injury or surgical procedure, knee mobility must be restored in order to perform activities of daily living and possibly movements required for sport. The degree of motion required of the knee to perform some basic activities of daily living and sport-related movements is found in the following table (table 1).

Prolonged immobilization can cause tightness of the hamstring and/or quadriceps muscle groups. Both muscle groups are important stabilizers of the knee, and appropriate flexibility and strength are essential for achieving full knee motion during healing. Manual testing to identify any hamstring or quadriceps strength and flexibility deficits should be performed early during rehabilitation.

To use a stationary bicycle or perform basic step exercises effectively, the knee must be able to achieve at least 90 degrees of flexion. Many other rehabilitation exercises may not be comfortable unless the injured knee can reach within 10 degrees of full extension. Strengthening of the quadriceps and hamstrings progresses more rapidly when knee mobility reaches these levels.

For hypermobile patients, the goal of most therapy programs is to regain full extension and normal flexion in the affected knee. The goal is not to regain the same degree of motion as the opposite uninjured knee when the uninjured joint exhibits hyperextension (genu recurvatum).

●Restore (or improve) proprioception and coordination – Exercises to restore proprioception and develop neuromuscular coordination are essential to the transition from a physical therapy exercise program to the functional movements necessary for normal activity and sport.

To assess proprioceptive function of the knee and coordination of the affected extremity, the patient can be asked to assume a single-leg stance in varying degrees of knee flexion, or to perform one-legged knee bends (for stronger patients). One important functional test is a step-down exercise during which the injured leg serves as the stance leg while the clinician observes the degree of dynamic genu valgum (medial collapse of the knee) that occurs when the patient descends a step. Similar movements can be used as exercises to develop proprioception and coordination.

●Restore high-level function – Progressive exercises that mimic the movements and skills required for the patient's sport or work form the core of the final stage of a well-designed rehabilitation program. The difficulty of such exercises should be increased very gradually, thereby allowing the neuromuscular system and soft tissues to adapt to the increasing demands being placed upon them.

●Perform functional assessment to determine readiness to return to play or work – It is important to make a formal assessment to determine whether a patient is ready to return to vigorous activity following a knee injury. As a general rule, before the patient resumes a demanding sport or heavy labor, the injured knee should demonstrate mobility, strength, proprioception, and overall function roughly equal to the unaffected knee. This assumes that the uninjured knee and lower extremity possess adequate strength and function. The ability to perform the tasks entailed in the sport or work to which the patient will return without pain, swelling, or instability suggests that rehabilitation has been adequate.

In addition, several functional tests have been used to determine if a patient is able to return to full activity or sport. As an example, single-leg hop tests have been used to assess patients following reconstruction of the anterior cruciate ligament (ACL) and rehabilitation. Although multiple versions exist, four hop tests are used most often: (1) single-limb single hop for distance, (2) single-limb triple crossover hop for distance, (3) single-limb triple hop for distance, and (4) the single-limb six-minute timed hop.

REHABILITATION PROGRAMS FOR SPECIFIC INJURIES

Medial collateral ligament of the knee — Injuries of the medial collateral ligament (MCL) of the knee occur frequently in athletes, particularly those involved in sports that require sudden changes in direction and speed, and in patients struck on the outside of the knee (figure 1 and figure 2). Most heal well with conservative treatment. The risk factors, clinical presentation, diagnosis, and management of MCL injuries are discussed separately. (See "Medial (tibial) collateral ligament injury of the knee".)

Understanding the severity of the MCL injury is important when prescribing a rehabilitation program. MCL sprains can occur as an isolated injury or in association with other structural damage (posterior joint capsule, meniscus, or cruciate ligament injuries). Isolated MCL sprains can be classified clinically using the valgus stress test for joint laxity. The maneuver is performed with the knee at 30 degrees of flexion and again with the knee in full extension. Examination methods for determining the severity of MCL injury are detailed separately. (See "Medial (tibial) collateral ligament injury of the knee", section on 'Physical examination'.)

The severity of an MCL sprain helps to determine appropriate treatment, with grades 1 and 2 routinely treated with rehabilitation alone. Many isolated grade 3 sprains are also treated solely with rehabilitation. However, it is important to distinguish grade 3 sprains and sprains associated with additional knee injuries, as treatment protocols are often more complex and rehabilitation alone may not be sufficient treatment [5-7].

Even with concomitant anterior cruciate ligament (ACL) disruption, the MCL injury can often be treated safely with conservative rehabilitation exercises while awaiting definitive treatment of the ACL injury. Other associated injuries that would alter the treatment plan for an MCL injury, and possibly the approach to rehabilitation, include bony avulsion of the MCL attachment, tibial plateau fracture, and the presence of osteochondral fragments.

A standard rehabilitation program for MCL injuries is outlined below, along with links to images and video clips demonstrating the exercises. A step-by-step description of the program is provided in the accompanying table (table 2).

●Acute phase

Goals – Reduce pain; maintain mobility and minimize atrophy

Exercises:

•Isometric quadriceps contractions

•Straight leg raise (picture 1)

●Subacute phase: Early

Goals – Improve mobility and strength

Exercises:

•Hamstring, quadriceps, and hip flexor stretches, if mobility restrictions are present:

-Hamstring stretch (picture 2 and picture 3)

-Quadriceps stretch (movie 1 and movie 2)

-Hip flexor stretch (figure 3 and movie 3)

•Begin non-weight bearing, light resistance exercises listed; exercises should avoid putting a varus or valgus stress on the leg:

-Heel slides (picture 4)

-Straight leg raise (picture 1)

-Short-arc quadriceps extension (picture 5)

-Hamstring curl (picture 6)

-Hip abduction (picture 7)

-Hip extension (picture 7)

•May increase endurance activities (eg, stationary bicycle with light resistance 10 to 30 minutes)

●Subacute phase: Progressive

Exercises:

•Continue exercise program above with greater resistance

•Begin resistance exercises below:

-Leg press (picture 8)

-Hamstring curl (picture 6)

-Knee (quadriceps) extension (picture 9)

-Partial two-leg squats – Knee flexion to 45 degrees (picture 10)

●Functional phase

Goals – Improve mobility, strength, and balance

Exercises:

•Core stability exercises (picture 11)

•Progression of strength and endurance exercises from earlier phases, may include:

-Single-leg half squats on affected leg (picture 12 and movie 4)

-Side step-ups on affected leg (movie 5)

-Walking lunge (movie 6)

-Stair walks

•Graded balance/proprioception exercises program as appropriate for goals

●Sport-specific phase

Goal – Prepare for return to full sport/activity

Exercises:

•Continue but reduce total amount of strength and endurance exercises from functional phase

•Add lunges (picture 13 and picture 14 and movie 7 and movie 6 and movie 8), skipping, jumping, and sport-specific movements; gradually increase intensity and duration

•Begin dynamic functional drills, such as jumping off a small box and landing softly with stable knees (eg, without notable knee varus or valgus angulation) (picture 15)

●Maintenance phase

•Continue lower extremity strengthening program along with proprioception program. Complete recovery from MCL strain can take up to one year.

Lateral collateral ligament of the knee — Isolated injury of the lateral collateral ligament (LCL) is uncommon (figure 1 and figure 2). Significant LCL injuries such as grade 3 tears are frequently associated with injury to either one of the cruciate ligaments or the posterolateral complex (PLC), sometimes referred to as the posterolateral corner. The PLC consists of the popliteus tendon, the popliteofibular ligament, the arcuate ligament, and the posterolateral joint capsule. Patients with suspected concomitant ACL, posterior cruciate ligament (PCL), or PLC damage should be evaluated for possible surgical intervention and are generally not treated with physical therapy. (See "Anterior cruciate ligament injury" and "Posterior cruciate ligament injury" and "Lateral collateral ligament injury and related posterolateral corner injuries of the knee".)

The integrity of the LCL (endpoint stability) should be examined with the knee in both 15 to 30 degrees of flexion and at full extension. Isolated grade 1 or 2 LCL injuries are amenable to conservative treatment with physical therapy using programs designed primarily for MCL strains. Examination of the LCL is discussed separately. (See "Lateral collateral ligament injury and related posterolateral corner injuries of the knee", section on 'Clinical presentation and examination'.)

Patellofemoral pain — Patellofemoral pain (PFP) is defined as anterior knee pain involving the patella and retinaculum. The clinician must exclude other intra-articular and peripatellar pathology before ascribing symptoms to PFP. The underlying causes of PFP remain a source of debate and are likely multifactorial. The condition is relatively common among running athletes. (See "Patellofemoral pain".)

Rehabilitation programs that include open- and closed-chain exercises, multimodal physiotherapy, foot orthoses, and patellar taping have all been shown to reduce PFP-related symptoms at short-term (less than one year) follow-up [8-13]. Long-term improvements (greater than one year) have proven more difficult to sustain [9]. According to a randomized trial involving several hundred military trainees, an exercise program consisting of several simple strength and mobility exercises can prevent the development of anterior knee pain [14].

The focus of a general rehabilitation program for PFP is on strengthening the quadriceps muscles, posterior-lateral hip muscles (hip extenders and external rotators), and the trunk. As PFP is likely multifactorial, clinicians should pay close attention to identifying their patient's particular strength and mobility deficits. The rehabilitation protocol should be tailored to address the problems identified.

A standard rehabilitation program for PFP is outlined below, along with links to images and video clips demonstrating the exercises. A step-by-step description of the program is provided in the accompanying table (table 3).

●Acute phase

Goals – Reduce pain; prevent muscle atrophy

Exercises:

•Isometric quadriceps contractions with knee at 60 degrees of flexion

•Heel slides (picture 4)

•Standing hip abduction and adduction

●Subacute phase: Early

Goals – Improve mobility and strength

Exercises:

•Hamstring stretch (supine) with knee in full extension while hip is at 90 degrees of flexion (picture 3)

•Begin short-arc quadriceps extension exercises (picture 5)

•May perform hip external rotation (clamshell) exercises as tolerated (movie 9 and movie 10)

●Subacute phase: Progressive

Exercises:

•Quarter squats – Knee flexion no greater than 45 degrees (picture 10 and movie 11 and movie 12)

•Exercises with resistance bands:

-Hip abduction, standing (figure 4 and movie 13)

-Hip extension to 45 degrees, standing (movie 14)

-Hip internal rotation, seated

-Hip external rotation, seated

●Functional phase

Goals – Improve mobility, strength, and balance

Exercises:

•Begin stair climbing and lunges (movie 7 and movie 6 and movie 8)

•Half squats – Knee flexion no greater than 75 degrees (picture 10 and movie 11 and movie 12)

•Begin balance/proprioception exercises:

-Plank (picture 16)

-Single-leg half squats on affected leg (picture 12 and movie 4)

-Side step-ups on affected leg (movie 5)

-Single-leg stand (movie 15)

●Sport-specific phase

Goal – Prepare for return to full sport/activity

Exercises:

•Continue basic strength program (eg, squat to 90 degrees knee flexion, single-leg squat, rear-leg-elevated squat (picture 17), planks (picture 11))

•Add skipping, jumping, and sport-specific movements; gradually increase intensity and duration

●Maintenance phase

•Continue lower extremity and trunk strengthening program to maintain strength gains

Quadriceps and patellar tendinopathy ("jumper's knee") — Repetitive running or jumping activities can produce pain at the origin of the patellar tendon. Formerly known as patellar tendinitis, this condition (also called "jumper's knee") is in fact an overuse tendinopathy rather than an inflammatory condition. Similar problems can develop at the quadriceps tendon, although this is much less common. (See "Quadriceps muscle and tendon injuries", section on 'Quadriceps tendinopathy'.)

The initial phase of rehabilitation for patellar or quadriceps tendinopathy is focused on reducing pain, which requires reducing the stresses placed on the patellar tendon. Throughout rehabilitation, it is important to monitor tendon loads to optimize recovery. Early in the rehabilitation program, activities that place a high load on the tendon should be avoided, although it is also important to avoid resting the injured lower extremity completely.

Sustained isometric contractions allow muscles and tendons to be worked while reducing pain [15-18]. A major advantage of isometric exercises is that they can be performed by athletes with mild tendinopathy who continue to play their sport, while many other interventions require that they cease activity. Sets of isometric quadriceps contractions performed at approximately 70 percent of maximum effort and held for 45 to 60 seconds appear to be effective and can be performed several times daily, including before games or training. Several small randomized trials report that such isometric exercises led to sustained reductions in pain [3,16-18].

Two types of exercise, eccentric (picture 18) and heavy slow resistance (HSR), can be used for the strengthening phase of patellar tendon rehabilitation. Eccentric exercise involves the muscles lengthening under a load (eg, decline squat). HSR involves performing an exercise through a functional range of motion using heavy resistance (eg, no more than 8 to 10 repetitions can be performed before failure). The rehabilitation program below incorporates elements of both approaches. Evidence supporting either approach is limited, but the results of a few small randomized trials support each [19-22]. In a small randomized trial comparing eccentric exercise-based rehabilitation with a program using progressive tendon-loading resistance exercises, patients using the latter approach made greater progress [23].

During rehabilitation, a single-leg decline squat can be used to monitor symptoms and to assess readiness for return to activity. The decline squat provides information about tendon response to loading. As the tendon heals and pain diminishes, the patient will be able to squat lower with less discomfort. Consistent or improving pain scores suggest that the tendon is coping adequately with loads [24]. The Victorian Institute of Sport Assessment score, a brief questionnaire about knee symptoms, can also be used to assess progress during rehabilitation [25].

Published evidence about specific rehabilitation protocols for quadriceps tendinopathy is limited. However, general concepts of tendinopathy treatment, specifically those drawn from the treatment of patellar tendinopathy, provide a useful guide for management [26]. Expert opinion supports stretching and isometric strengthening exercises early in the course of treatment [27]. Controlled, progressive, heavy-load exercise, including eccentric strengthening, is the cornerstone of treatment and can be initiated when pain diminishes.

A sample rehabilitation protocol with details about exercises and indications for progression is provided in the accompanying table (table 4). A simple outline of the program with links to images and video clips demonstrating the exercises is provided below.

●Acute phase

Goals – Reduce pain; prevent muscle atrophy

Exercises:

•Isometric quadriceps contraction:

With knee in slight flexion, voluntarily contract muscle using approximately 70 percent of maximum effort; hold for 45 to 60 seconds; perform four sets. Exercise can be performed multiple times per day and before games or training.

If approach above causes undue discomfort, contractions can be performed with both quadriceps, for shorter duration (eg, 15 seconds), or for fewer sets.

●Subacute phase: Early

Goals – Improve mobility and strength

Exercises:

•Eccentric exercises with decline squats (picture 18). Gradually, the angle of decline is increased.

●Subacute phase: Progressive

•Continue eccentric squat program. Gradual progression to 60 degrees knee flexion, then to single-leg squat, and finally to single-leg squat with added weight.

•Can begin tendon-loading exercises in progressive fashion. May start with isometric holds (eg, wall sit) and progress to dynamic exercises (eg, leg press).

•May add quadriceps (knee) extension (picture 9) and hamstring curl exercises (picture 6) provided they do not cause pain.

●Functional phase

•Continue eccentric squat program

•Continue quadriceps extensions and hamstring curls

•Introduce graded balance/proprioception exercises program as appropriate for goals

•Other exercises used by some clinicians during the functional phase include:

-Step down (picture 19)

-Reverse Nordic lower (picture 20)

-Overhead reverse lunge (picture 13)

-Drop squat (picture 21)

-Drop jumps (picture 15)

●Sport-specific phase

•Functional strength exercises during this phase must address high-load tendon capacity as well as kinetic chain deficits and faulty movement patterns

•Once these problems have been corrected, the athlete begins to perform more challenging movements such as skipping, jumping, and hopping

•Progress to agility tasks, rapid direction changes, sprinting, bounding, and sport-specific movements

It is important to quantify these tasks and use a high-low-medium-load day approach in early reintroduction of high-load activities.

●Maintenance

•Continue eccentric exercises to maintain strength

Quadriceps muscle injury — Muscle strains involving one or more of the quadriceps (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius (figure 5)) are common sports-related injuries. The most common mechanism involves a sudden, forceful eccentric contraction performed during a sudden change in direction while sprinting (ie, "cutting"), or when landing from a jump or running downhill. Injuries may also occur from a direct blow or from overuse. (See "Quadriceps muscle and tendon injuries".)

Following injury, quadriceps muscles quickly develop some degree of weakness without intervention. Therefore, a progressive rehabilitation program should begin as early as possible after injury.

A standard rehabilitation program for quadriceps muscle injury is identical that used for patellar and quadriceps tendon injury and is described above. (See 'Quadriceps and patellar tendinopathy ("jumper's knee")' above.)

Meniscal injury (nonoperative and/or postoperative) — Meniscal injuries may occur from an acute traumatic event or a chronic degenerative process, as an isolated condition or in combination with other knee injuries, such as an ACL tear (figure 6 and figure 7). Acute meniscal tears can occur in any age group, but chronic, degenerative meniscal injury usually occurs in older patients. Initial treatment is similar for acute meniscal injury, degenerative tears, and postoperative rehabilitation after meniscectomy. Meniscal tears that cause symptomatic locking or giving way of the knee should be referred to a surgeon. If such symptoms are absent, an initial trial of rehabilitation is reasonable [28]. Rehabilitation is especially appropriate for those suffering degenerative tears [29]. The rehabilitation program provided below is designed for patients with an isolated meniscal injury. (See "Meniscal injury of the knee".)

The details of a rehabilitation program for meniscal injury are determined by the patient's goals and expectations, coexisting knee pathology, and the type of meniscal tear. For all meniscal injuries, the initial goal is maximizing knee mobility. Pain and swelling can limit joint motion, so they should be treated as necessary with standard measures, including ice, mild compression, elevation, and over-the-counter analgesics. Prolonged knee immobilization should be avoided as it can lead to muscular atrophy and ultimately delay functional recovery. Progressive weight bearing is allowed, but excessive shear forces on the meniscus should be avoided as they can disrupt healing. Aquatic therapy allows for controlled weight bearing and is a useful technique for some patients (in the postoperative setting, aquatic therapy must be delayed until wound healing is adequate) [30-32]. Balance tests are a valuable tool to assess both strength and proprioception in patients with a meniscus injury.

A standard rehabilitation program for conservatively treated meniscus injury is outlined below. A step-by-step description of the program is provided in the accompanying table (table 5). For a postoperative program, progress would be slower and the acute phase with limited exercises might extend longer until most swelling resolves.

●Acute phase

Goals – Reduce pain; prevent muscle atrophy

Exercises:

•Isometric quadriceps and hamstring contractions with knee at approximately 45 degrees flexion

●Subacute phase: Early

Goals – Improve mobility and strength

Exercises:

•Heel slides (picture 4).

•Knee extension and flexion mobility exercises to obtain full range of motion.

•Begin stationary bicycle for knee mobility and strengthening and general endurance; be certain seat is high enough to avoid excessive knee flexion (should not exceed 90 degrees); initial resistance is light and gradually progresses to moderate.

●Subacute phase: Progressive

Exercises:

•Single-leg squat with knee flexion no greater than 45 degrees (picture 12 and movie 16 and movie 4)

•Step-up (movie 5) – As patient strength increases, step-up exercises may be performed while holding weight

•Hamstring bridge (picture 22) or hamstring curl (picture 6)

•Single-leg press (picture 8)

•Single-leg knee (quadriceps) extension (picture 9)

•Skating exercise

•Continue stationary cycling for endurance

●Functional phase

•Begin stair climbing and lunges (movie 7 and movie 6 and movie 8)

•Half squats – Knee flexion no greater than 75 degrees (picture 10 and movie 11 and movie 12)

•Core stability and balance exercises:

-Plank and bird-dog (picture 11)

-Single-leg half squats on affected leg (picture 12 and movie 4)

-Side step-ups on affected leg (movie 5)

-Single-leg stand (movie 15)

•Introduce graded balance/proprioception exercises program as appropriate for goals

•Continue stationary cycling for endurance

●Sport-specific phase

•Functional strength exercises during this phase must address high-load tendon capacity as well as kinetic chain deficits and faulty movement patterns

•Once these problems have been corrected, the athlete begins to perform more challenging movements such as skipping, jumping, and hopping

•Progress to agility tasks, rapid direction changes, sprinting, bounding, and sport-specific movements

It is important to quantify these tasks and use a high-low-medium-load day approach in early reintroduction of high-load activities.

●Maintenance

•Continue exercises to maintain good quadriceps and hip muscle strength

•Continue biking or stationary cycling for endurance and quadriceps strength

Iliotibial band syndrome — The iliotibial band (ITB) is a fibrous band that runs longitudinally along the lateral aspect of the thigh from its origin at the iliac crest to the proximal tibia (figure 8). The ITB is thought to assist with knee extension when the knee is near terminal extension, and with knee flexion once the knee is flexed beyond 30 degrees (figure 9). The ITB also provides lateral knee stability. ITB syndrome is an overuse injury of the lateral knee that occurs primarily in runners but can occur in cyclists and other athletes. The factors that predispose some athletes to ITB syndrome remain a source of debate. (See "Iliotibial band syndrome".)

Rehabilitation programs for ITB syndrome focus on identifying and correcting strength deficits and discrepancies and mobility deficits. Common problems addressed by such programs include strengthening weak hip abductor muscles and improving the mobility of the ITB itself and its related muscle groups (eg, gluteus medius, gluteus maximus, vastus, lateralis, tensor fascia lata). Rehabilitation of ITB syndrome is discussed in greater detail separately. (See "Iliotibial band syndrome", section on 'Treatment'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues in muscle and tendon injury diagnosis and management" and "Society guideline links: Muscle and tendon injuries of the lower extremity (excluding Achilles)" and "Society guideline links: Knee pain" and "Society guideline links: Meniscal injury".)

SUMMARY AND RECOMMENDATIONS

●Conditions amenable to rehabilitation – Knee pain and injuries are among the most common reasons for emergency department and primary care outpatient visits. Many common causes of knee pain improve with appropriate physical therapy programs. Such causes include low-grade sprains of the collateral ligaments, patellofemoral pain (PFP) syndrome, osteoarthritis flares, quadriceps and patellar tendinopathy, uncomplicated meniscal injury, and others.

●Rehabilitation principles – Physical therapy for knee-related conditions is performed in a progressive manner, each stage building on the prior one. The early phase of rehabilitation is focused on reducing pain and optimizing mobility. Once pain is manageable and mobility is restored, attention turns to improving strength, proprioception, and neuromuscular coordination. In the final stage, the emphasis is on regaining the ability to perform sport-specific or occupation-specific movements and activities. (See 'Principles of rehabilitation' above.)

●Links to specific programs – Specific rehabilitation programs for common, uncomplicated injuries are provided in the text and accompanying tables:

•Medial collateral ligament (MCL) injury (see 'Medial collateral ligament of the knee' above)

•Lateral collateral ligament (LCL) injury (see 'Lateral collateral ligament of the knee' above)

•PFP syndrome (see 'Patellofemoral pain' above)

•Quadriceps and patellar tendinopathy (see 'Quadriceps and patellar tendinopathy ("jumper's knee")' above)

•Meniscal injury (see 'Meniscal injury (nonoperative and/or postoperative)' above)

•Iliotibial band (ITB) syndrome (see "Iliotibial band syndrome", section on 'Treatment')