Musculoskeletal: The Lower Extremity and Gait

Most of what a physical therapist does for the lower extremity comes down to one question: can this patient bear weight and walk safely, and if not, why not? The NPTE tests that question through hip and knee arthroplasty precautions, ligament and meniscus injuries, ankle sprains, the gait cycle and its deviations, and weight bearing orders after fracture. This chapter ties the tissue, the protocol and the gait pattern together so you can reason from findings to the safest correct answer.

Section 1The hip

Hip osteoarthritis

The hip is a deep ball and socket joint whose stability comes mainly from bone, the labrum and strong capsular ligaments (iliofemoral, pubofemoral and ischiofemoral, all tightening in extension). Osteoarthritis of the hip is a disease of the whole joint: cartilage loss, subchondral sclerosis, osteophytes and capsular thickening. The classic presentation is groin or anterior thigh pain (sometimes referred to the knee), morning stiffness lasting less than an hour, pain with weight bearing and a capsular pattern of loss: internal rotation and flexion most, then abduction, with extension also limited. The hip clinical practice guideline lists features that support the diagnosis in adults over 50: moderate anterior or lateral hip pain with weight bearing, morning stiffness under an hour, and hip internal rotation and flexion each limited by more than 15 degrees compared with the other side.

Evidence based treatment includes patient education and weight management, manual therapy (mobilization and manipulation) for short term pain relief and motion, flexibility and strengthening (especially hip abductors, extensors and quadriceps), functional and balance training and an assistive device when needed. A cane is held in the hand opposite the painful hip: it moves with the involved leg and reduces the abductor force needed on the stance side, lowering joint reaction force. Carrying a load in the hand on the same side as the painful hip also reduces abductor demand, whereas carrying it on the opposite side increases it.

Femoroacetabular impingement and labral tears

Femoroacetabular impingement (FAI) is abnormal contact between the femoral head neck junction and the acetabular rim. A cam lesion is an aspherical bump at the femoral head neck junction, more common in young athletic men; it is jammed into the acetabulum in flexion and internal rotation, shearing the cartilage and labrum. A pincer lesion is acetabular overcoverage (retroversion or a deep socket), more common in middle aged women, where the rim crushes the labrum. Mixed forms are common. Patients report groin pain with prolonged sitting, deep squatting, pivoting and getting in and out of a car. The FADIR test (flexion, adduction, internal rotation) is very sensitive, so a negative test helps rule out intra articular pathology, but it is not specific.

A labral tear causes groin pain with mechanical symptoms (clicking, catching, locking), often with a C sign (the patient cups the lateral hip with thumb and fingers). Most occur in the anterosuperior labrum. Initial treatment is activity modification, avoiding end range flexion and rotation under load, core and hip strengthening and movement retraining. After arthroscopic labral repair or osteoplasty, typical precautions are protected weight bearing (often flat foot or partial weight bearing for 2 to 4 weeks), limits on flexion (often to about 90 degrees) and on external rotation and extension early (to protect the capsule), and avoidance of active straight leg raising and loaded hip flexion, which irritate the iliopsoas.

Lateral hip pain and other conditions

Greater trochanteric pain syndrome (gluteal tendinopathy, with or without trochanteric bursitis) causes lateral hip pain worse lying on the side, climbing stairs and standing on one leg. Single leg stance held for 30 seconds reproducing lateral hip pain is a useful test. Avoid compressive positions (crossing legs, hip adduction stretches such as the iliotibial band stretch) and progress isometric and then isotonic abductor loading. Remember hip conditions in children and adolescents: Legg Calve Perthes disease (avascular necrosis of the femoral head, boys about 4 to 8 years, painless limp), slipped capital femoral epiphysis (obese adolescents, often boys about 10 to 16, knee or groin pain, obligatory external rotation with hip flexion; a non weight bearing emergency referral) and developmental dysplasia (Ortolani and Barlow tests in infants).

Hip fractures

Hip fractures in older adults usually follow a fall from standing height in a person with osteoporosis. The leg is classically shortened and externally rotated. Location determines treatment because of the blood supply to the femoral head, which comes mainly from the medial circumflex femoral artery through retinacular vessels along the neck:

• Femoral neck (intracapsular) fractures can disrupt this supply, leading to avascular necrosis and nonunion. Displaced neck fractures in older adults are usually treated with hemiarthroplasty or total hip arthroplasty; nondisplaced ones with screws.
• Intertrochanteric and subtrochanteric (extracapsular) fractures have good blood supply and are fixed with a sliding hip screw or intramedullary nail.

Modern fixation and arthroplasty generally allow weight bearing as tolerated immediately, and early mobilization (within 24 to 48 hours) reduces complications such as pneumonia, pressure injury, deep vein thrombosis and delirium. Mortality within a year is high, and many patients do not return to prior function, so balance training, strengthening and fall prevention are core goals. If a hemiarthroplasty was done through a posterior approach, posterior hip precautions apply.

Total hip arthroplasty and precautions by approach

The precautions after total hip arthroplasty (THA) follow the capsule and muscles that were cut, because those positions are the ones that let the femoral head lever out of the socket. Many surgeons now relax or drop precautions, especially with the anterior approach, so the surgeon's orders always come first; on the exam, apply the classic set for the stated approach.

Early rehabilitation after THA: ankle pumps, quadriceps and gluteal sets, heel slides within precautions, bed mobility and transfers using adaptive equipment (reacher, sock aid, long handled shoe horn), gait training with a walker progressing to a cane, and stair training (up with the good, down with the bad: the uninvolved leg leads going up, the involved leg and assistive device lead going down). Most cemented and modern cementless implants allow weight bearing as tolerated. Watch for DVT (calf pain, swelling, warmth; the Wells criteria guide referral), dislocation (sudden pain, a shortened and rotated limb, inability to bear weight), infection and leg length discrepancy.

Section 2The knee

Ligament injuries

The anterior cruciate ligament (ACL) resists anterior translation of the tibia on the femur and rotational loads. Most tears are noncontact: deceleration, cutting or landing with the knee near extension, valgus collapse and tibial rotation. Patients report a pop, rapid swelling (hemarthrosis within hours) and giving way. Women have a higher risk, linked to landing mechanics, neuromuscular control and other factors; injury prevention programs that train landing, cutting and hamstring strength reduce ACL injuries. The unhappy triad classically combines ACL, MCL and medial meniscus tears, although lateral meniscus tears are actually more common with acute ACL injury.

The posterior cruciate ligament (PCL) resists posterior tibial translation; it is torn by a fall on a flexed knee with the foot plantarflexed or a dashboard injury. Isolated PCL tears are usually managed nonoperatively with quadriceps emphasis, since the quadriceps pulls the tibia anteriorly; avoid isolated resisted hamstring work early because it pulls the tibia posteriorly. The medial collateral ligament (MCL) resists valgus stress and is injured by a blow to the lateral knee; most isolated MCL tears heal well with a hinged brace and early motion. The lateral collateral ligament resists varus and is often injured with the posterolateral corner, which may need surgery.

Meniscus injuries

The menisci deepen the tibial plateau, spread load and assist stability. The medial meniscus is attached to the MCL and joint capsule, less mobile, and injured more often; the lateral meniscus is more mobile. Only the outer third (the red zone) has a good blood supply, so peripheral tears can be repaired while inner (white zone) tears are usually trimmed. Patients report twisting on a loaded, flexed knee, delayed swelling (over 24 hours), joint line pain and mechanical symptoms (locking, catching). A truly locked knee that cannot extend suggests a displaced bucket handle tear and needs prompt surgical referral. Degenerative tears in middle aged and older adults respond to exercise as well as to arthroscopic partial meniscectomy in most trials. After partial meniscectomy, weight bearing as tolerated and rapid progression are usual. After meniscus repair, protect the repair: limited weight bearing or a brace locked in extension for weight bearing (often about 4 to 6 weeks), limited flexion (often to 90 degrees), and no deep squatting or loaded flexion beyond 90 for about 3 to 4 months.

Patellofemoral pain

Patellofemoral pain is diffuse anterior knee pain around or behind the patella, worse with squatting, stairs (especially descending), running and prolonged sitting (the movie sign). It is common in adolescents and young adults, especially women. Contributing factors include weak hip abductors and external rotators (allowing dynamic knee valgus and femoral internal rotation under the patella), quadriceps weakness, reduced flexibility and excessive load. The Q angle (the angle between a line from the ASIS to the center of the patella and a line from the center of the patella to the tibial tubercle) averages about 13 degrees in men and 18 degrees in women; a larger angle increases lateral pull. The clinical practice guideline supports combined hip and knee strengthening as the core intervention, plus patellar taping and foot orthoses for short term relief, and education on load management. Squat and step exercises are often started in a pain free arc (open chain knee extension is gentler on the patellofemoral joint from 90 to 45 degrees and closed chain exercise from 0 to 45 degrees).

Related conditions: patellar tendinopathy (jumper's knee, pain at the inferior pole with jumping, treated with progressive isometric and heavy slow resistance or eccentric decline squats), Osgood Schlatter disease (tibial tubercle apophysitis in adolescents), iliotibial band syndrome (lateral knee pain in runners, often near 30 degrees of flexion), and patellar dislocation (usually lateral, in young women, often with a medial patellofemoral ligament tear).

ACL reconstruction rehabilitation

Common grafts are bone patellar tendon bone (strong bony fixation, more anterior knee pain and kneeling pain), hamstring tendon (less anterior knee pain, avoid aggressive hamstring loading for about 6 to 8 weeks) and quadriceps tendon. Grafts go through ligamentization: they are weakest about 6 to 12 weeks after surgery as the graft revascularizes, so although the patient feels well, the graft is vulnerable. Accelerated protocols are standard: immediate weight bearing as tolerated (if no meniscus repair), early full extension (loss of extension is the most troublesome complication; a cyclops lesion or arthrofibrosis may be the cause), quadriceps activation with neuromuscular electrical stimulation, and closed chain exercise early.

Open chain knee extension stresses the ACL graft most between about 0 and 45 degrees (the quadriceps pulls the tibia forward near extension), so it is commonly restricted early to 90 to 45 degrees; closed chain exercise in roughly 0 to 60 degrees produces low graft strain because of hamstring cocontraction and compression. Running usually begins around 3 months once there is no effusion, full motion and adequate strength. Return to sport is generally considered no earlier than about 9 months, when a battery of criteria is met: quadriceps and hamstring limb symmetry index of 90 percent or more, hop test symmetry of 90 percent or more (single, triple, crossover and timed hops), full motion, no effusion and psychological readiness. Returning before 9 months and with poor strength symmetry substantially increases reinjury risk.

Total knee arthroplasty

Total knee arthroplasty (TKA) relieves pain in advanced knee osteoarthritis. Goals after surgery: early mobilization (often the day of surgery), weight bearing as tolerated, quadriceps activation, control of swelling, and range of motion targets of full extension and at least about 90 degrees of flexion early (about 105 to 115 for stairs and rising from low chairs, about 110 for many daily tasks). Extension loss is functionally worst, so avoid a pillow under the knee; place a towel roll under the ankle instead. Quadriceps strength is markedly reduced after TKA, and early progressive strengthening plus neuromuscular electrical stimulation improves quadriceps strength and function (supported by the guideline). Continuous passive motion adds little and is not recommended routinely. Watch for DVT, infection, wound problems and arthrofibrosis; a patient who has not reached about 90 degrees by 6 to 12 weeks may be referred for manipulation under anesthesia.

Section 3The ankle and foot

Ankle sprains and the Ottawa rules

The lateral ankle sprain is the most common sports injury. The mechanism is inversion and plantarflexion, and the ligaments fail in sequence: the anterior talofibular ligament (ATFL, weakest and most often torn, taut in plantarflexion), then the calcaneofibular ligament (CFL), and rarely the posterior talofibular ligament. Grade I is a stretch without laxity, grade II a partial tear with some laxity, grade III a complete tear with gross laxity and marked swelling. The anterior drawer test (ATFL) and the talar tilt (inversion) test (CFL) assess laxity. Management: protection and optimal loading early, a semirigid or lace up brace for moderate to severe sprains (better than a cast), early weight bearing, range of motion, then progressive strengthening (evertors and dorsiflexors), and balance and proprioceptive training, which reduces recurrence. Up to a third or more develop chronic ankle instability.

A high ankle sprain injures the distal tibiofibular syndesmosis (anterior inferior tibiofibular ligament) by forced external rotation and dorsiflexion. It causes pain above the ankle, a positive squeeze test (compressing tibia and fibula at midcalf produces distal pain) and external rotation (Kleiger) test, and takes roughly twice as long to recover as a lateral sprain. A medial (deltoid) sprain from eversion is uncommon and often accompanies a fibular fracture.

The Ottawa ankle rules decide when x rays are needed after acute ankle trauma, with sensitivity near 100 percent for fracture. An ankle series is needed if there is pain in the malleolar zone plus any of: bone tenderness along the distal 6 cm of the posterior edge or tip of the lateral malleolus, bone tenderness along the distal 6 cm of the posterior edge or tip of the medial malleolus, or inability to bear weight both immediately and in the emergency department (four steps). A foot series is needed if there is pain in the midfoot zone plus bone tenderness at the base of the fifth metatarsal or the navicular, or inability to bear weight for four steps.

Achilles disorders

Achilles tendinopathy is either midportion (2 to 6 cm above the insertion, the area of poorest blood supply) or insertional. Risk factors include increased training load, older age, obesity, fluoroquinolone antibiotics and reduced calf strength. Morning stiffness and pain that warms up with activity are typical. The guideline supports progressive tendon loading: the eccentric heel drop program (Alfredson) or heavy slow resistance for midportion tendinopathy. For insertional tendinopathy, avoid dropping the heel below the step (dorsiflexion compresses the tendon against the calcaneus), so eccentrics are performed to floor level only. Heel lifts can reduce symptoms short term.

Achilles rupture occurs with sudden push off or landing, usually in middle aged recreational athletes ("I felt like I was kicked"). Findings: a palpable gap, weak plantarflexion (other plantarflexors still work, so active plantarflexion can be present), and a positive Thompson test (squeezing the calf produces no plantarflexion). Both operative and nonoperative care, when paired with early functional rehabilitation in a boot with heel wedges, produce similar rerupture rates. Protect from dorsiflexion past neutral for about 8 to 12 weeks and from forceful stretching for months.

Plantar heel pain

Plantar fasciitis (plantar heel pain) causes pain at the medial calcaneal tubercle that is worst with the first steps in the morning or after rest and eases with walking, then returns after prolonged standing. Risk factors include limited ankle dorsiflexion, high body mass index and prolonged standing. The windlass test (passive great toe extension in standing reproduces pain) is specific. Guideline supported interventions: manual therapy, plantar fascia specific and calf stretching, taping, prefabricated or custom foot orthoses for short term relief, night splints holding the ankle in dorsiflexion for patients with morning pain, education and strengthening. Distinguish tarsal tunnel syndrome (tibial nerve under the flexor retinaculum, burning and numbness in the sole, positive Tinel behind the medial malleolus) and a calcaneal stress fracture (positive squeeze test of the calcaneus, often in runners).

Foot fractures

Foot posture and mechanics

The subtalar joint produces the triplanar motions of pronation (in open chain: eversion, abduction and dorsiflexion) and supination (inversion, adduction and plantarflexion). In closed chain the calcaneus everts while the talus adducts and plantarflexes, and the tibia rotates internally with pronation. During gait the foot pronates from initial contact through loading response to absorb shock and adapt to the ground, as the transverse tarsal joint axes become parallel and the midfoot unlocks. It then supinates from midstance through terminal stance, and the axes converge so the foot becomes a rigid lever for push off. The windlass mechanism assists: extension of the toes at heel off tightens the plantar fascia, raising the arch and inverting the calcaneus.

A pes planus (flat, overpronated) foot is flexible if the arch reappears when non weight bearing or on toe rise, and rigid if not (consider tarsal coalition). Excess pronation is associated with medial tibial stress syndrome, posterior tibial tendon dysfunction, patellofemoral pain and plantar heel pain. Posterior tibial tendon dysfunction is the commonest cause of acquired flatfoot in adults; signs include the too many toes sign from behind and inability to perform a single leg heel raise. A pes cavus (high arched, supinated) foot is rigid and poor at shock absorption, linked to lateral ankle sprains, stress fractures and neurologic disease (Charcot Marie Tooth). Other forefoot terms: hallux valgus (bunion, lateral deviation of the great toe), hallux rigidus (first MTP arthritis limiting extension, which needs about 60 degrees or more for normal push off), Morton neuroma (third web space interdigital neuroma) and claw and hammer toes.

Section 4Normal and pathological gait

Phases and terminology

One gait cycle (a stride) runs from initial contact of one foot to the next initial contact of the same foot. It is divided into stance (about 60 percent) and swing (about 40 percent). A step is from initial contact of one foot to initial contact of the other, so one stride contains two steps. Double limb support occurs twice per cycle, each about 10 percent at normal speed (roughly 20 percent in all); as walking speed increases, double support shrinks, and running has no double support but a flight phase instead. Older adults and people with impaired balance walk with longer double support.

Two vocabularies appear on the exam. The Rancho Los Amigos terms are preferred: initial contact, loading response, midstance, terminal stance, preswing, initial swing, midswing and terminal swing. The traditional terms are heel strike, foot flat, midstance, heel off, toe off, acceleration, midswing and deceleration. They do not line up perfectly; for example traditional heel off begins terminal stance, and traditional toe off ends preswing.

Spatiotemporal values

Joint angles and muscle activity

Muscles in stance mostly work eccentrically to absorb and control motion; propulsion comes from the plantarflexors in terminal stance and the hip flexors in preswing and initial swing. Knowing which muscle is active in which phase lets you predict the deviation produced by its weakness.

Range needed for normal walking, commonly taught: about 30 degrees hip flexion and 10 degrees apparent hyperextension, about 60 degrees knee flexion, about 10 degrees ankle dorsiflexion and 20 degrees plantarflexion, and about 60 degrees or more first MTP extension. Stairs need more knee flexion (about 90 to 105) and rising from a standard chair about 90 to 105 degrees of knee and hip flexion.

Common gait deviations and their causes

Section 5Fractures, weight bearing and orthopedic special populations

Fracture healing

Bone heals by two routes. Secondary (indirect) healing with callus occurs when there is some motion at the fracture, as with casting, intramedullary nails or external fixation. Primary (direct) healing without visible callus occurs with rigid compression plating, where osteons cross the fracture directly. Secondary healing passes through overlapping stages.

Factors that delay healing: smoking, diabetes, poor nutrition, older age, NSAIDs in some studies, corticosteroids, infection, poor blood supply (scaphoid, femoral neck, talus, fifth metatarsal Jones zone, distal tibia), excessive motion and open fractures. A delayed union is slower than expected; a nonunion has stopped healing (often after about 6 to 9 months). Malunion heals in a poor position. Watch after any fracture for compartment syndrome (pain out of proportion and with passive stretch), fat embolism (after long bone fractures, typically 24 to 72 hours: confusion, dyspnea, petechiae), DVT and pulmonary embolism, and complex regional pain syndrome. Exercise prescription during immobilization keeps the joints above and below moving and maintains strength in the rest of the body.

Weight bearing status

Weight bearing orders come from the surgeon and depend on fixation stability more than on the fracture alone. Most hip fractures and arthroplasties allow weight bearing as tolerated; intra articular fractures (tibial plateau, pilon, calcaneus), unstable ankle fractures and many osteotomies require non weight bearing or touch down weight bearing for about 6 to 12 weeks. Patients poorly judge partial weight bearing, so teach it with a scale and recheck. If a patient cannot maintain a NWB restriction safely, a wheelchair may be the safer mobility choice. For gait patterns: three point gait (device and involved limb together) for a restricted limb; two point and four point gaits (reciprocal, with each crutch moving with the opposite limb) for bilateral weakness; swing to and swing through for bilateral lower extremity paralysis. On stairs with crutches, go up with the good limb first and down with the crutches and involved limb first.

Osteoporosis

Osteoporosis is low bone mass with microarchitectural deterioration. The World Health Organization defines it by DXA T score (comparison with young adult peak bone mass): normal T score at or above negative 1.0; osteopenia (low bone mass) between negative 1.0 and negative 2.5; osteoporosis at or below negative 2.5; severe osteoporosis at or below negative 2.5 with a fragility fracture. Z scores compare with age matched peers and are used in children and premenopausal adults. Common fragility fractures: vertebral compression (often thoracic, causing kyphosis and height loss), distal radius (Colles) and hip.

Exercise for bone health combines progressive resistance training, impact or weight bearing activity as tolerated, balance training and posture work (back extensor strengthening reduces vertebral fracture risk). For people with osteoporosis, avoid loaded spinal flexion (sit ups, toe touches, deep forward bending with rotation, some yoga poses) and sudden twisting, which raise vertebral compression fracture risk. Teach hip hinge lifting, home fall prevention and adequate calcium and vitamin D. Pain with mild trauma or a sudden onset of thoracic pain in an older adult with osteoporosis suggests a compression fracture and needs medical evaluation.

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory arthritis of the synovium. Contrast it with osteoarthritis:

During an acute flare (warm, swollen, painful joints), use rest, splinting in a functional position, gentle active or active assisted range of motion (one or two repetitions to maintain motion), isometrics and joint protection; avoid vigorous stretching and resisted exercise through inflamed joints. Between flares, use aerobic exercise, low load strengthening, joint protection and energy conservation. Long term corticosteroid use causes osteoporosis and skin fragility. Atlantoaxial instability from transverse ligament laxity is a serious risk: avoid cervical manipulation and end range upper cervical flexion, and report symptoms such as occipital headache, dizziness, bilateral paresthesia or gait change as possible cord compression.

Amputation level overview

Lower limb amputations in adults are mostly due to vascular disease and diabetes; trauma and tumor are the main causes in younger people. Energy cost of walking rises as the level becomes more proximal, and bilateral and transfemoral amputees often need more help.

Preprosthetic care: residual limb shaping with figure of eight elastic wrapping (tighter distally, diagonal turns, no circular turns that form a tourniquet) or a shrinker, positioning to prevent contractures, strengthening (especially hip extensors and abductors), desensitization, skin inspection of both limbs (the remaining foot is at high risk in diabetes), cardiovascular training and transfer and wheelchair training. Phantom limb sensation is nearly universal and harmless; phantom pain responds to mirror therapy, graded motor imagery and desensitization. A rigid removable dressing protects transtibial limbs and limits edema.

Words worth knowing