Etiologies of pediatric back pain can be classified as musculoskeletal, infectious, inflammatory, neoplastic, and miscellaneous. Of note, idiopathic scoliosis is not a cause of pediatric back pain.
Spondylolysis and spondylolisthesis are the most common causes of back pain in children older than ten years of age. Spondylolysis is a defect in the pars interarticularis, a bony process on the posterior spine, usually caused by repetitive stress. This is most common at L5 and may present as a fracture, stress fracture, or sclerotic change. The incidence is higher in children who participate in activities involving hyperextension of the spine (dancing, figure skating, gymnastics, football, tennis, and weight training).
A patient with spondylolysis may complain of low back pain worsened by activity, often associated with tight hamstrings and buttock pain. Spondylolysis may become complicated by spondylolisthesis, which is a forward slippage of one vertebra upon another (usually L5 on S1). The physical examination may be normal or there may be a palpable step-off in the lower lumbar region, along with tight hamstrings and limited forward flexion.
Excessive kyphosis in the thoracic or lumbar regions is a frequent cause of back pain in adolescents. The patient complains of dull pain over the deformity, which is worsened by activity. On examination, the kyphosis is obvious, accentuated by bending forward, and persists despite the patient’s conscious efforts to stand erect. Lateral spine radiographs will show anterior wedging of at least 5° in three or more adjacent vertebral bodies.
Intervertebral Disk Injury
A disk may be injured (bulging) or herniated, most often at L4–L5 and L5–S1. Patients are usually older than ten years and complain of back pain with or without sciatica (pain down the back of the thigh). Physical examination findings include decreased lumbar lordosis, limited forward flexion, paraspinal muscle spasm, and a positive straight leg-raising test (see below).
Lumbar Sacral Sprain
This is an injury or tearing of the ligaments and/or muscle fibers (interspinous or paraspinal) that connect one vertebra to another or support a vertebra. The most common mechanism of injury is a sudden twisting motion in an inflexible and overweight patient. This injury can also occur in children who carry heavy backpacks.
Diskitis is a rare condition that occurs most often in younger children (average three years old). The patient may present with fever, malaise, low back pain, refusal to walk or crawl, and associated hip or abdominal pain. On physical examination, there may be tenderness over the involved disk, decreased back motion, and pain with hip flexion. The WBC is often normal, but the ESR and CRP are usually elevated. The blood culture is usually negative but sometimes yields an organism, most often S. aureus.
Vertebral osteomyelitis presents similarly to diskitis, but is more common in the older child (average seven years old). Unlike diskitis, the blood culture is positive in about 50% of cases (usually S. aureus). Uncommon entities, such as B. Henselae, Salmonella, and tuberculosis (TB), can also cause vertebral osteomyelitis but generally are associated with recognized risk factors (cat scratch, sickle cell anemia, risks for TB).
An epidural abscess most often results from hematogenous spread of bacteria into the epidural space, but it can also occur secondary to direct extension from an underlying osteomyelitis or superinfection of a traumatic hematoma. In some cases, there will be no fever or back pain, so the patient may present later, with neurologic symptoms. The microbiology of epidural abscesses is similar to that of vertebral osteomyelitis. Children with infections (i.e., abscess or pyomyositis) involving the paraspinal or pelvic muscles often complain of back pain. In addition, various non-orthopedic infections, such as pyelonephritis, pneumonia, and pancreatitis, can occasionally present with back pain.
Pneumonia, endocarditis, pyelonephritis, pelvic inflammatory disease, retrocecal appendicitis, pancreatitis, and myositis of spinal muscles may also cause back pain.
Ankylosing spondylitis is a spondyloarthropathy involving the sacroiliac joints and lumbar spine. It is most common in adolescent boys, and the majority of affected patients are HLA-B27 positive. The patient may experience transient arthritis of large joints, followed by back involvement later in the disease course. Pain in the lower back, hips, and thighs is associated with morning stiffness that is relieved by movement. There may also be an acute iridocyclitis and/or aortitis. The spinal involvement begins in the sacroiliac joints and ascends progressively to involve the rest of the spine, including the cervical vertebrae. In contrast, juvenile idiopathic arthritis (JIA) affects the cervical spine, but spares the lumbar spine.
A patient with inflammatory bowel disease may have associated spondylitis similar to ankylosing spondylitis. The patient may present with low back pain prior to the onset of gastrointestinal symptoms.
A spinal tumor is a rare but concerning cause of back pain in children. The majority are benign, including osteoid osteomas, eosinophilic granulomas, and unicameral bone cysts. Malignancies include Ewing sarcoma, osteosarcoma, and metastatic lesions (neuroblastoma, etc.). A history of nighttime pain, pain not associated with activity, or a painful scoliosis raises the concern of a tumor. Leukemia may present as persistent back pain secondary to infiltration of the bone marrow.
Reflex Sympathetic Dystrophy (RSD)
The hallmark of this syndrome is severe pain associated with autonomic dysfunction (swelling, edema, skin color changes, mottling). RSD may occur in the back after trauma, although the initial injury may be a sprain or a disk injury, with ongoing pain out of proportion to what is expected for the original injury (allodynia, dysthesias).
A thorough history is essential in determining whether the patient’s back pain requires urgent or immediate intervention. Determine the onset of the pain, its timing, severity, and radiation, as well as factors that alleviate or trigger it. Inquire about sports participation, including the intensity of the involvement and the initiation of any new sports. Ask specifically about trauma. Evaluate the child’s activity level since the onset of symptoms; back pain that forces the child to refrain from usual activities requires a thorough evaluation.
Determine whether the pain is related to sleep or resting in bed. Specific difficulty in moving from side to side in bed may suggest a disk problem or lumbar sprain. A patient awakened and kept awake by back pain must be thoroughly evaluated for a tumor, infection, or inflammatory condition. In contrast, back pain from overuse syndromes, muscle pain, Scheuermann’s disease, or spondylolysis (with or without spondylolisthesis) usually improves with rest.
Always check for the presence of systemic symptoms, such as fever, malaise, irritability, or weight loss. In these children, ask about pets (i.e., kittens) and risk factors for TB such as travel to or from endemic areas. A positive history for ankle or foot weakness, changes in bowel or bladder function, and/or an altered gait, is suggestive of neurologic impairment. Ask about medications or therapies already tried, including chiropractic manipulation and acupuncture. Note any chronic medications that cause osteoporosis (i.e., steroids), because these increase the risk for fracture.
Have the patient undress down to his or her underwear and observe the gait and posture. Note any muscle asymmetry and signs of splinting. Assess the back for a midline defect or lesion such as a tuft of hair or hemangioma. Carefully check for tenderness by palpating over the vertebrae, spinous processes, vertebral spaces, and interspinal ligaments, as well as the shoulders and paraspinal muscles.
For the lumbar spine, evaluate forward flexion, lateral rotation, lateral bending, and extension. The forward bend test helps reveal any deformities of the spine; low back pain increased by hyperextension suggests spondylolysis and/or spondylolisthesis.
Perform a complete neurological examination, paying particular attention to symmetry and deep tendon reflexes (knee jerk and ankle jerk). Look for quadriceps and hamstring asymmetry, which can result from a low back problem. Check the strength of each lower extremity, isolating each joint and comparing it to the other: hip (flexion, extension, abduction, and adduction), knee (flexion and extension), and ankle/foot (plantar flexion/dorsiflexion, inversion, eversion). Lower limb weakness may be a sign of spinal cord compression and is a particularly ominous finding requiring immediate attention. Also check for signs of meningeal irritation (Kernig’s and Brudzinski’s signs).
A straight leg-raising test will frequently be positive in a patient with disk herniation: with the patient supine, grasp the ankle, and with the knee held in extension, bring the leg upward to assess range of flexion of the hip joint. Note the angle and location of any elicited pain. Then repeat the maneuver and dorsiflex the foot as the painful angle is approached, which will aggravate the pain. Back pain radiating down the back of the leg indicates sciatic nerve irritation and a herniated disk.
A patient with abnormal physical findings, pain that has lasted three months or more despite conservative treatment, nighttime or constant pain, or pain due to significant trauma requires radiological evaluation. Obtain anteroposterior and lateral radiographs of the spine and add oblique lumbar spine views if spondylolysis is suspected. Obtain a technetium-99 bone scan if a febrile patient has an examination that is consistent with diskitis or osteomyelitis, if the plain films are normal. A CT scan can further define spinal pathology located by bone scan and a fine-cut CT scan (1–3 mm cuts) is useful in diagnosing and evaluating spondylolysis. Obtain an MRI for any abnormal neurologic findings. The MRI is a valuable tool in evaluating spinal cord tumors, tethered cords, disk herniations, diskitis, and other spinal pathology, but clinically insignificant disk herniations or degenerative disk disease may be over-read. A concern about spinal cord compression is one of the few indications for an emergent MRI.
The priority is to identify conditions requiring immediate treatment, including mass lesions, diskitis, or osteomyelitis. If the patient has any of the clinical features outlined in Table 17.1, arrange for immediate radiological evaluation (see above) and consultation with a neurologist and/or orthopedist. Immediately consult a neurosurgeon if the patient has any signs of spinal cord compression.
|Age <4 years||Benign back pain very uncommon in this age|
|Duration >1 month||Concern for neoplasm/infection|
|History of malignancy||Concern for spinal metastases|
|Neurological abnormalities: foot or ankle weakness, altered gait, abnormal DTRs or Babinski, asymmetric strength, meningeal signs, bladder or bowel dysfunction||Concern for root compression/epidural abscess|
|Nocturnal or constant pain||Concern for spinal tumor or infection|
|Pain radiating below buttocks||Concern for nerve root compression|
|Point tenderness over spine or intervertebral space||Concern for spinal infection or fracture|
If an older child with back pain for less than one month appears well, has a normal neurological examination, and does not have point tenderness, nighttime pain, or restriction of daily activities, refer him or her to a primary care provider, orthopedist, or sports medicine specialist for follow-up within one week. In general, management will include referral to a physical therapist, avoidance of the offending activity (usually hyperextension), and occasionally, a back brace. However, bed rest has virtually no role in the management of back pain. Encourage the patient to walk and go to school as soon as possible. Reserve ibuprofen (10 mg/kg q 6h) for acute pain (sprains, fractures, disk injuries).
Indications for Admission
Common Orthopedic Injuries
Clavicular fractures are particularly common in newborns (5 per 1000 births). They are associated with a breech or difficult delivery but may not be noticed until about one week of age, when a grossly obvious callus is found in the area of the fracture. In older children, they are caused by a fall on an outstretched hand (FOOSH) or by a direct blow, and present with swelling and tenderness. It is important to tell parents to expect a large, possibly tender, swelling (callus) 7–10 days after the injury. Most clavicle fractures heal with minimal supportive treatment. Either immobilize the arm with a sling or apply a figure-of-eight clavicle splint. A full return of function requires 3–4 weeks.
True sternoclavicular and acromioclavicular (AC) joint dislocations are relatively uncommon in children and more often are, in fact, physeal fractures. However, the treatment is usually the same (outpatient management with a sling). Rarely, the clavicle may be severely displaced and require reduction. Medial clavicular injuries require particular attention when displaced posteriorly because they may compress the trachea, great vessels, and brachial plexus. An emergent CT scan and orthopedic consultation are required if this injury is suspected.
Shoulder dislocations are rare in childhood, as the proximal humeral epiphysis is weaker than the shoulder joint capsule. As the growth plate closes, shoulder dislocations can occur with a FOOSH, forced abduction of an externally rotated arm, or a posterior blow to an elevated, abducted arm. Anterior dislocation is the most common, presenting with the arm held slightly abducted and in external rotation, with a squared-off appearance to the shoulder. There may be numbness and tingling of the arm. The recurrence rate approaches 90% after an initial dislocation in a teenager.
Except for a patient with a history of a shoulder dislocation, obtain radiographs prior to reduction as a superior humeral fracture can resemble a dislocation. Test for neurovascular compromise before and after any attempt at shoulder reduction by comparing bilateral brachial pulses and examining sensation over the deltoid muscle. Reduce an anterior shoulder dislocation with the Stimson method. After providing adequate sedation (pp. 715–722), have the patient lie prone on a stretcher, with the affected arm hanging down. Application of a 5–10 lb weight to the arm will cause gradual reduction over 15–30 minutes. During the reduction rotate the inferior edge of the scapula medially with gentle pressure. Place the arm in a sling and obtain post-reduction radiographs to evaluate for an associated fracture.
Injuries to the proximal humerus usually involve the growth plate or metaphysis, occurring after a FOOSH. Neurovascular compromise is rare. This area has tremendous remodeling potential, so growth disturbances are uncommon. Angulations up to 30° and displacement of up to 50% may not require reduction. Treat with a sling and immobilization. More significantly displaced fractures require reduction.
Overhand sports (baseball pitching, swimming, etc.) can place stress and injure the proximal humeral physis by the same mechanism that causes a rotator cuff injury in older athletes. Typically, the pain has a gradual onset over months and is most severe when performing the overhand activity. Patients often present with tenderness over the proximal humerus, but many are asymptomatic at rest. Radiographs of the humerus may be normal or show widening of the physis, fragmentation, demineralization, or sclerosis. Treat with rest, ice, analgesia, and a slow return to sports.
These fractures are less common than proximal and distal humeral fractures. They can be associated with a unicameral bone cyst of the humerus. Carefully assess the radial nerve (wrist dorsiflexion), which may be injured as it passes close to the bone in the distal half of the shaft. Treat with a sling, as few of these injuries require reduction.
If a fracture is suspected, splint the extremity and obtain true AP and lateral radiographs. If there is an obvious deformity, do not test passive range of motion, because of the risk of displacing a fracture. Apply ice and elevate the extremity above the level of the heart to reduce swelling.
Since a child’s elbow is a maze of growth centers, surrogate markers for fracture are often helpful when a fracture line is not obvious. On the lateral radiograph, the anterior humeral line normally intersects the middle third of the capitellum on a true lateral; if it does not, suspect a fracture. Similarly, the radius typically aligns with the capitellum; if it does not, suspect a dislocation. Also on the lateral radiograph, a normal elbow will have a visible thin anterior fat pad that is flush up against the humerus. The posterior fat pad normally lies deep in the olecranon fossa and is not visible when the elbow is flexed. When the joint capsule is distended by blood or an effusion, however, the anterior fat pad is lifted away from the humerus (sail sign) and the posterior fat pad becomes visible as it is pushed posteriorly out of the olecranon fossa.
These account for about two-thirds of elbow fractures and typically occur in children <10 years of age who FOOSH with a hyperextended elbow. Fractures of the distal end of the humerus pose a high risk (12%) of neurovascular compromise, most often involving the median and radial nerves. Supracondylar fractures may present with ischemic pain in the forearm from a compartment syndrome or injury to the brachial artery. An attempt to extend the fingers may cause considerable pain. This is a more reliable sign of ischemia than the absence of the radial pulse. Prompt orthopedic intervention is required to prevent a Volkmann’s contracture. If compartment syndrome is suspected, arrange for immediate measurement of compartment pressure.
Treat nondisplaced fractures with in situ immobilization; these heal well. Displaced fractures require accurate anatomic reduction and immobilization, often necessitating pin fixation. Admit a patient with a displaced supracondylar fracture and/or marked swelling for repeated neurovascular checks.
These represent Salter IV fractures involving both the growth plate and the elbow joint. Lateral epicondyle fractures are one of the few types of pediatric fractures that may proceed to nonunion. Radiographs may not reveal the true extent of the displacement; an arthrogram may be required. Suspect a fracture if there is instability on valgus and varus stress. Treat nondisplaced fractures with immobilization, but displaced fractures require surgery for precise anatomic reduction.
Little League elbow is a common overuse injury that results in an apophysitis about the medial epicondyle. The act of throwing places excessive valgus stress on the medial epicondyle. Typically, the pain worsens during throwing and improves with rest. Examination may be normal or demonstrate point tenderness over the medial epicondyle. Radiographs may be normal or show a widened physis, fragmentation, or hypertrophy about the medial epicondyle. Treatment consists of rest, ice, and analgesia similar to other overuse injuries.
Fractures of the Proximal Radius
These can also occur from a FOOSH. Characteristic findings are pain over the radial head and decreased forearm pronation and supination. Neurovascular compromise is unusual. Other parts of the elbow are frequently injured (50%), so obtain a dedicated ipsilateral elbow radiograph if only a forearm x-ray was taken. Normally, a line drawn through the shaft of the radius always intersects the capitellum, no matter how the arm is positioned. In the absence of any angulation or displacement, treat symptomatically with a sling and range of motion exercises beginning the next day. Otherwise, consult an orthopedist for evaluation and possible reduction because of the increased risk of avascular necrosis and subsequent loss of function.
Nursemaid’s Elbow (Radial Head Subluxation)
This is a common problem that typically occurs when a young child’s (1–3 years) arm is suddenly pulled while the elbow is extended and the arm pronated, or after a minor fall. It may be recurrent, but can be managed without radiographs or orthopedic consultation. The patient will often be comfortable but refuse to actively flex the elbow, preferring an extended, internally rotated position. Examine the affected arm in the extended position to ensure there is no swelling or tenderness around the elbow or wrist prior to any attempt at reduction. If the patient has any tenderness with palpation, obtain radiographs to evaluate for fracture.
To reduce a nursemaid’s elbow, cup the elbow in one hand and the wrist in the other. Rapidly supinate the forearm while simultaneously flexing the elbow. Usually a click is felt, and within 10–15 minutes (sometimes longer) the child actively flexes the elbow. If the success of the reduction is in question, obtain radiographs of the elbow to evaluate for an occult fracture before attempting to reduce again. Note some patients with nursemaid’s elbow, however, will demonstrate a joint effusion on elbow radiographs. Hyperpronation of the forearm is another technique useful for reduction.
Posterior dislocations of the elbow are the most common type, although neurovascular compromise is unusual, but critical to identify. Contact orthopedics for reduction. Afterward, obtain post-reduction radiographs to look for associated fractures, which occur frequently, and admit the patient for observation for compartment syndrome.
These are the most common fractures of childhood and are usually caused by falls. About 75% occur in the distal third of the forearm and most others in the middle third. Over half are greenstick fractures presenting with pain and swelling without significant deformity. If only one forearm bone is fractured, image the elbow and wrist to evaluate for concurrent dislocation of the other bone.
Treat a nondisplaced fracture with splinting or casting. A displaced or angulated fracture requires closed reduction and casting under sedation. Use a long arm cast for a midshaft fracture, but a short arm cast will suffice for a distal fracture. In a patient under ten years of age, the forearm and wrist will remodel with no lasting deformity, if proper reduction is achieved. Treat a buckle fracture of the distal radius with a removable volar splint to allow for increased comfort and early return of function.
Wrist and Hand Fractures
Carpal fractures are uncommon in children, although the scaphoid (navicular) is the most frequently fractured, usually by a FOOSH (see Hand Injuries, pp. 744–749). Carpal fractures present with pain in the wrist, with deformity or swelling, and sometimes without definite radiologic abnormalities. Point tenderness in the anatomic snuff box suggests a scaphoid fracture, as does pain in the snuffbox with axial loading of the thumb. Obtain a wrist radiograph with dedicated scaphoid views. Treat nondisplaced scaphoid fractures with a thumb spica cast. Displacement is a sign of wrist instability and requires open reduction and internal fixation. Radiographs may not detect subtle scaphoid fractures so place all patients with snuffbox tenderness and negative x-rays in a thumb spica splint.
Metacarpal fractures are usually the result of fighting. The neck of the fifth metacarpal is most often affected (boxer’s fracture). The patient may present 1–2 days after the injury with swelling of the dorsum of the hand and decreased range of motion. In the absence of significant angulation or displacement, treat with a radial and/or ulnar gutter splint depending on the affected bone. Consult orthopedics for multiple metacarpal fractures or when there is an associated rotational deformity causing finger overlap.
Finger Fractures and Injuries
Most finger fractures are simple, nondisplaced distal phalangeal shaft injuries. A subungual hematoma is often associated with the fracture due to crush injury. Reduction is indicated if there is a displaced phalangeal fracture with >20° of volar angulation. Use a dorsal splint to immobilize a fractured digit, maintaining the MCP joints at 35–40° of flexion, ensuring that the rotational alignment of the digits is preserved. Injuries to the base of the thumb may require a thumb spica cast, and significantly unstable fractures may require pin fixation.
Finger dislocations are easily recognized from the deformity of the digit. The most frequently dislocated metacarpophalangeal joint is the second. Anesthetize the finger using a digital nerve block and reduce the finger dislocation with simple traction. Afterward, splint for 7–10 days.
Fractures of the pelvis are rarely isolated, occurring most often in a multiple-trauma victim who has pain with movement or palpation of the pelvis. There may be associated injuries to the viscera and bladder or a vaginal or rectal laceration. If there is any suspicion of a pelvic injury, obtain pelvic radiographs as part of a multiple trauma work-up. Most pelvic fractures are stable, so treatment is directed toward fluid resuscitation and hemodynamic stabilization. Pelvic fractures that cause widening of the sacroiliac joints can result in a substantial amount of blood loss. For a patient whose pelvic ring is substantially disrupted or who remains hemodynamically unstable, apply lateral pressure with a pelvic binder, or bedsheets, wrapped around the femoral heads.
Do not insert a urinary catheter in any patient with blood at the urethral meatus, a high-riding prostate or scrotal hematoma, or a vaginal laceration because of the risk of converting a partial urethral tear into a complete one. Consult urology for an emergent urethrogram. For a female, because the urethra is so short, urethroscopy may be more helpful.
Pelvic apophyseal injuries are common and usually isolated injuries in children. These occur after an acute strong contraction of the attached muscle, most often in an athlete who presents with localized pain. Overuse injuries (apophysitis) are more chronic and improve with rest. The anterior superior and inferior iliac spines, the iliac crest, and the ischial tuberosity are the sites most often involved. Pelvic radiograph findings vary from a widening of the physis to complete avulsion. Treat simple apophyseal injuries symptomatically with analgesia, ice, and rest. Consult an orthopedist for complete avulsion fractures.
Hip fractures are rare, occurring with significant high-energy trauma. In 30% of cases, there are associated injuries. Observe how the patient holds the leg while lying supine. The affected leg is shortened and externally rotated, while the hip may be flexed. Obtain AP and lateral (frog-leg) radiographs. Prompt surgical reduction is required to prevent avascular necrosis, especially with femoral neck fractures and hip dislocation. A delay in treatment can cause permanent deformity.
A traumatic hip dislocation is rare, and most are posterior. It occurs when the hip is flexed and forced posteriorly (kneeling football player, sitting in motor vehicle). It is associated with significant morbidity if not relocated within six hours.
Femoral Shaft Fractures
Typically, femur fractures are easily identified, presenting with swelling, deformity, and tenderness in the thigh. Occasionally, they may be detected while evaluating a crying child who refuses to bear weight on the affected leg. Look for other injuries, such as ipsilateral hip dislocation, femoral neck fracture, epiphyseal injury, tibial fracture, and fracture of the contralateral femur. While a femoral shaft fracture can occur with falls and play, suspect child abuse in non-ambulatory children or those with other signs of inflicted trauma (pp. 604–608). When caused by high-energy trauma, a substantial amount of blood can extravasate into the surrounding tissue and result in shock. Consult orthopedics for definitive management.
The knee is a common site of sports injuries, especially in football players and skiers. The history of the mechanism of injury, including the position of the knee and foot at the time of injury, and whether there was any contact, help suggest the most likely diagnosis. The patient may complain of pain or swelling or may be limping or unable to bear weight. A sensation of “tightness” behind the knee suggests a small effusion.
Obtain AP and lateral radiographs of the knee to rule-out fracture in patients that have any bony tenderness, are unable to bear weight, or cannot flex their knee to 90°. Order an additional patellar skyline view if the patient has tenderness over the patella. Obtain a CT scan of the knee when the clinical suspicion for a fracture is high but the radiographs are not definitive. It is quite common for an acutely injured knee to be so swollen and painful that an examination is impossible. Use the RICE protocol with a knee immobilizer, and refer the patient to an orthopedist for definitive diagnosis and treatment. If a fracture is present, immediate consultation is required.
Knee sprains are rare in young children; they occur more frequently in adolescents with closed or closing growth plates. The medial collateral ligament (MCL) is the most common site of sprain, caused by a lateral blow to the knee. Injuries to the anterior cruciate ligament (ACL) can occur without contact by abrupt deceleration maneuvers, jumping, missed landing, or “cutting” maneuvers such as those seen in basketball, football, or tennis. Lateral collateral ligament (LCL) and posterior cruciate injuries are less common.
After the initial evaluation of the injured extremity, the integrity of the knee ligaments must be checked. For each ligament, assess the range of motion and whether there is a definite endpoint, using the other side as a reference. With the patient supine, the hip extended, and the knee at 0° (fully extended), place one hand above the ankle and the other on the lateral aspect of the distal femur. Abducting the lower leg then causes valgus knee stress, testing the MCL. Place the upper hand on the medial aspect of the distal femur, and adduct the lower leg (varus stress, LCL). If there is instability (no definite endpoint), stop the examination; if the knee is not unstable, repeat the exam at 30° flexion. MCL sprains cause medial pain; LCL injuries result in pain on the lateral side of the knee.
Next, test the cruciate ligaments by performing a Lachman test. With the knee flexed 20°, stabilize the femur with one hand and draw the tibia downward with the other. A sharp endpoint indicates ACL integrity. Then flex the hip to 45° and the knee to 90° with the foot flat on the table. Sit on the patient’s toes, place four fingers of both hands on either side of the patient’s calf and your thumbs on the femoral condyles, and pull the tibia forward (anterior draw, ACL), feeling for a definite endpoint. Then push it backward (posterior draw, posterior cruciate).
With ACL tears the patient or bystanders may report having heard a “pop” or “snap,” the patient refuses to bear weight, and swelling begins almost immediately. Treat knee sprains with a knee immobilizer and crutches. Radiographs may demonstrate an avulsion fracture of the superior lateral tibia (Segond fracture).