I. Lateral Patellar Dislocation
A. Overview/epidemiology
1. Terminology and definitions
a. Dislocation—A traumatic episode during which the patella loses its previous confinement in the trochlear groove.
b. Subluxation—An active event during which the patella is partially translated outside the confines of its groove.
c. Translation (lateral/medial)—The passive position of a patella in relation to the groove. The term is used to describe the position of the patella on radiographs or its passive position during physical examination.
d. Tilt—The position of the patella in the horizontal, or axial, plane. The term is used to describe the position of the patella on radiographs or during physical examination.
e. Limb alignment—A reflection of the three-dimensional geometry of the lower limb. The forces acting on the patellofemoral (PF) joint are dependent on limb alignment, which includes knee varus/valgus, flexion/extension, and tibial and femoral version or rotation.
2. Epidemiology
a. Epidemiologic studies are scarce, but lateral patellar dislocation appears to occur most frequently in the second and third decades of life.
b. First-time lateral patellar dislocations occur equally in men and women.
c. Recurrent PF dislocations occur more frequently in women; the reasons for this are speculative.
3. Risk factors
a. Patella alta
b. Trochlear dysplasia
c. Excessive lateral patellar tilt (measured in full extension)
d. Excessive distance between the tibial tuberosity and the center of the femoral sulcus (measured in full extension)
B. Pathoanatomy
1. The mechanism of injury is typically a noncontact pivoting force with the knee near extension and the foot/lower leg externally rotated. The patient may feel the patella move out of place and may instinctively contract the quadriceps muscles, which will often reduce the patella back into the groove.
2. In the absence of previous patellar surgery and/or significant dysplastic features of the extensor mechanism, the direction of the dislocation is lateral.
3. A large hemarthrosis is common, with tearing of the medial retinacular restraints.
4. The medial PF ligament (MPFL) is the main passive restraint to lateral translation of the patella; it is torn in lateral patellar dislocations.
C. Evaluation
1. Physical examination
a. A first-time traumatic PF dislocation will present with a large effusion and medial-sided tenderness along the torn medial retinacular structures. Lateral-sided tenderness is often variable.
b. The absence of swelling after a PF dislocation implies that the medial retinacular structures are lax to the degree that the patella can laterally translate outside of the groove without tearing any structures. This can occur with recurrent PF dislocations or with excessive tissue laxity (eg, Ehlers-Danlos syndrome).
c. Inhibition of the quadriceps is very common in both acute and recurrent PF dislocations. The patient often resists or performs poorly when asked to perform a straight-leg raise test.
d. Passive patellar translation in the medial and lateral directions is an important examination maneuver.
i. Patellar motion is measured in quadrants of translation, with the midline on the patella being zero. Lateral translation of the medial border of the patella to the lateral edge of the trochlear groove represents two quadrants of passive lateral translation.
ii. Normal motion is less than two quadrants of medial and lateral translation; however, it must be compared with the opposite side, particularly in the absence of present or past injury to the contralateral limb.
iii. During this maneuver, passive lateral translation is often painful and/or resisted by the patient. This is known as lateral patellar apprehension.
iv. Excessive lateral translation does not confirm the presence of a dislocation, as it may be normal for the patient. However, a PF dislocation cannot occur in the absence of excessive lateral translation, making this a powerful physical examination feature.
e. Lateral patellar tilt—The lateral border of the patella cannot be lifted to the level of the horizon. This is a qualitative test, and is difficult to quantify on physical examination. When present, lateral patellar tilt is suggestive of lateral retinacular tightness.
f. Quadriceps angle (Q angle)
i. The Q angle is formed by the intersection of a line drawn from the anterosuperior iliac crest to the center of the patella and a line drawn from the center of the patella to the tibial tuberosity.
ii. There is considerable intra- and inter-observer variability in measurement of the Q angle, as well as debate in the literature as to the limits of its normal value. This makes use of the Q angle as an examination variable difficult.
iii. On average, the Q angle is greater in females (15° ± 5°) than in males (10° ± 5°).
g. The tubercle-sulcus angle represents the relationship of the center of the sulcus to the tibial tuberosity.
i. At 90° of flexion, the tubercle-sulcus angle should be 0°, ie, the tibial tuberosity should lie directly under the center of the femur. This may be a more reliable way to look for excessive lateral tibial tuberosity placement on physical examination.
ii. Although quantification schemes have been reported, use of the tubercle-sulcus angle as a way to quantify excessive lateral tibial tuberosity placement has not been widely accepted.
h. Limb version should be evaluated in all non-acute injuries of the PF joint.
i. Femoral version is best examined with the patient in the prone position; internal rotation in excess of external rotation suggests femoral anteversion.
ii. Tibial version can be measured as an angle between the bicondylar femoral axis and the bicondylar tibial axis.
i. J-tracking—Excessive lateral patella translation in terminal extension
i. In active flexion, the patella "hops" into the groove.
ii. J-tracking is often associated with patella alta.
2. Imaging—The PF joint can be evaluated in three planes: coronal (from the front), sagittal (from the side), and/or axial (cross-section).
a. Coronal plane views are helpful in evaluating knee alignment and limb alignment.
i. Knee varus/valgus is most commonly measured on a weight-bearing radiograph of the knee.
ii. Limb alignment in the coronal plane is best reflected in a weight-bearing radiograph in which the hip, knee, and ankle are visualized.
b. Sagittal plane views are helpful in measuring patellar height and trochlear geometry.
i. Patellar height is usually measured on a lateral plain radiograph. Values will differ, depending on whether there is a quadriceps contracture. Most often, a weight-bearing radiograph is used, which presumes a quadriceps-relaxed mode.
ii. More than a dozen methods of measuring patellar height are described in the literature. In the United States, the Insall-Salvati (
Figure 1) and Blackburne-Peel (
Figure 2) methods are used most often. These two methods have been criticized because they do not take into consideration the relationship between the patella and the femur (in particular, the patella and the trochlear groove). No method of measuring the relationship between the patella and the trochlear groove has been clinically accepted with wide use.
iii. Although the mechanism by which patellar height alterations influence PF biomechanics continues to be studied, a positive correlation exists between patella alta and PF instability, PF arthritis, and PF pain.
iv. Trochlear shape is most commonly obtained
[Figure 1. The Insall-Salvati method of measuring patellar height. This method uses the ratio of A/B, where A is the length of the posterior surface of the patellar tendon from the inferior pole of the patella to the tibial tuberosity and B is the greatest diagonal length of the patella. The normal value is 1.0 ± 0.2. This measurement does not take the tibiofemoral joint line into consideration.]
on a true lateral radiograph (a weight-bearing view), in which there is perfect superimposition of the posterior aspect of the medial and lateral condyles. Three contour lines can be seen anteriorly, which represent the anterior curves of the medial and lateral condyles and the floor of the sulcus. These lines are used to define the trochlear depth; the crossing sign helps characterize the length and depth of the trochlea and the trochlear boss, or bump.
v. Trochlear dysplasia (
Figure 3) is most often seen in the region of the proximal trochlea, an area that is not well visualized on the axial views taken in deeper flexion.
c. Axial views are helpful in evaluating limb version or patellar position (translation and tilt).
i. Limb version is most often visualized by comparing CT slices at several levels: the femur at the level of the greater trochanter, the distal femur, and the proximal and distal tibia. Femoral anteversion of 15° is normal in adults; anteversion >10° above normal is believed to warrant surgical correction if the clinical symptoms dictate. The value of tibial torsion that warrants surgical correction is less well defined.
[Figure 2. The Blackburne-Peel method of measuring patellar height. This method uses the ratio of A/B, where A is the perpendicular distance from the extension of the tibial plateau line to the inferior edge of the patellar articular surface and B is the length of the patellar articular surface. The normal value is 0.8 ± 0.2. This method takes the tibiofemoral joint line into consideration, and, as such, it is often used to measure patellar height after knee joint arthroplasty.]
ii. CT is often used to measure the distance between the tibial tuberosity and the center of the femoral sulcus. A value of >20 mm of lateral displacement is considered excessive lateralization.
iii. Patellar tilt can be viewed best on an axial radiographic image. Such malalignments are most often viewed radiographically when they are defined in relation to the femoral condylar anatomy.
iv. CT measures patellar tilt in relation to the posterior condylar line (
Figure 4). A value >20° is considered excessive lateral patellar tilt.
[Figure 3. True lateral weight-bearing radiograph of the knee, with the posterior femoral condyles perfectly overlapped. The white line outlines the trochlea, which crosses the anterior cortex, representing a femoral sulcus that is both shortened and shallow (trochlear dysplasia).]
D. Treatment
1. First-time patellar dislocation
a. Nonsurgical management is the cornerstone of treatment for this injury.
i. Aspiration should be done only if a tense effusion is present. The presence of positive fat globules in the serosanguinous effusion is indicative of a fracture.
ii. Osteochondral fractures occur as the laterally dislocated patella relocates. In this mechanism, the medial patellar facet hits the lateral femoral condyle. This is the location where bony fragmentation should be sought; it is most easily recognized on an axial radiograph. Small osteochondral and chondral fractures are most readily identified by MRI.
b. Surgical
i. If free bony fragments are evident on imaging, arthroscopic examination is the next appropriate step. Depending on the size and location of the fragment, debridement or reduction with fixation is recommended.
ii. The MPFL is the major structure torn in lateral PF dislocations. Although acute repair
[Figure 4. Axial CT of the knees showing patellar tilt. A line is drawn along the posterior femoral condyles, which shows the "Roman arch" of the notch. A line is then drawn along the long axis of the patella. If the angle between the two lines is >20°, excessive lateral tilting is present.]
of this ligament is gaining popularity, no clinical studies currently support acute repair versus nonsurgical management for first-time dislocations.
2. Recurrent patellar dislocation
a. When nonsurgical management fails, surgery is recommended.
b. Evidence-based medicine guiding surgical choices is sparse in the current literature.
c. Reconstruction of the MPFL using allograft or autograft tissue is a common clinical procedure for recurrent PF instability.
i. The most common graft choice is the gracilis or semitendinosus tendon, which represents a stronger and stiffer graft than the native MPFL.
ii. Outcomes studies and long-term results of this procedure are sparse.
d. Surgical correction of risk factors
i. Patella alta 
distal tibial tuberosity transfer
ii. Excessive tibial tuberosity lateralization medial tibial transfer
iii. Severe trochlear dysplasia trochleaplasty
iv. Excessive limb rotation femoral/tibial derotation osteotomy
v. Medial patellar dislocation and medial PF arthritis are major complications of overcorrection of lateral patellar dislocation. Medial patellar dislocation is almost exclusively a result of prior surgery.
E. Physical therapy/rehabilitation
1. When acute injury is associated with joint effusion, RICE (rest, ice, compression, and elevation) principles are advised to regain joint motion.
2. Immobilization is advised only when quadriceps function limits safe ambulation.
3. Dysplasia of the vastus medialis oblique (VMO) muscle is associated with PF instability.
a. This physical examination feature is a product of the muscle's bulk and position in relation to the patella.
b. The usefulness and success of selective VMO strengthening practices is not supported in the current literature.
4. Strengthening of the knee and limb musculature for improvement of PF function has been shown in the literature to be successful; therefore, its use as a first-line treatment for PF disorders continues to be advocated.
5. Control of the limb under the pelvis is currently the most successful strengthening scheme for the treatment of PF disorders, including PF instability. This includes strengthening of the "core" musculature (the gluteal and abdominal muscles) as well as muscles used in extension and abduction of the hip.
6. Use of a patellar stabilizing sleeve to help control patellar position and joint effusion is recommended.
7. Restoration of proprioception and balance is recommended.
8. Orthotic control should be considered for the flexible pronated foot.
II. Anterior Knee Pain (Patellofemoral Pain)
A. Overview/epidemiology
1. Pain is an unpleasant sensory and emotional experience; it occurs as a result of actual or impending tissue damage.
2. Types of pain
a. Fast pain is carried on the A fibers. It is characterized as sharp and acute, and it is elicited by mechanical and/or thermal stimulation.
b. Slow pain is carried on the C fibers and is transmitted at lower velocity than fast pain. It is characterized as burning or aching, or patients may report "suffering." It is elicited by mechanical, thermal, and/or chemical stimulation.
c. Type IVa free nerve endings constitute the articular nociceptive system. The highest concentration of these free nerve endings is found in the quadriceps tendon, with the retinacula and the patellar tendon having the second highest concentrations.
3. Epidemiology
a. Anterior knee pain (AKP; patellofemoral pain) is the most common knee condition in adolescents and young adults.
b. Approximately one third of knee pain symptoms are related to the PF joint.
B. Pathoanatomy
1. To describe the pathoanatomy of AKP (patellofemoral pain) is to suggest that variations in anatomy cause AKP (patellofemoral pain), which is neither completely true nor completely false. AKP (patellofemoral pain) has many possible biologic, mechanical, and emotional causes.
a. Biologic factors associated with AKP (patellofemoral pain) include chemical factors, neuroanatomic and intraosseous vascular abnormalities, and degenerative conditions of articular cartilage (eg, chondromalacia).
i. Chemical factors include substances that stimulate pain, such as histamine, serotonin, and bradykinin, as well as substances that enhance nociceptive stimulation, such as prostaglandins and substance P. Substance P is found in many periarticular tissues including retinacula, synovium, fat pad, and subchondral bone that is affected by degenerative changes.
ii. Neuroanatomic abnormalities include neuromata of the retinacula, as well as peripheral nerve entrapment syndromes (eg, saphenous nerve entrapment).
iii. Intraosseous vascular abnormalities cause elevations in intraosseous pressures (intraosseous hypertension).
iv. Degenerative conditions of the articular cartilage, including chondromalacia, are characterized by softening and fibrillation, and, at times, fragmentation and erosion.
b. Mechanical factors that may be associated with AKP (patellofemoral pain) are those that produce PF malalignment, which is characterized as lower extremity malalignment resulting from a combination of femoral anteversion (medial femoral torsion), external tibial torsion, and/or excessive foot pronation. PF malalignment may also be characterized by lateral subluxation of the patella, lateral tilt of the patella, or a patella that is positioned more proximally (alta) or distally (baja) than normal.
i. This malalignment produces excessive medial rotation of the knee during the stance phase, which, in turn, produces an increased lateral patellar force. Increased lateral patellar force can increase retinacular tension and/or cause lateral patellar subluxation.
ii. With the exception of patella baja, the resulting malalignment generally decreases PF contact areas and thus increases PF joint stress.
iii. Patellar tilt is thought to be caused by a tight lateral retinaculum, but it is more characteristic of VMO dysplasia and/or insufficiency of the medial retinacular restraints.
c. Emotional contributions to AKP (patellofemoral pain)—Studies have shown that depression is a frequent companion to chronic pain, and that patients with AKP (patellofemoral pain) often have more stress-related symptoms and elevated levels of hostility and aggression.
C. Evaluation
1. Evaluation of the patient with AKP (patellofemoral pain) includes a physical examination and plain radiographs. MRI, CT, and bone scintigraphy can also be helpful but they are not routinely required.
2. Physical examination—The physical examination includes a behavioral assessment as well as observational assessments of the patient walking, sitting, and lying supine.
a. A behavioral assessment can help detect emotional factors that may elevate the patient's stress level and enhance perceptions of pain.
b. Observation of gait can help detect abnormal adduction moments and rotations that may contribute to increased PF stress; this examination should include an assessment of foot pronation.
c. Observation of the patient in a sitting position can help detect patella alta, patella baja, and subluxation.
i. Active knee extension and flexion can elicit PF crepitus.
ii. If lateral positioning of the tuberosity in relation to a plumb line dropped from the midpoint of the patella is observed, abnormal lateralization of the tibial tuberosity can be suspected.
d. Observation of the patient in the supine position can help detect patellar mobility and regions of tenderness.
i. Less than one quadrant of passive medial or lateral patellar glide signifies abnormal tightness; medial or lateral glide of more than two quadrants signifies subluxation (three quadrants) or dislocation (four quadrants).
ii. Retinacular tenderness may indicate an area of neuromata.
iii. Quadriceps or PT tenderness may signal inflammation or tendinosis.
iv. The Q angle can be assessed and is considered abnormal if it measures >20° for females and >15° for males.
v. The knee flexion test is positive if the flexed knee (>90°) becomes extremely painful within 30 to 60 seconds; this result suggests intraosseous hypertension.
vi. Although better assessed with the patient in the prone position, the extent of passive internal and external rotation of the hips can reveal femoral malrotation: Internal hip rotation significantly greater than external rotation implies femoral anteversion (or medial femoral torsion). Likewise, an assessment of tibial torsion can be made by recording the transmalleolar axis (normal being 15° to 25° of external rotation).
vii. The detection of joint effusion suggests intraarticular chondral or osteochondral injury.
3. Imaging
a. Plain radiography can detect abnormalities in PF alignment as well as osseous lesions.
i. A true lateral view of the knee can detect most PF alignment abnormalities, including tilt, subluxation, patella alta, and patella baja. In addition, trochlear dysplasia can be assessed accurately.
ii. The Merchant view of the knee has become the most popular axial view on plain radiography; it can detect subluxation and tilt. For this view, the knee is flexed at 45° and the x-ray beam is angled 30°.
b. CT is best for detailing bony anatomy and the tibial tuberosity-trochlear groove distance (as a measure of detecting abnormal lateral positioning of the tuberosity). Normal tibial tuberosity-trochlear groove distance with the knee in extension is 12 mm, with >20 mm being distinctly abnormal. The limitation of CT imaging is that the contour of the articular surface does not always parallel the contour of the subchondral bone; therefore, the assessment of patellar alignment can be misleading.
c. MRI has the advantage of detecting abnormalities of articular cartilage as well as providing a more accurate assessment of joint congruity.
d. Bone scintigraphy—Regions of increased activity imply a loss of bone tissue homeostasis.
D. Classification—AKP (patellofemoral pain) can be either acute or chronic.
1. Acute AKP (patellofemoral pain) is characteristic of acute extensor mechanism overload or traumatic injury. The evaluation should detect the cause.
a. Tenderness may imply patellar or quadriceps tendinitis.
b. The detection of joint effusion suggests intraarticular chondral or osteochondral injury.
c. Peripatellar synovitis is thought to be a common cause of acute and chronic AKP (patellofemoral pain) and is classified as a synovial impingement syndrome.
2. Chronic AKP (chronic patellofemoral pain)
a. AKP (patellofemoral pain) is considered chronic if it has lasted longer than 6 months.
b. Although all pain is accompanied by an emotional component, the patient with chronic AKP (chronic patellofemoral pain) may have a significant psychological history (including childhood emotional trauma).
E. Treatment
1. Nonsurgical—Most often, AKP (patellofemoral pain) is successfully managed with nonsurgical treatment.
a. The general principle of nonsurgical treatment is stress management. This includes reducing mechanical stress to the PF joint, as well as reducing emotional stress.
b. Mechanical stress can be reduced by an appropriate combination of physical therapy and activity modification.
c. Physical therapy should include assessments of myofascial tightness and muscular weakness, as well as assessments of spine, hip, knee, and foot mechanics.
i. The importance of the strength of the VMO has been overemphasized. A more current understanding of the important role that pelvic stabilizers play in relation to gait has resulted in programs that emphasize core stability.
ii. Painful exercises reinforce the hypersensitization of the nociceptive system; therefore, all exercises should be performed in a non-painful manner.
iii. Knee orthoses and/or taping techniques may reduce PF stress by improving alignment and increasing PF contact area.
iv. Activity modifications should include an emphasis on low-impact aerobic activities and aquatic exercise.
d. Nutritional counseling should be provided for overweight individuals.
e. Emotional stress can be managed most often by reassuring the patient that AKP (patellofemoral pain) is nondestructive. However, patients with chronic AKP (chronic patellofemoral pain) may benefit from psychological counseling.
2. Surgical
a. Surgical treatment of AKP (patellofemoral pain) is a slippery slope.
b. Surgery is indicated for patellar instability and pain. Patients with patellar instability and pain, in whom instability is the primary symptom and pain is secondary to the instability, often have the most consistent surgical results.
c. The relationship between PF malalignment and pain is inconsistent. One cannot assume that malalignment is the cause of the AKP (patellofemoral pain). Just as chondromalacia of the patella may or may not be associated with AKP (patellofemoral pain), PF malalignment may or may not be associated with pain.
d. Surgical procedures
i. Lateral retinacular release is indicated for the relief of AKP (patellofemoral pain) when the lateral retinaculum is tight. Lateral retinaculum tightness can be determined during the physical examination.
ii. Tibial tuberosity transfer results in load transfer and not necessarily load reduction. An understanding of where the patellar chondral injury is located is important. Medialization of the tibial tuberosity shifts the load to the medial facet. Anteriorization of the tibial tuberosity shifts the PF loading proximally on the patella, whereas anteromedialization shifts patellar load proximally and medially.
iii. Restoration of the articular cartilage of the PF joint has traditionally produced inconsistent results.
iv. Resection of inflamed peripatellar synovial tissue (plica syndrome, synovial impingement syndrome, fat pad syndrome) may do no harm, but clinical results remain at the testimonial level (case series).
III. Rupture of the Patellar Tendon or Quadriceps Tendon
A. Overview/epidemiology
1. Rupture of the patellar tendon or quadriceps tendon generally occurs with eccentric loading of the knee extensor mechanism, often when the foot is planted and the knee is slightly bent.
2. Less commonly, these injuries can occur with a direct blow to the tendon when the extensor mechanism is under tension.
3. Rupture of the patellar tendon is most common in patients younger than age 40 years.
4. Rupture of the quadriceps tendon is most common in patients older than age 40 years.
5. Patients who sustain quadriceps tendon ruptures may have underlying conditions that predispose them to injury, such as obesity, diabetes mellitus, hyperparathyroidism, rheumatoid arthritis, systemic lupus erythematosus, hyperbetalipoproteinemia, hemangioendothelioma, chronic renal failure, or gout.
6. Anabolic steroid use and local corticosteroid injection into the tendon are also associated with both types of tendon ruptures.
B. Pathoanatomy
1. Both patellar tendon and quadriceps tendon ruptures typically occur at the tendon attachment to the patella.
2. Underlying chronic degeneration is often present and is characterized by angiofibroblastic tendinosis, mucoid degeneration, and pseudocyst formation at the attachment of tendon to bone.
3. The quadriceps tendon has been described as having from two to four distinct layers. This is important when distinguishing between partial versus complete ruptures and when repairing the tendon.
C. Evaluation
1. History
a. Patients with a rupture of the patellar tendon or quadriceps tendon often report a history of pain, which is consistent with the presence of underlying tendon degeneration.
b. Patellar tendon rupture also has been reported after central-third tendon harvest for knee ligament reconstruction.
c. The rupture typically occurs during an eccentric load on a flexed knee, such as a landing from a jump or taking a forceful step while descending stairs. Less commonly, a rupture can occur during a forceful quadriceps contraction when taking off for a jump.
2. Physical examination
a. Physical examination for a complete rupture of either the patellar tendon or the quadriceps tendon demonstrates tenderness at the site of the injury, hematoma, and a palpable defect in the tendon.
b. Patients with a complete rupture of either tendon are unable to extend the knee against resistance or to perform a straight-leg raise.
3. Imaging
a. Radiographs
i. Radiographs of the knee after patellar tendon rupture demonstrate patella alta, particularly when the radiograph is taken with the knee flexed.
ii. Radiographs after quadriceps tendon rupture demonstrate patella baja and will sometimes show bony fragments in the region of the rupture.
b. Magnetic resonance imaging—MRI can be helpful when there is uncertainty regarding the diagnosis, particularly when trying to differentiate between partial and complete rupture of a tendon.
D. Classification—A rupture is classified according to its severity (either partial or complete) and its location (patellar tendon or quadriceps).
E. Treatment
1. Nonsurgical
a. Nonsurgical treatment is indicated for partial rupture of the patellar or quadriceps tendon when there is no disruption of the extensor mechanism. It is also indicated for patients who are unable to tolerate surgery because of poor overall medical condition.
b. Nonsurgical treatment consists of an initial period of immobilization in a knee brace, followed by progressive range-of-motion and strengthening exercises beginning approximately 6 weeks after injury.
2. Surgical
a. Surgery is generally indicated for a complete rupture of the patellar or quadriceps tendon.
b. Early surgery (within the first 2 weeks after injury) is recommended, so tissues do not have an opportunity to scar down in a retracted position.
3. Surgical procedures
a. Patellar tendon rupture repair
i. This procedure is performed through a mid-line incision.
ii. Nonabsorbable sutures are placed in the tendon using a running locking stitch and passed through longitudinal drill holes in the patella.
iii. The retinaculum is repaired with a heavy absorbable suture, and the paratenon is repaired if possible.
iv. Intraoperative fluoroscopy or radiographs with comparison to the contralateral knee can be used to judge appropriate tendon length. Ideally, the knee should flex to 90° after repair.
b. Quadriceps tendon repair
i. Like patellar tendon repair, quadriceps tendon repair is also performed through a mid-line incision.
ii. Longitudinal drill holes are placed in the patella, the tendon is sutured using a heavy nonabsorbable suture in a running, locking fashion, and the tendon is secured to bone.
iii. The retinaculum is then sutured using a heavy absorbable suture.
iv. If necessary, reinforcement is carried out using a quadriceps turndown method, a pull-out wire, or a fascia lata or hamstrings autograft.
v. Ideally, the knee should flex to 90° after repair.
4. Complications
a. Patellar tendon rupture repair—Repair of chronic patellar tendon rupture can be complicated by proximal retraction of the patella and by insufficient tissue for repair. Retraction can be addressed by surgical dissection and mobilization of the quadriceps tendon.
i. Tendon augmentation can be performed with a hamstring autograft passed through tibial and patellar drill holes, a central quadriceps tendon-patellar bone autograft, a contralateral bone-patellar tendon-bone autograft, or an allograft.
ii. Augmentation with wire, nonabsorbable tape, or heavy suture also can be considered.
b. Quadriceps tendon rupture repair—Similar to chronic patellar tendon ruptures, chronic quadriceps tendon ruptures can be complicated by proximal migration of the tendon stump, which requires debridement and mobilization of the tendon. Once this has been achieved, the tendon can be augmented with autograft or allograft tissue and secured to bone.
F. Physical therapy/rehabilitation
1. Patellar tendon rupture repair—Postoperatively, the patient may bear weight, but the limb should initially be protected in a cylinder cast or a brace. Progressive range-of-motion and strengthening exercises are commenced in the weeks following surgery.
2. Quadriceps tendon rupture repair (acute or chronic)—Postoperative care involves a period of immobilization in a cylinder cast or splint followed by progressive flexibility and strengthening exercises.
IV. Patellar or Quadriceps Tendinopathy
A. Overview/epidemiology
1. Patellar or quadriceps tendinopathy occurs in active individuals who engage in activities that involve forceful, eccentric contraction of the knee extensor mechanism, particularly jumping sports.
2. Harder playing surfaces and increased frequency of practices have been associated with increased rates of tendinopathy.
3. Patellar tendinopathy, or jumper's knee, occurs most frequently in adolescents and young adults, whereas quadriceps tendinopathy occurs in middle-aged and older people.
B. Pathoanatomy
1. Patellar tendinopathy tends to occur at the patellar attachment of the tendon, in the deep fibers.
a. This area has a tenuous blood supply, and affected tissue may demonstrate fibrinoid necrosis or angiofibroblastic change or mucoid degeneration and disorganized collagen structure. In addition, metaplasia of adjacent fibrocartilage may be present.
b. The medial portion of the patellar tendon often demonstrates thickening compared with the rest of the tendon.
2. The pathoanatomy of quadriceps tendinopathy is similar to that of patellar tendinopathy.
C. Evaluation
1. History
a. Patients with patellar or quadriceps tendinopathy describe an insidious onset of pain and swelling of the affected tendon.
b. These symptoms initially develop after activity, gradually start to bother the individual both during and after activity, and eventually limit athletic performance during the activity.
c. Patients also may report buckling of the knee, which represents reflex quadriceps inhibition due to pain.
2. Physical examination
a. Physical examination reveals tenderness and soft-tissue swelling, usually in the area where the tendon attaches to the patellar bone.
b. Patients often have discomfort with resisted extension of the knee.
3. Imaging
a. Plain radiographs of the knee may demonstrate degenerative spurring where the affected tendon attaches to bone.
b. MRI usually shows thickening in the affected portion of the tendon. It also may demonstrate intrasubstance signal abnormalities, but thickening is much more diagnostic than signal changes when identifying abnormal tendon on MRI.
D. Classification—The three stages of tendinopathy, according to Blazina, are listed in
Table 1.
[Table 1. Blazina Classification of Patellar or Quadriceps Tendinopathy]
E. Treatment
1. Nonsurgical intervention is the mainstay of treatment for patellar and quadriceps tendinopathy.
a. Initial treatment consists of activity modification, rarely including immobilization, until symptoms subside.
b. This is followed by progressive flexibility and eccentric strengthening exercises until the individual can return to the desired level of activity without pain.
c. Taping to aid proprioception and patellar tracking or use of an infrapatellar strap can be helpful in some cases.
d. Nonsteroidal anti-inflammatory drugs also can be beneficial.
e. Corticosteroid injection is contraindicated because of the increased risk of tendon rupture.
2. Surgical treatment is reserved for patients who continue to have pain and swelling of the tendon after attempting an acceptable nonsurgical treatment regimen.
3. Surgical procedures are performed according to the surgeon's preference.
a. Options include various methods of debriding diseased tissue and stimulating a vigorous healing response.
i. This can be achieved by simple longitudinal excision of the diseased portion of tendon, followed by abrasion of the bone to provide a bleeding surface for tendon healing, and finishing with the application of side-to-side sutures or suture anchors as needed.
ii. Variations of this procedure include drilling of the bone to stimulate a healing response or multiple tenotomy to stimulate healing of the tendon tissue.
b. All procedures can be performed using a standard anterior midline incision to expose the diseased tendon and its attachment to the patella.
Top Testing Facts
Lateral Patellar Dislocation
1. The medial patellofemoral ligament (MPFL) is the main passive restraint to lateral translation of the patella; it is torn in lateral patellar dislocations.
2. Nonsurgical management is the cornerstone of treatment for first-time patellar dislocation.
3. Osteochondral loose bodies and recurrent dislocation after physical therapy are indications for surgical treatment of lateral patellar dislocation.
4. Medial dislocation of the patella is almost exclusively a result of prior surgery.
Anterior Knee Pain (Patellofemoral Pain)
1. The detection of joint effusion in conjunction with AKP (patellofemoral pain) suggests intra-articular chondral or osteochondral injuries.
2. AKP (patellofemoral pain) is usually managed successfully with nonsurgical treatment. Physical therapy includes assessments of spine, hip, knee, and foot mechanics.
3. Lateral retinacular release is indicated for relief of AKP (patellofemoral pain) when the lateral retinaculum is tight.
Rupture of the Patellar Tendon or Quadriceps Tendon
1. Rupture of the patellar tendon is most common in patients younger than age 40 years, whereas rupture of the quadriceps tendon is most common in patients older than age 40 years.
2. Patellar or quadriceps tendon rupture occurs during eccentric loading of the knee extensor mechanism and is usually associated with predisposing factors.
3. Nonsurgical treatment is indicated for partial rupture of the patellar or quadriceps tendon when there is no disruption of the quadriceps mechanism.
4. Surgery is generally indicated for a complete tendon rupture.
Patellar or Quadriceps Tendinopathy
1. Patellar or quadriceps tendinopathy is characterized by disorganized collagen structure visualized on MRI by thickening of the tendon and signal changes.
2. Nonsurgical intervention is the mainstay of treatment. Corticosteroid injection is not recommended because it increases the risk of tendon rupture.
Bibliography
Canale ST, Campbell WC (eds): Campbell's Operative Orthopaedics, ed 10. St. Louis, MO, Mosby, 2003.
DeLee J, Drez D, Miller MD: DeLee & Drez's Orthopaedic Sports Medicine: Principles and Practice, ed 2. Philadelphia, PA, Saunders, 2003.
Garrick JG (ed): Orthopaedic Knowledge Update: Sports Medicine, ed 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004.