Journal of Orthopaedic & Sports Physical Therapy 2OOO;3O (3) : 138-1 42 Diagnosis of Patellofemoral Pain After Arthroscopic Meniscectomy Karen Muller, MPT1 Lynn Snyder-Mackler, ScD, P7; SCS2 Journal of Orthopaedic & Sports Physical Therapy BACKGROUND Anterior knee pain is a common complaint, occurring in approximately 1 of 4 people; individuals involved in athletics report an even higher incidence.' The condition is more common in women than men and most often affects younger persons, with a peak incidence between the ages of 10 and 35 years. Symptoms include the following: pain in the knee when ascending and descending stairs, when squatting, or with prolonged sitting; swelling; a popping or grinding sensation; and incidences of the knee buckling or giving ~ay."~j~ Often termed patellofernota1 pain syndrome (PFPS), the spectrum of symptoms varies greatly from one individual to another (eg, achy pain after a long run or severe pain when rising from a chair). Many patients with anterior knee pain are eventually referred to rehabilitation. Although PFPS is one of the most common clinical conditions treated by orthopaedic and sports physical therapists, a consensus as to how these patients should be managed does not exist. Subtle variations in symptoms (and the attribution of symptoms to a variety of different causes) deem it unlikely that a generic protocol for treatment or exercise prescription can be developed for the entire scope of individuals experiencing PFPS. Differential diagnosis must consider a range of inflammatory conditions, mechanical problems, and other conditions (eg, tendinitis and bursitis, patellar hypermobility, subluxation and dislocation, posterior cruciate ligament tear, plica, loose bodies, reflex sympathetic dystrophy, osteochondritis dissecans, systemic arthritis, muscle strain, stress frac- Spom physical therapy resident, Department of Physical Therapy, University of Delaware, Newark, Del. Associate professor, Department of Physical Therapy, University of Delaware, Newark, Del. Send correspondence to Lynn Snyder-Mackler, Department of Physical Therapy, 053 McKinly Lab, University of Delaware, Newark, DE 19716. E-mail: smack@udel.edu ture, meniscal tear, neuroma, tumor, and iliotibial band syndrome).5"j4 When examining subjects with PFPS, clinicians have observed all the following symptoms: quadriceps weakness, excessive forefoot pronation, limb length discrepancy, increased Q angle, patella alta, iliotibial band, vastus lateralis and lateral retinacular tightness, excessive genu recurvaturn, and patellar instability. These factors are hypothesized to affect the alignment of the patellofemoral joint. Dysplasia of the oblique fibers of the vastus medialis has been implicated in the development of aberrant direction of the effective quadriceps pull on the at el la:^ Lateral tracking of the patella can result in excessive compression between the patellar facets and the femoral gr~ove.~j This malalignment may provoke irritation or inflammation of the soft tissue structures about the joint. Identifying the origin of the irritation or inflammation may be critical for developing a treatment that will result in prompt resolution of symptoms. Wilk et a1 proposed a classification system, based on an individual's signs and symptoms, that can be used as a foundation for treatment strategies and interventions for the nonoperative management of patients with PFPS. This system divides patellofemoral disorders into 8 groups as outlined in table 1 of the article by Wilk et al.14 Trauma to the knee, including surgery, can also cause inflammation and mechanical problems associated with PFPS. Postoperatively, patients may develop symptoms consistent with PFPS even after knee ligament or meniscal surgery. Failure of voluntary activation of the quadriceps can occur as a result of an acute effusion and have a deleterious effect on the extensor mechanism. This will also result in irritation or inflammation around the patellofemoral joint. Clinicians must recognize the patient's complaints as PFPS rather than simply attributing the pain to surgery itself. Patellofemoral pain can be the primary diagnosis for patients after knee surgery.
A variety of techniques have been advocated for treatment of PFPS. Some of these techniques include nonsteroidal anti-inflammatory drugs, ice, quadriceps strengthening, stretching, patella taping or bracing, and orthotics-%'j1j4; however, if we simply treat the inflammatory process without treating the underlying cause, the condition will ultimately become chronic or recurrent. Conversely, if we attempt to treat the malalignment without addressing the inflammatory process first, a chronic complaint of pain may result. Any exercise or technique that recreates pain might perpetuate inflammation. A technique that works in one instance may not work in another. The chronicity of the disorder, level of pain and inflammation, activity level, and lower extremity alignment should all be considered when developing a management strategy. Treatment and exercise programs must be based on specific signs and symptoms of each individua1.5.hj1j4 The purpose of this report, therefore, is to illustrate the diagnostic process in the development of a treatment plan for a patient with anterior knee pain after meniscal surgery. HISTORY The patient is a 52-yeardd state police officer who was referred to physical therapy 2 months after arthroscopic debridement of his left knee with knee pain. Operatively, he had meniscal degeneration, some fibrillation of the articular cartilage on the medial side, and medial osteoarthritis. The patient's major symptom before surgery was medial knee pain, which resolved after surgery. After surgery, he developed symptoms of anterior knee pain while ascending and descending stairs, walking on the beach, jogging, and squatting. The patient continued working, because he had a desk assignment. The anterior knee pain now prevented him from golfing and jogging. The patient had received an injection of lidocaine and dexamethasone to his left knee 9 days before his physical therapy evaluation, decreasing his pain enough to allow him to return to playing golf. He was also taking an oral nonsteroidal anti-inflammatory drug. His goal was to return to jogging without pain. Differential Diagnosis Based on History and Symptom Behavior The patient had significant relief of his symptoms from the steroid injection, suggesting that an inflammatory process was involved. His pain and symptoms were different from those he had before surgery. His symptoms of anterior knee pain when ascending stairs, descending stairs, and squatting were consistent with those of PFPS. It is possible that the patient experienced quadriceps weakness from his previous injury or surgery. Weakness of the extensor mechanism could be the cause of the irritation about the patella. His symptoms focused our evaluation on the patellofemoral region. PHYSICAL EXAMINATION General observation revealed visible atrophy to the left quadriceps with vastus medialis dysplasia, 1 + joint effusion (swelling can be milked out and does not return until it is swept back down), and wellhealed portal scars. Patellar mobility was decreased medially, laterally, and superiorly compared with the opposite side. A verbal pain scale of 0-10 was used during palpation, with 0 representing absence of pain and 10 representing the worst pain imaginable. Palpation of the peripatellar region on the right did not produce pain. Pain was produced on palpation of the left patellar tendon (3-4/10), lateral patellofemoral ligament (1-2/ lo), and quadriceps tendon (3-WlO). Both lower extremities demonstrated generalized decreased flexibility. Range of motion was measured using a universal goniometer. Active and passive knee extension was measured in long sitting with the heel propped on a wedge (-2" with active quad set and 0" statically for the left side and 0" with active quad set and 2" statically for the right side). Active knee flexion was measured in prone (135" left and 131" right). Hamstring tightness was assessed in supine with a passive straight leg raise (65" left and 58" right). Gastrocnemius flexibility was also tested in long sitting with passive dorsiflexion of the ankle (5" left and 8" right). Rectus femoris tightness was assessed in a modified Thomas test position? with the thigh dangling off the end of the table, and the angle of passive knee flexion was measured (45" left and 60" right). Iliotibial band tightness was assessed using an Ober test? the results of which were positive bilaterally. Manual muscle testing grades were 4 of 5 for the quadriceps and hamstrings on the left and 5 of 5 for the quadriceps and hamstrings on the right. Because, with a stronger individual, it is difficult to determine how large a deficit a grade of 4 of 5 on the manual muscle test is, we decided that testing with an instrument was needed. Further strength testing was performed using an electromechanical dynamometer to test maximal volitional isometric contraction of the quadriceps at 60" of knee flexion. The left quadriceps maximal volitional isometric contraction was 20% less than the right quadriceps. Provocative testing was performed using a stepup test. Pain grades and the angle of the knee when pain occurred were recorded. Patellar taping (medial glide then superomedial glide) was used serially to assess effect of medial glide on the results of the step test (Figure 1A and B). The patient reported pain J Orthop Sports Php Ther-Volume 30. Number 3. March 2000
1 FIGURE 1. Step test (A) with the patella taped (B). levels of 7 of 10 at 52" of knee flexion, stepping onto a 10-in step. Medial taping decreased his symptoms to 5 of 10, and the pain did not begin until 70" of knee flexion. Addition of superomedial taping further decreased his symptoms to 0-1 of 10 at 70". - Differential Diagnosis Based on Results of Physical Examination The flexibility of the rectus femoris, hamstring, iliotibial band, and gastrocnemius was not dramatically different from one side to the other. This suggests that flexibility was not a significant factor causing pain symptoms. The evaluation also indicated deficits in strength of the left quadriceps and vastus medialis dysplasia and decreased patellar mobility. Weakness and patellar hypomobility may have increased stress on the patellofemoral joint, causing pain and inflammation. The step-up test produced the most pain and provided a maneuver for evaluating treatment effectiveness. Patellar taping dramatically decreased the pain during step-up, suggesting that addressing the weakness and patellar mobility should improve the patient's symptoms and function. TREATMENT Treatment addressed each of the impairments found during the evaluation. High-intensity electrical stimulation, burst-modulated alternating current, and ice were used for reduction of pain.12 The burst-modulated alternating current consisted of a 2500-Hz sine wave at a 50% duty cycle. Fifty bursts per second (2-second ramp) for 12 seconds (includes ramp) followed by 8 seconds of rest were applied for 10 minutes. The stimulation was applied by preparing the area directly over the painful sites of the quadriceps and patellar tendons with alcohol, after which each site was bounded by small electrodes (approximately 1 X 2 cm) (Figure 2). The intensity of the current was slowly increased as high as was tolerable for the patient.12 The quadriceps tendon was treated for 2 sessions and the patella tendon for only the first session, after which the pain to palpation had resolved. Bilateral stretching exercises for the quadriceps, hamstrings, gastrocnemius, and iliotibial band were incorporated into a home exercise program. Patella hypomobility was treated both actively and passively. Superior patella glides were achieved actively by performing quadriceps sets and other active quadriceps J Orthop Sports Phys Ther-Volume 30. Number 39 March 2000
FIGURE 2. Set-up for high-intensity electrical stimulation. exercises. Medial patella mobility was treated using passive medial gliding of the patella to stretch the lateral soft tissue structures. The therapist performed grades I11 and IV glides,1 and the patient was taught to perform the glides as part of his home exercise program. Patellar taping was used during performance of strengthening exercises. After 2 sessions, the tape was no longer needed for pain control, and his strengthening exercises progressed: repetitions were increased from 2 X 10 to 2 X 12, step height was increased from 4 to 6 in, and treadmill jogging was initiated. The patient began jogging 1 week after his initial treatment and returned to the clinic for 2 more visits to monitor his response to the progression of jogging activities and exercise program. The patient was discharged after a total of 6 visits with no complaints of pain during the performance of activities of daily living. He had the ability to jog for 10 minutes without symptoms. He was instructed to continue his stretching and strengthening program independently at home. DISCUSSION This patient's symptoms were quickly and easily relieved by directing treatment at specific impairments and pain identified by palpation of soft tissue structures and provocative stepup testing. Although our initial hypothesis strongly emphasized the effect of quadriceps weakness on the patellofemoral joint, in retrospect, the pain control treatment had an immediate effect on quadriceps muscle performance. Consequently, the measured weakness was most likely caused by local inflammation, resulting in pain provoked during a c~ntraction.~.~ The inflammation and pain were addressed by using high-intensity electrical stimulation. This is an uncomfortable modality for the patient, but there a p pears to be a positive dose-response relationship.12 There should be immediate and long-lasting symptomatic relief, which gives the patient motivation to withstand the procedure. Preliminary research on this modality indicates that the reduction in pain levels can be linked to immediate improvement in quadriceps muscle performance. Not only is this significant in the treatment of patellofemoral pain, for which quadriceps function is a critical component to recovery, but to any other condition in which pain and muscle function are linked.1.2.4j2 Increasing patellar mobility also decreased the patient's pain symp toms. Again, improvement in symptoms (a reduction of pain and weakness) was too rapid to be the result of improved medial patellar mobility; however, improved active superior mobility can occur rapidly and would theoretically increase measured quadriceps strength by allowing optimal tracking of the knee extensor mechanism. In this patient's case, there was complete relief of pain symptoms after 2 treatments that resulted in marked improvement in quadriceps function as exhibited by swift progression of strengthening exercises. In conjunction with the noxious stimulation and increased patella mobility, patellar taping also allowed the patient to begin performing strengthening exercises without pain and irritation. Once the patient's pain and quadriceps inhibition were resolved, he no longer needed taping intervention and was able to progress his strengthening exercises to achieve his goal of jogging pain free. Quadriceps strengthening was performed using exercises that are completely pain free to avoid exacerbating the patient's symptoms. In this specific case, the weakness recorded during evaluation was most likely secondary to quadriceps inhibition from pain rather than substantial weakness of the muscle itself. The patient was able to rapidly progress his exercise program once this pain and inhibition cycle was broken. In situations where true weakness exists, the strengthening progression will take place in a more gradual, stepwise fashion. Patients' exercise programs, therefore, must be individually tailored to their present abilities and their long-term goals.3.6,1 1.14 Clearly, not all patients with anterior knee pain will present with the same symptoms. The approach to treatment should address identified impairments and relate them to function. Similar treatment principles can be applied to patients with anterior knee pain that results from overuse or structural proh lems, traumatic injuries, and surgical interventions. Patients who have knee surgery will have muscle weakness, inhibition, or both and lack of joint mobility that can result in patellofemoral pain syndrome as previously described. Their complaints should not be dismissed as related to the preoperative condition. It is important to systematically evaluate and reevaluate patients, following up with a treatment that is specifically directed by findings. This process might shorten J Orthop Sports Phys There Volume SO. Number 3. March 2000
episodes of care and increase patient satisfaction with physical therapy. REFERENCES 1. Arvidsson I, Eriksson E. Post operative TENS pain relief after knee surgery: objective evaluation. Orthopedics. 1986;9:1346-1351. 2. Arvidsson I, Eriksson El Knutsson E, Arner S. Reduction of pain inhibition on voluntary muscle activation by epidural analgesia. Orthopedics. 1986;9:1415-1419. 3. Brody LT, Thein JM. Nonoperative treatment for patellofemoral pain. J Orthop Sports Phys Ther. l998;28:336-344. 4. Eriksson E. Rehabilitation of muscle function after sports injury. Int) Sports Med. l982;2:1-6. 5. Fu FH, Stone DA. Sports Injuries. Baltimore, Md: Williams & Wilkins; 1994. 6. Grelsamer RP, McConnell J. The ktella. Gaithersburg, Md: Aspen Publishers Inc; 1998. 7. Laprade J, Culham E, Brouwer B. Comparison of five iso- metric exercises in the recruitment of the vastus medialis oblique in persons with and without patellofemoral pain syndrome. 1 Orthop Sports Phys Ther. 1998;27:197-204. 8. Loudon JK, Goist HL, Loudon KL. Genu recurvatum syndrome. 1 Orthop Sports Phys 7her. 1998;27:361-367. 9. Magee DJ. Orthopedic Physical Assessment. 3rd ed. Philadelphia, Pa: WB Saunders Co; 1997:482483. 10. Maitland GD. Peripheral Manipulation. 3rd ed. London, England: Butterworth-Heinmann; 1991. 11. Malone TR, McPoil TI Nitz AJ. Orthopedic and Sports Physical Therapy. 3rd ed. St Louis, Mo: Mosby Publishers; 1997. 12. Manal TJ, Snyder-Mackler L. Electrotherapy for pain management. Rehabil Manage. JundJuly 1996:56, 62. 13. Powers CM, Landel R, Sosnick T, et al. The effects of patellar taping on stride characteristics and joint motion in subjects with patellofemoral pain. ) Orthop Sports Phys Ther. 1 997;26:286-291. 14. Wilk KE, Davies GJ, Mangine RE, Malone TR. Patellofemoral disorders: a classification system and clinical guidelines for nonoperative rehabilitation. ) Orthop Sports Phys Ther. 1998;28:307-322. Journal of Orthopaedic & Sports Physical Therapy J Orthop Sports Phys Ther.Volume 50. Number 3. March 2000