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Case Reports |
MP Johnson, PT, MS, OCS, is Director of Professional Development, Mercy Rehab Associates, 1503 Lansdowne Ave, Darby, PA 19023 (USA) (mjohnson1{at}mercyhealth.org)
Submitted September 7, 2003;
Accepted December 13, 2004
 | Abstract |
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Key Words: Cartilage diseases • Clinical decision making • Connective tissue • Iontophoresis • Knee injuries
| Introduction |
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Osteochondritis dissecans can occur at many joint articulations; however, it is most common in the femoral condyles, talar dome, and capitellum.3,7 The femoral condyles are the site for 75% of the lesions.9 The incidence of OCD of the knee is 3 to 6 out of every 10,000 people.10 It occurs most often between the ages of 10 and 20 years and is twice as common in males as in females.10,11
Osteochondritis dissecans at the knee can occur along the inferior surface of the patella, the lateral femoral condyle, or, most commonly, along the medial femoral condyle. Location on the medial condyle accounts for approximately 75% to 85% of all femoral lesions.3,8 These lesions are typically located along the lateral aspect of the medial condyle within the intercondylar groove11; however, they can extend more medially along the weight-bearing surface of the condyle (Fig. 1). Lesions on the medial femoral condyle tend to be located more anteriorly compared with those on the lateral condyle.12,13 Hughston et al13 used a lateral radiograph of the knee to examine anterior or posterior positioning of OCD lesions. They characterized lesions as: (1) located directly distal to a line drawn parallel to the posterior cortex of the femur or (2) lying posterior to that line. The location of the lesion determined when during the knee range of motion (ROM) it was engaged by the tibia (Fig. 2).
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Patients in categories I and II were considered skeletally immature, generally having open epiphyseal plates resulting in continued musculoskeletal growth. Patients in category III were considered skeletally mature, with closed epiphyseal plates. Pappas3 and other authors8,9,12,20 contended that the prognosis for healing of symptomatic lesions in adult, skeletally mature patients (>20 years of age) without the assistance of surgical intervention is poor. Hinshaw et al9 suggested that symptomatic OCD lesions on the femoral condyles most often require surgery in adult patients to promote healing. In a multicenter, retrospective study, Hefti et al8 found improvements in knee outcomes after both conservative and surgical management with patients who still had an open epiphysis compared with those who were skeletally mature.
Conservative management for juvenile and adult patients with stable lesions may consist of: (1) non–weight bearing for 6 to 8 weeks,5,20 followed by restricted sports and other activities for 6 weeks5,7,20,21; (2) knee immobilization5; (3) daily ROM exercises5; and (4) isometric strengthening exercises.5 A return to normal activities is advocated only after clinical and diagnostic (MRI, radiograph) evidence indicates that the lesion has healed.5 I found only 2 articles5,8 that listed interventions used in the conservative management of adult patients with stable lesions. Few of the interventions listed, however, included details necessary for use in patient management.
Although the age of the patient and stability of the lesion are considered important prognostic variables, other factors need to be taken into account, such as the size22 and location8,11,12 of the lesion, when making the clinical decision about how to effectively manage an adult patient with OCD of the knee. In addition to age, Hefti et al8 found better outcomes with conservative management on follow-up examination (mean=4 years after intervention, range=1–20 years) in patients (n=79) who had "favorable" conditions at the knee during initial examination. According to Hefti et al, "favorable" conditions include all 3 of the following findings: (1) no to moderate joint effusion, (2) fragment diameter 
20 mm, and (3) no gross dissection (instability) of the lesion seen with diagnostic imaging. The sample in this study consisted primarily of children (mean age=13 years 3 months). Some of those receiving conservative management (n=154) who had "favorable" conditions at the knee, however, were adults, as defined by a closed epiphysis.
Conservative management of adult patients (>20 years) with OCD of the knee is rarely recommended in the literature.3,5,9,20 Evidence suggests, however, that some adult patients with OCD may benefit from physical therapist management. The purpose of this case report is to describe and discuss the examination, evaluation, and decisions related to physical therapist management of an adult with OCD at the tibiofemoral joint.
| Case Description |
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The patient reported that, before the onset of symptoms, she was able to work a 12-hour shift and walk recreationally 3.2 to 4.8 km (2–3 miles) an average of 3 to 4 days a week. At the time of the initial physical therapy visit, she said she could work a maximum of 8 hours and was unable to walk regularly for exercise because of continued right knee pain. She also said that she was unable to go up or down stairs, kneel on the front of her knee, sit for more than 20 minutes, or drive a car without an increase in pain. The Single Assessment Numeric Evaluation (SANE)23 was used to assess function of her knee, which she rated as 55% of normal. The SANE is a self-report measure that requires the patient to rate the present level of function on a numeric scale from 0 to 100 (100=normal function). The score represents a simple, quantitative outcome measure that captures the patient's own perception of function. This scale has been validated against a modified Lysholm knee score,24 a functional questionnaire that incorporates a numeric activity score (r=.58–.87).
The patient described her symptoms as general aching along the anteromedial aspect of the right knee. The knee was pain-free in the morning, but her symptoms slowly increased throughout the day. Rest (non–weight bearing) and the use of ice were effective for temporarily decreasing and controlling knee pain. At the time of the initial examination, she stated that her pain was 1 out of 10 on an 11-point numeric rating scale (NRS) (0="no pain" and 10="the most excruciating pain you have ever felt").25 She reported that her knee pain increased to 10 during prolonged standing and walking, especially by the end of her work shift. The test-retest reliability (Pearson r) of the 11-point NRS for pain has been estimated to be .67 to .96.26 Von Korff et al25 reviewed literature related to the use of this NRS in patients with acute, chronic, and postoperative pain and concluded that it has acceptable validity and sensitivity to change.
The patient reported a medical history that included a previous episode of right knee pain (approximately 5–6 years earlier) that resolved without medical intervention, migraine headaches, polycystic ovary disease, cardiovascular hypertension, von Willenbrand disease (a common hereditary bleeding disorder with predominantly mild clinical symptoms), and a family history of OCD (sister). She said she took 3 prescription medications before her course of physical therapy: Accupril* to decrease blood pressure, Celebrex for pain and inflammation, and Loestrin* for birth control.
The patient did not smoke or drink and planned to be married in 2 months. Her goals for therapy included: (1) avoiding surgery, (2) returning to work at full capacity with minimal knee pain, and (3) walking down the aisle at her wedding with no knee pain wearing high-heeled shoes. She was particularly concerned about not losing any further work time because of a need to save money for her upcoming wedding.
Examination
Observation.
The patient had an endomorphic body type and reported that she was approximately 30 lb (13.5 kg) over her normal weight and had been so for more than 1 year. No lower-extremity bony alignment abnormalities were noted. No joint swelling or effusion was observed in either knee.
Range of motion.
Passive and active knee flexion and extension, measured with the patient in a supine position, were within normal limits bilaterally.27 Pain was reproduced with end-range overpressure during both extension and flexion testing of the right knee. The patient reported greater pain with passive knee extension than flexion.
Muscle performance.
Manual muscle testing was performed in accordance with the manual muscle testing procedures described by Kendall et al.28 The patient's quadriceps femoris and hamstring muscles were rated "Normal" for the left knee. Both muscles were rated "Fair" for the right knee. She reported anterior joint pain during resistance testing of the right knee, but did not describe pain arising from the tendon or muscle bellies of the quadriceps femoris and hamstring muscles on the right leg. It was plausible that her inability or unwillingness to generate normal contractile force was the result of pain rather than of the presence of true muscle weakness.
Muscle length testing also was performed according to procedures described by Kendall et al.28 Testing revealed no length restrictions of the quadriceps femoris, hamstring, tensor fasciae latae/iliotibial band, gastrocnemius, or soleus muscles in either lower extremity. This finding suggested that limitations in muscle length were not contributing to abnormal forces or loads at the lower extremity during activity. Although some information about muscle length can be inferred from a ROM assessment (ie, hip adduction and tensor fasciae latae/iliotibial band), this assessment cannot provide information about the length of the hamstring muscles, for example. In addition, proper examination of muscle length requires standardized testing methods that are not equivalent to those used for ROM measures.
Special tests.
All special tests were performed as described by Magee.29 The patient demonstrated no abnormalities with neurological testing, including sensory, dermatome, and myotome screening exams.
Ligamentous stability tests were performed on both knees. Varus and valgus stress tests performed at 0 degrees and 30 degrees were negative. Lachman and anterior and posterior drawer tests revealed no apparent cruciate ligament insufficiencies. Meniscal integrity was not tested during the examination because the patient reported increased pain when initially attempting either the McMurray or Apley compression tests. The patellar grind test, however, caused no increased pain.
Gait.
The patient's gait pattern suggested a painful right lower extremity. Observed deviations from normal included decreased stance time and heel-strike and limited knee ROM during the swing phase. The patient avoided full knee extension during swing, which limited heel-strike.30
Palpation.
Palpation was performed with the knee flexed at 45 degrees to expose the area where the lesion was located according to the MRI report. She reported mild tenderness along the medial femoral condyle on the left knee (rated as 2/10 pain), but more point tenderness was noted with direct palpation to the inferocentral medial femoral condyle on the right knee (rated as 8/10 pain). She reported no specific tenderness with palpation along the joint line medially, laterally, or posteriorly on the right knee.
Evaluation
The key examination findings included decreased tolerance to weight bearing activities, stance time, and terminal knee extension during gait, as well as increased pain with passive overpressure into knee extension and palpation along the anteromedial right femoral condyle. These findings led to the hypothesis that the patient's functional limitations were associated with the loading of abnormal tissue (stage 2 osteochondral lesion via MRI findings) along the weight-bearing surface of the condyle. Considering the diagnostic imaging and clinical findings, I thought that the patient's lesion was located anteriorly on the weight-bearing surface of the condyle. Her pain was reproduced most intensely during passive knee extension (lesion engaged13) and direct palpation to the area. This was consistent with her unwillingness to fully extend the knee while walking and self-reports of pain mostly with prolonged standing (knee in relative extension) and walking.
I determined that the patient had impaired muscle performance and motor function associated with localized inflammation and connective tissue dysfunction on the articular surface of the right medial femoral condyle. The diagnostic classification was Pattern 4D, "Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Connective Tissue Dysfunction" in the Guide to Physical Therapist Practice.31 Despite the evidence suggesting the lack of an inflammatory process associated with OCD,3 I could not be certain that a localized inflammatory process, such as synovitis, was not active in her knee because of recent tissue overuse.32
A paucity of literature exists to guide clinicians in physical therapist management for an adult with OCD of the knee. Although some authors3,5,8,22 report that conservative management of an adult is not prudent, others4,11 encourage the inclusion of age, characteristics of the lesion (size, location, stability) as determined with diagnostic imaging, and symptoms present when making a decision about nonsurgical care.
Consultation with the orthopedic physician confirmed that the lesion was relatively small (<20 mm) and stable (stage 2) according to MRI findings. The physical therapist examination and MRI findings indicated that my patient had "favorable" conditions8 for conservative management. These conditions included: (1) no swelling or joint effusion, (2) lesion size <20 mm, and (3) no gross dissection (instability) of the lesion. Consultation with the patient revealed her strong desire to pursue nonsurgical management and a willingness to adhere to intervention. Her medical comorbidities were not considered to be complicating factors for physical therapy intervention because of appropriate medical management. The patient's age, diagnostic image findings (stage 2 "stable" lesion), clinical presentation ("favorable conditions" for nonsurgical management), and her specific goals for therapy given her present life circumstances (the need to continue working and avoid surgery due to her upcoming wedding) led me to believe that physical therapy intervention was warranted.
A review of the literature revealed no studies that specifically addressed the use iontophoresis for patients with OCD of the femoral condyles. Many authors,33–37 however, have reported the effects of anti-inflammatory medication delivery via iontophoresis in patients with a variety of inflammatory musculoskeletal conditions, including infrapatellar tendinitis,32 plantar fasciitis,33 rheumatoid arthritis of the knees,34,35,37 epicondylitis, and metatarsalgia.35 In particular, Gudeman et al33 and Hasson et al37 reported that the use of iontophoresis with dexamethasone phosphate (DEX-P) reduced pain and improved early tolerance of a therapeutic exercise program. Therefore, I made the decision to use iontophoresis with DEX-P as a part of the intervention plan based on this evidence. Other interventions were chosen in an effort to minimize stress to the osteochondral lesion.
Intervention
The patient participated in 5 physical therapy sessions at a frequency of 1 to 2 visits per week. Interventions to address the patient's complaints and impairments began on the initial visit. The treatment addressed right knee pain and provided the patient with strategies to decrease loading across the right knee. Iontophoresis was performed using an Iomed Phoresor II unit
with DEX-P (4 mg/mL solution) applied locally over the right anteromedial femoral condyle (Fig. 3). The patient was seated in a supported, long-sitting position, with an 8-in (20.3-cm) bolster placed under both knees. The purpose for the right knee position was to expose the site of the lesion on the anteromedial femoral condyle. Before the application of iontophoresis, moist heat was applied to the anterior knee for 5 minutes to hydrate the skin in an effort to aid drug delivery to the subcutaneous tissues.38 Palpation confirmed the site of tenderness and a small Iogel electrode was placed over this site. This served as the active electrode (anode). A dispersive electrode (cathode) was placed approximately 6 to 8 in (15.2–20.3 cm) distally on the medial calf. The skin was cleaned at both sites with rubbing alcohol prior to the application of electrodes.
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The patient then was instructed in joint protection strategies to decrease loading across the right tibiofemoral joint. First, the patient was encouraged to use cushioned footwear (ie, running shoes) to limit ground reaction forces at the knee. The patient had previously worn clogs at work, which had a firm sole and minimal foot control through the upper shoe. Second, she was instructed to avoid end-range knee extension, including during the gait cycle, because this position most effectively engaged the lesion. In particular, I made a conscious decision to avoid correction of her gait deviations (limited knee extension, stance time and heel-strike on the right) during this early stage of treatment. Third, I discussed the benefit of using an assistive device (ie, straight cane) to provide unloading of the right tibiofemoral joint. The patient, however, was reluctant to use an assistive device and decided instead to initiate the first 2 strategies. We agreed to discuss using an assistive device again if her pain did not improve within the first week of treatment.
A home exercise program was initiated to address the decreased muscle performance of the right lower extremity. The exercises included modified heel slides and modified straight-leg-raising exercises. Modified heel slides (30°–90°) were used to promote pain relief and tissue healing through increased synovial fluid diffusion. Range of motion limits at the knee were used to avoid stress to the lesion site. Modified straight-leg-raising exercises were performed with the knee held in approximately 30 degrees of flexion. Single-plane hip flexion (in a supine position), extension (in a prone position), abduction (in a left side-lying position), and adduction (in a right side-lying position) were performed within full available hip ROM for 2 sets of 10 repetitions each. These exercises were chosen to strengthen the 2-joint muscles that cross the hip and knee joints, to allow for improved load attenuation by these muscles (ie, rectus femoris, hamstring group, gracilis, and tensor fasciae latae/iliotibial band).28 The decision to perform these exercises with the knee fixed in 30 degrees of flexion was an effort to protect the OCD lesion from further loading while initiating strengthening exercises on day 1 of her intervention.
The patient reported a 50% improvement in her symptoms by the second visit, which occurred 5 days after the initial examination. Given the rapid change in her right knee pain at that time, I concluded that the need to consider using an assistive device was no longer warranted. The second and third visits included application of iontophoresis (as described previously), review of the home exercise program, and continued monitoring of right knee symptoms and joint protection strategies.
On the fourth visit, 11 days after her initial visit, the patient reported minimal, intermittent right knee pain (0–1/10) and increased tolerance of all activities. She, however, was still working an 8-hour shift (versus a 12-hour shift before injury) and had not yet resumed her regular walking program. The intervention for this visit remained iontophoresis with DEX-P to the right knee, monitoring of her home exercise program (with an increase to 3 sets of 15 repetitions for all exercises as tolerated), and consultation regarding continued importance of joint protection. Re-examination of gait revealed a more normal gait pattern, with minimal pain noted during either the right lower-extremity stance or heel-strike phases. We discussed a plan to progress her exercise program next visit and began discharge planning.
The patient missed a visit and returned for her fifth and final visit 10 days after the fourth visit. She reported continued improvement in right knee pain (pain rating 0/10) and functional activity tolerance, noting an ability to resume walking her dog for short distances (
–1 mile) without increased knee pain. She reported minor "fatigue" in the right lower extremity at the end of her 8-hour workday. Iontophoresis was discontinued given her 0/10 pain rating maintained over a 10-day period. A full re-examination was performed and a decision for discharge was made in agreement with the patient. Her home exercise program was modified to include strengthening exercises for the muscles about the hip, knee, and ankle that required movement of the tibiofemoral joint. These exercises included modified wall slides (20°–90°) and modified active knee extension (90°–20°) in an effort to promote improved strength and endurance in knee extension through a greater ROM while still avoiding excessive loading to the OCD lesion. Patient education during this last visit included a final review of joint protection strategies at the right tibiofemoral joint and discussion of the importance of integrating regular strengthening exercises into her daily routine as a long-term method to protect the joints of the lower extremity.40,41
| Outcomes |
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TopAbstractIntroductionCase DescriptionOutcomesDiscussionConclusionReferences |
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to 1 mile without difficulty, and reported a 95% rating of function (SANE score). Although the patient's work status continued with a limited 8-hour shift, she reported no pain throughout the work day and was planning to resume her normal 12-hour shift within the 2 weeks following discharge from physical therapy. At the 9-month follow-up (from initial examination), the patient reported "good" right knee function (95% SANE score) with all activities and no pain (0/10). She had been working 12-hour shifts consistently for more than 6 months and was able to walk down the aisle at her own wedding without difficulty wearing high-heeled shoes. Unfortunately, the patient did not complete a follow-up MRI, which had been scheduled 1 year after the initial MRI; therefore, no comparative imaging was available to assess healing of the lesion.
| Discussion |
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Some authors have argued that several factors are responsible for the increased potential of DEX-P diffusion into the underlying tissues with iontophoresis: polarity of the active electrode,42–45 localized cutaneous blood flow,43,46 pH level in the skin,47 and current intensity.43 Although use of the anode as the active electrode was originally posited by Glass et al,48 many authors42–45 have recently provided persuasive arguments for the use of the cathode. At the time I treated this patient, there were discrepancies in the literature and among the clinical pharmacy staff at my facility regarding use of the anode or the cathode as the active electrode with DEX-P. Based on current evidence, however, my facility has been using the cathode consistently as the active electrode when providing iontophoresis of DEX-P for the past 4 years.
Early work by Singh and Roberts,46 using salicylic acid with rats, suggested that increased cutaneous blood flow aided clearance of the solute from the skin. Although little direct evidence that this effect exists in humans, it is credible to suggest that using thermal modalities before or after iontophoresis may diminish the reservoir of medication in the skin available for diffusion to deeper tissues. Anderson et al43 also hypothesized that increased cutaneous blood flow, resulting from high-current iontophoresis (1.5–4.0 mA), may aid clearance of DEX-P, resulting in lower penetration of the drug into subcutaneous tissues.
Recent studies44,45 have shown an absence of DEX-P in the synovium and local venous blood after the application of iontophoresis delivered at a 4.0-mA current. These findings may suggest: (1) a lack of effective DEX-P delivery into the subcutaneous tissues or (2) that the amount of drug delivered was at a level below detection by the methods used in these studies.
Considering the parameters under which my patient received iontophoresis of DEX-P, it is reasonable to suggest that, in light of recent evidence, delivery of DEX-P into the target tissue was minimal and unlikely to account for her pain relief. The application of transcutaneous direct-current electrical stimulation during iontophoresis, however, may have been partially responsible for her early pain relief.
Many authors49–52 have studied the effects of transcutaneous electrical nerve stimulation (TENS) on pain relief in human subjects. Although some authors demonstrated that high-frequency stimulation had the best effect on a subject's perception of experimentally induced pain,50–52 others described how both high- and low-frequency applications of TENS could be effective for pain relief.49,53 In a recent review of nonpharmacological treatments for musculoskeletal pain, Wright and Sluka53 reported evidence that TENS improves joint function in patients with rheumatoid arthritis. These authors, along with Ulett et al,49 also reported on the effectiveness of both high- and low-frequency TENS (ie, electroacupuncture) to inhibit pain through centrally mediated responses in animals and human subjects.
Iontophoresis was delivered to the anteromedial, right knee of my patient through direct-current (low-rate) stimulation for a period of 20 to 25 minutes per treatment session. These parameters, although not identical to other forms of TENS commonly used to achieve analgesia, are similar to low-frequency electroacupuncture (2 Hz, 30 minutes).49 It appears reasonable, therefore, to suggest that her early decreases in pain may have been aided, in part, by the current application from the phoresor unit during treatment application.
It is also possible that the early decrease in symptoms may have been the result of factors other than, or in addition to, the application of electrical stimulation (eg, a change in footwear, addition of the customized home exercise program, the patient's new knowledge of joint protection principles). Her decreased knee pain provided an opportunity for greater tolerance of functional activities (eg, work) and the strengthening exercises prescribed. Muscles have been described as "shock absorbers"54 because muscular contraction has the ability to protect cartilage.40 The ability to effectively engage in a strengthening exercise program, therefore, was necessary. As a result, decreased stress on the chondral lesion might have helped diminish pain and future tissue damage.54
Careful loading (stress) of the lesion must be considered in light of its potential effects on tissue healing. Evidence suggests that the articular cartilage response to stress is dependent on delivering the appropriate amount of tissue loading.32,54 Hefti et al8 and Aichroth11 both found that the "classic" medial femoral condyle lesions demonstrated the least evidence of healing over time. These lesions are located within the intercondylar notch of the femur (non–weight bearing surface) and thus are subject to less loading over time. Patients with a history of increased athletic participation also demonstrated decreased healing rates of OCD lesions.8 Hefti and colleagues8 suggested that this may have been the result of tissue or lesion overload. Therefore, it appears that careful and controlled loading of the articular lesion must be considered given its potential to contribute to healing during conservative management.32,54
The interventions, other than iontophoresis, utilized with this patient were based on clinical decisions that used the formula stress=force/area as their foundation.30 Interventions were chosen primarily in an effort to decrease the amount of force applied to the tibiofemoral joint (ie, change in footwear, avoidance of knee extension during first week of treatment, patient education regarding modification of standing time at work, effects of increased body weight and strengthening exercises for muscles crossing the joint).
The patient reported a change in her footwear and initiation of activity modification immediately after the initial physical therapy intervention. Given the unloading effect that these actions may have had on the tibiofemoral joint, it appears that her early and continued decreases in pain may have been aided, in large part, by a decrease in the overall force placed on the lesion. Although a centrally mediated analgesic effect from the electrical stimulation remains a plausible explanation for her early symptom relief, at the 9-month follow-up she said that she believed the change in footwear had the greatest overall influence on the successful resolution of her knee pain.
Linden55 stated that, within the natural progression of adult OCD, degenerative changes generally occur only after a long asymptomatic period. For example, he described patients with OCD who developed symptoms of degenerative arthritis after nearly 20 years. The focus on joint protection education, therefore, was made to provide for present symptom management and preventive measures against further articular cartilage degeneration. It was my responsibility to provide the patient with information that may help to limit further future injury to her knee.
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| Footnotes |
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This work was presented, in part, at the Annual Conference of the Pennsylvania Physical Therapy Association, October 26–28, 2001, Seven Springs, Pa, and at the Combined Sections Meeting of the American Physical Therapy Association, February 20–23, 2002, Boston, Mass.
* Pfizer Inc, 235 E 42nd St, New York, NY 10017. 
Iomed Inc, 2441 South 3850 West, Ste A, Salt Lake City, UT 84120.
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