Knee Arthritis in Active Individuals: Matching Treatment to the Diagnosis
Paul A. Dowdy, MD; Brian J. Cole, MD; Christopher D. Harner, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 6 - JUNE 98
In Brief: Even among the active middle-aged population, knee arthritis is a common condition that can greatly decrease quality of life. The 45° flexion weight-bearing radiograph, a crucial diagnostic step, can show joint space loss. Each patient must be treated individually, but conservative treatment with medication, activity modification, exercise, physical therapy, braces, and joint injections may be effective for long periods. Operative modalities include joint arthroscopy and reconstructive procedures such as osteotomy and joint arthroplasty. In injured knees, meniscus and cartilage transplants may prevent the development or progression of osteoarthritis. Total knee arthroplasty should be considered in active patients only when all other options have been exhausted.
Knee arthritis is a common musculoskeletal affliction, and its most prevalent form is primary osteoarthritis (OA) (1-3). Women are affected more often than men, and an estimated 25% to 30% of people between 45 and 64 and 60% of people older than 65 have radiographically detectable OA (4).
Limitations common to many knee OA patients include difficulty using stairs and squatting. High-impact activities such as exercises or activities that include running or jumping can be detrimental and painful. These difficulties can significantly reduce quality of life for an active individual.
Because of its common occurrence and its effect on quality of life, a proper approach to management of OA of the knee is imperative, especially for patients who wish to become or remain active.
History. Patients who have knee arthritis commonly have pain and/or functional disability. Pain can be localized to one compartment of the knee (ie, medial, lateral, or patellofemoral), or it can be diffuse. It is usually activity related and is worse by the end of the day. Patients generally have difficulty ascending and descending stairs and squatting, and their pain may be associated with intermittent or constant swelling. A patient's knee may lock, suggesting either a meniscus tear or a loose body, or there may be subjective instability. It should be determined whether the knee is giving way because of pain or because of actual mechanical instability.
Knowledge of medications and modalities that the patient has used to reduce pain should be sought, and the patient's occupation and current and desired activity level should be determined.
Physical examination. The patient's body habitus should be observed. Overall alignment of the leg gives a clue to which compartment is involved. Genu varum suggests medial compartment involvement, while genu valgum suggests lateral gonarthrosis.
The patient's range of motion should be determined. A physically active OA patient commonly has a maximum flexion of less than 130°, as compared with a normal maximum flexion of 140° to 150°. Greater loss of motion is unusual in an active patient but does not suggest a specific condition. Patients commonly have an element of patellofemoral crepitus.
Patellar tilt should be determined clinically. Lateral and medial patellar glide is measured with the knee in full extension by assessing how far the patella translates medially and laterally. Patellar facet tenderness is determined by palpation.
Knee stability in the coronal (ie, varus/valgus) and sagittal (anteroposterior [AP]) planes should be determined. Patients who have medial gonarthrosis and a varus deformity commonly have medial pseudolaxity (a sensation of valgus laxity as the varus deformity is manually corrected with the patient supine and leg extended).
The patient may have increased tibial translation on Lachman's and anterior drawer testing and a positive pivot shift maneuver, indicating chronic anterior cruciate ligament (ACL) insufficiency, which can lead to OA (5).
The neurovascular status of the limbs should be carefully examined because of the relatively high prevalence of atherosclerosis in the older population. The hip and back should also be examined thoroughly to rule out any contribution to the patient's symptoms.
Radiographs. The radiographs we obtain routinely are weight-bearing posteroanterior views of both knees in 45° of flexion (figures 1 and 2) (6); a true lateral view of the affected knee; and an axial (Merchant(7)) view of both patellae (figure 3). Radiographs should be examined for joint-space loss, subchondral sclerosis, osteophyte formation (8), loose body formation, chondrocalcinosis, deformity, lateral patellar tilt, and subluxation.
The 45° flexion weight-bearing radiograph is crucial because it may show a loss of joint space that traditional extension views do not, indicating early chondrosis (figure 2). If deformity is clinically apparent, standing AP radiographs from the hips to the ankles should be obtained to determine alignment.
Magnetic resonance imaging. Unless there is a question about degenerative meniscal pathology, we do not routinely order magnetic resonance imaging (MRI) for patients who have knee arthritis. Joint-space narrowing on full-weight-bearing films is sufficient to make a diagnosis of chondrosis, rendering MRI unnecessary. If there is a suggestion of osteonecrosis, MRI is excellent for determining the location and extent of the lesion.
Bone scintigraphy. Bone scans are excellent for determining the activity and extent of a disease process (9). We find them most helpful when a patient has arthritis-like symptoms but plain radiographs are normal, because the bone scans can still be positive. Bone scan results allow for counseling the patient on the diagnosis and directing treatment. For example, in a patient who has patellofemoral syndrome, a positive bone scan in the lateral facet of the patella indicates increased pressure on the patella, which will need to be addressed in initial rehabilitation.
Since knee OA is a chronic condition that commonly takes many years to progress significantly, the physician has ample time to try different treatments. Most patients can be treated nonoperatively for a significant length of time. We generally treat knee OA with easy-to-follow steps similar to those recommended by the American College of Rheumatology (10).
Medication. The first line of treatment is nonsteroidal anti-inflammatory drug (NSAID) therapy. Currently, there are at least 15 NSAIDs on the market(11,12) (table 1: not shown). There have been no definitive studies that clearly show superior efficacy for any one NSAID (13).
All NSAIDs have been associated with significant risks and side effects. They work by inhibiting the cyclooxygenase pathway of arachidonic acid metabolism, blocking the production of proinflammatory prostaglandins but also blocking the beneficial effects of prostaglandins on gastric mucosal lining, renal blood flow, platelet function, and sodium balance.
The most common side effects, therefore, are the production of peptic ulcer disease, ulceration, and perforation; renal toxicity and/or failure; and cardiac failure. Most of these effects are dose related, and all are especially severe in the elderly. Some NSAIDs tend to have a lower side-effect profile than others (11) but still must be used with caution and a high index of suspicion for complications.
We recommend that patients use the lowest effective dosage, take the drug with food, and use it for the shortest time possible. We generally start by using an inexpensive, relatively fast-acting NSAID such as ibuprofen. We try this medication for at least 4 weeks before prescribing a different NSAID if necessary, switching sooner if a side effect develops.
If compliance with ibuprofen is a problem because of frequency of administration (three times a day), we prescribe a once-daily medication. If there is a contraindication to using an NSAID, we use acetaminophen.
Another therapy being used by some patients is the dietary supplement glucosamine sulfate. Anecdotal patient reports indicate that some have had positive results, but others have not been helped. We are waiting for adequate scientific evidence before considering whether to recommend it.
Along with medication, we routinely use other nonoperative modalities, such as activity modification, physical therapy, and bracing.
Activity modification and exercise. Activity modification to minimize symptoms should be based on the patient's present occupation and activity level. High-impact activities that include running and jumping are the most detrimental for someone who has knee arthritis (4). Low-impact activities such as swimming and bicycling are the most beneficial for the arthritic knee. If the patient has significant patellofemoral chondrosis, activities that load the patellofemoral joint, such as squatting or ascending and descending stairs, should be avoided.
With activity modification, maintaining a healthy body weight is usually a very difficult issue since it is hard for patients to maintain or increase their calorie expenditure (activity level) with a painful knee. If possible, patients should maintain a regular exercise program to maximize aerobic conditioning and calorie expenditure.
Physical therapy. Physical therapy is an important treatment modality for the active individual who has knee arthritis. The goals of therapy are to increase range of motion, flexibility (especially in the hamstrings), and quadriceps and hamstring strength. Tight hamstrings are very common in patients who have OA, and they exacerbate the knee pain.
Hamstring stretching can be done supine, sitting, or standing (figure 4). Quadriceps rehabilitation starts with quad sets (figure 5) and isometric strengthening (eg, straight-leg raises, figure 6). The patient then moves on to rehabilitating the knee with closed-kinetic-chain strengthening of the quadriceps and hamstrings, in which the foot is kept planted on the ground (figure 7). This leads to cocontraction of the hamstrings and quadriceps muscles with resulting decreases in patellofemoral joint forces, ACL strain, and tibial translation.
Using a knee sleeve during physical therapy can help active patients regain a sense of stability, possibly by enhancing their awareness of the knee joint (proprioception). Another key element that physical therapy provides is the opportunity for patients to work through their pain safely, under supervision, since they should normally stop exercising when pain results.
Bracing. Varus unloading braces such as the GII Unloader (Generation II Orthotics, Richmond, British Columbia) can be used in patients who have medial compartment arthrosis, varus alignment, and pain localized along the medial joint line. Some patients find the braces cumbersome and will not use them. For patients who can tolerate wearing the brace, especially those who are not candidates for surgery, we have found the varus unloading brace useful. We have noted, however, that although these braces are helpful in the short term, patients often elect not to use them on a day-to-day basis.
Knee injection and aspiration. We find intra-articular corticosteroid injection helpful for patients who have not been helped by NSAIDs and for those for whom NSAIDs are contraindicated. We do not usually aspirate the knee unless there is a tense effusion present.
The solution (1% lidocaine [3 mL] and triamcinolone diacetate [40 mg], or betamethasone sodium phosphate [6 mg]) is injected into the anterolateral soft spot under sterile conditions (figure 8). If the patient has a tense effusion, we aspirate this first with an 18-gauge needle in the suprapatellar pouch (figure 9).
We find the duration of the effects of this injection to be extremely variable, lasting anywhere from a few days to more than 6 months. The injections are less effective with each successive injection. We limit corticosteroid injections to three or four treatments a year, spaced 3 or 4 months apart.
If the judicious use of injected corticosteroids has failed, we have begun to offer a trial of sodium hyaluronate injections to those patients who have mild arthritic changes and/or are not operative candidates.
Standard Surgical Treatment
Arthroscopy. In OA of the knee, proinflammatory cytokines are released into the knee from the degenerating articular cartilage and from the synovium. The role of arthroscopy and debridement, at least in part, appears to involve "washing out" or diluting these inflammatory mediators. This effect is temporary, and arthroscopy can be thought of in most cases as buying time (14).
Patients who benefit most from arthroscopy and debridement are those who have a history of knee locking because of a meniscus tear, loose body, or loose chondral flap, and those who have recent onset of symptoms (less than 6 months), normal alignment, and mild-to-moderate radiographic evidence of OA (15-17). Arthroscopy has a significant placebo effect (18), and there are some who feel that in the absence of mechanical symptoms, office needle lavage is just as efficacious as arthroscopy and debridement (19-21).
In the absence of mechanical symptoms, we are extremely careful in recommending arthroscopy. If the patient has undergone a minimum of 3 months of supervised nonoperative treatment and has normal alignment and only mild-to-moderate OA on 45° flexion weight-bearing radiographs, then we will offer arthroscopy and debridement. We tell the patient that in this situation there is about a 50% to 60% chance of improving their symptoms (15-17).
For young, active patients who have knee arthritis and normal alignment, often the only solution is to buy them time with arthroscopy, since they are too young for joint replacement. Also, arthroscopy can be performed concurrently with an osteotomy if the patient has knee locking.
Osteotomy. The ideal candidate for osteotomy is young (under 65) and active and has isolated medial or lateral compartment OA, joint pain localized to the affected compartment, good neurovascular status, and an associated angular deformity of less than 15° (22,23).
A high tibial osteotomy with a lateral closing wedge (figure 10) is the most common and is performed when medial compartment OA is associated with a varus deformity. Another osteotomy performed for a varus deformity is a high tibial osteotomy with a medial opening wedge. In this procedure, a wedge of bone fashioned from the iliac crest is placed into a transverse osteotomy from the medial aspect of the proximal tibia (figure 11). This procedure is performed in the patient who has medial compartment OA associated with a varus thrust during gait. With a varus thrust, the knee goes into significant varus alignment during the stance phase of walking but "thrusts" out of varus during the swing phase. Such a patient has medial laxity, and a lateral closing wedge osteotomy would exacerbate the laxity and varus thrust.
For lateral compartment OA associated with a valgus deformity, the high tibial osteotomy with a medial closing wedge or a distal femoral varus osteotomy can be performed. The former is chosen for mild degrees of valgus alignment (less than 12°), while the latter is chosen for valgus greater than 12° and with a lateral sloping joint line (24).
We have found that when used in appropriately selected patients—especially the young—osteotomy is very effective. About 80% of our patients do well for 5 years, and 50% to 60% have significant relief for 10 years. These results are consistent with the literature (22,23).
Joint arthroplasty. Total joint arthroplasty has a minimal role in treatment for the active patient. In relatively young, active individuals, replaced joints are subjected to high levels of repetitive stress that predispose implants to wear, loosening, and osteolysis (25). Total knee replacements work best in sedentary patients older than 65.
We consider the procedure if conservative therapy in an active individual has failed despite good compliance, if there is no indication for another procedure such as arthroscopy or osteotomy, if the patient is over 50 years old, and if he or she is willing to give up all high-impact activities. In such patients we have found total knee replacement to be very satisfactory, with 90% to 95% good to excellent results for 10 years.
Meniscus and Cartilage Transplants
If a patient has lost either the meniscus or articular cartilage, an implant of a new meniscus or cartilage that would prevent the onset and/or progression of OA would be ideal. This is the goal of meniscus transplantation, autologous articular cartilage transplantation (cells or local bone/cartilage plugs), and osteochondral or osteoarticular allograft transplantation.
Meniscus transplantation. We began meniscus transplantation in 1992 and have performed 45 procedures to date. This procedure is indicated in a patient who has had a previous meniscectomy, persistent pain, intact articular cartilage, normal alignment, and a stable joint. If the joint is unstable because of ACL or posterior cruciate ligament injury, these ligaments are reconstructed at the time of transplantation.
We recently reviewed our first 25 meniscal transplant patients who had had surgery at least 1 year earlier. About half also had ACL reconstruction. Pain relief was excellent. The overall knee rating, according to the University of Pittsburgh Knee Scale, was 87/100 (range 75 to 100). Patients rated overall function as normal or nearly normal in 21 cases and abnormal in 1 case (3 patients could not be located). Fully 21 of 22 patients were markedly improved. From this initial follow-up we feel that meniscus transplantation has a role in caring for these difficult-to-treat patients (26-28).
Articular cartilage transplants. Articular cartilage transplantation is indicated for persistent pain and a focal area of articular cartilage loss due to trauma or osteochondritis dissecans in an otherwise preserved joint. These patients usually have a defect on the femoral condyle.
There are three main techniques for transferring articular cartilage: autologous articular cartilage transplantation, local transfer of articular cartilage with a plug of bone from another area of the knee (mosaic chondroplasty), and transplantation of allograft articular cartilage with a segment of bone. We have performed five autologous articular cartilage transplants and a few mosaic chondroplasties and are satisfied with our preliminary results.
Other techniques. Osteochondral allograft reconstruction and osteoarticular allograft reconstruction are transplant procedures in which the articular cartilage with a segment of subchondral bone or a whole segment of an articular surface and its underlying bone (eg, a whole condyle) are transplanted into the knee joint. These treatments are indicated when both articular cartilage loss and underlying bone loss have occurred (29-31). These are complex, rare procedures that should be performed by experienced surgeons in centers where allograft bone is in ample supply.
Treatment of knee OA must be individualized, but special treatment considerations apply to younger, active patients. Surgery may be indicated, but these patients are often poor candidates for total knee arthroplasty. We have found that, for most active knee OA patients, conservative treatment can be successful for prolonged periods, and that patients often benefit from low-impact exercises such as swimming and bicycling.
Dr Dowdy is an attending orthopedic surgeon at the Central Florida Sports Medicine Institute and Central Florida Bone and Joint Institute in Davenport, Florida. Dr Cole is an assistant professor in the department of orthopedic surgery at Rush-Presbyterian-St Luke's Medical Center in Chicago. Dr Harner is an associate professor in the department of orthopedic surgery and chief of the division of sports medicine at the University of Pittsburgh Center for Sports Medicine and Rehabilitation in Pittsburgh. Address correspondence to Christopher D. Harner, MD, Division of Sports Medicine, University of Pittsburgh Center for Sports Medicine and Rehabilitation, 4601 Baum Blvd, Pittsburgh, PA 15213.
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