Diagnosis of Chondromalacia Should Not Depend on Presentation of Knee PainKnee pain over the front of the knee, anterior knee pain is quite common, particularly in teens and young adults. What causes this knee pain can be controversial. Many physicians believed that it is caused by chondromalacia patellae, also known as runner's knee, but other causes have also been proposed.
Typically, the person complains of a deep-seated ache and pain just behind the patella (kneecap), most often when climbing stairs, sitting with bent knees, or getting up from a sitting position. Although the pain seems to be more common with bending the knee, it may also be painful to extend the knee if there is resistance. It may also feel unstable, as if the knee won't support the leg. Because this type of pain could be the cause of other problems that need treatment, such as a tear, which could require surgery.
In coming to a diagnosis of chondromalacia patellae, x-rays are only useful in the later stages. Earlier diagnosis could be made with arthroscopy, exploration of the joint using long, slender instruments inserted through tiny incisions, but ultimately, fewer than 10 percent of patients with chondromalacia patellae end up needing surgery, so arthroscopy is an invasive procedure that may not be necessary. The authors of this article looked into the connection between the symptoms of anterior knee pain syndrome and chondromalacia patellae, as well as different tests used for diagnosis.
Researchers recruited 56 patients, aged between 18 and 25 years, 21 of whom had one knee examined and the other 35 had both knees examined. The patients were all in the Finnish military and who were physically active as a result. Assessments included medical examination of the knee, and measurements of motion, muscle strength, limb length, and muscle girth. Tests were also done to assess walking gait, stationary running, hopping and squatting. The McMurray and Apley tests were performed to detect any mechanical problems with the knee, and x-rays from all angles were done.
The first treatment for all patients was nonoperative: rest or limited activity and nonsteroidal anti-inflammatory-drugs (NSAIDs) when needed. If the physician was considering performing arthroscopy, the patients were first encouraged to perform physiotherapist-supervised exercises to strengthen the muscles. If there was no response to nonsurgical treatment and physiotherapy, then an arthroscopy was performed after most patients underwent a magnetic resonance imaging scan (MRI).
Upon reviewing the findings from the examinations, tests, and arthroscopies, the researchers found that arthroscopies confirmed the suspected diagnosis of chondromalacia patellae in 25 of the 56 knees. Eight of the 25 with chondromalacia patellae were rated at a level of grade I (some softening of cartilage), nine were grade II (more softening), eight were grade III (thinning of the surface of the cartilage), and none were grade IV (rough cartilage is smoothed down). Twenty-five knees had synovial plica, a fold of tissue causing irritation in the knee, four had tears, four had lesions, and six knees were normal. One of the issues the researchers were looking for, an association between the severity of chondromalacia patellae, seen by arthroscopy, and anterior knee pain, was not found.
Before the arthroscopy, the researchers noted that:
- 12 knees did not have pain, while 36 did
- 36 of 43 plain x-rays taken showed normal findings in the knee
- Six knees had subluxation (partial displacement) or lateralization (sideways movement) of the kneecap
- One knee showed signs of Osgood-Schlatter disease, which causes knee pain
- One knee had irregular surface of the kneecap
Despite these findings, the arthroscopies found that 14 of the knees that appear normal did have chondromalacia patellae.
The authors concluded that chondromalacia patellae cannot be diagnosed based on symptoms alone or with current physical examination. The researchers found no connection between the severity of or lack of symptoms and the severity of the diagnosed condition. MRI scans did prove accurate for moderate to severe cases, but was not effective for milder cases.
Harri K. Pihlajamaki, MD, et al. Reliability of Clinical Findings and Magnetic Resonance Imaging for the Diagnosis of Chondromalacia Patellae. In The Journal of Bone & Joint Surgery. Feb. 2010. Vol. 92. No. 4. Pp. 927-934.
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