MKSAP: 34-year-old man with progressive left knee pain

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 34-year-old man is evaluated for progressive left knee pain. The pain causes difficulty with his work as a mail carrier, particularly when walking. His occupation does not require repetitive bending. He played football in college and experienced left knee trauma during sports participation; he underwent left meniscectomy and stopped playing sports. His mother has osteoarthritis of the hands that developed at age 65 years.

On physical examination, vital signs are normal. BMI is 27. Bone hypertrophy of the left knee is noted. There is crepitus but no warmth, erythema, swelling, or effusion of the knees.

Plain radiographs (anteroposterior views) show medial joint-space narrowing of both knees but greater on the left as well as osteophytes and bony sclerosis of the tibial plateau of the left knee; there is no periarticular osteopenia or erosive or destructive changes.

Which of the following is the most likely cause of this patient’s left knee osteoarthritis?

A: BMI
B: Family history
C: Meniscectomy
D: Occupation

MKSAP Answer and Critique

The correct answer is C: Meniscectomy.

The most likely cause of this patient’s left knee osteoarthritis is meniscectomy. The history of prior injury followed by meniscectomy puts this patient at substantial risk for the development of osteoarthritis at an earlier age than would otherwise be predicted. A recent prospective study with a 40-year follow-up concluded that meniscectomy leads to osteoarthritis of the knee with a resultant 132-fold increase in the rate of total knee replacement in comparison to their matched controls. The risk of osteoarthritis of the knee following meniscus injury and removal is also well documented for adolescent athletes and, as recognition of this link has become more widespread, the incidence of meniscus repair rather than meniscectomy has risen.

Other factors for osteoarthritis are advancing age, obesity, female gender, and genetic factors. For example, obesity is the most important modifiable risk factor for osteoarthritis of the knee, but this patient is not obese. The incidence of knee osteoarthritis is also increased by occupations with repetitive bending, which this patient does not experience. The prevalence of osteoarthritis of the hip and knee is nearly two times higher in women than in men. Osteoarthritis of the hand has strong female and genetic predilections; it is also associated with obesity. His mother’s hand osteoarthritis is probably not relevant for this patient who developed knee osteoarthritis at an early age following meniscectomy.

Key Point

  • There is an increased risk of early-onset knee osteoarthritis in patients with a history of prior injury followed by meniscectomy.

This content is excerpted from MKSAP 17 with permission from the American College of Physicians (ACP). Use is restricted in the same manner as that defined in the MKSAP 16 Digital license agreement. This material should never be used as a substitute for clinical judgment and does not represent an official position of ACP. All content is licensed to KevinMD.com on an “AS IS” basis without any warranty of any nature. The publisher, ACP, shall not be liable for any damage or loss of any kind arising out of or resulting from use of content, regardless of whether such liability is based in tort, contract or otherwise.

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