The patient’s legs had been bowed for 35 years, but the pain was a new development.
Figure 1. Each knee revealed 25-30 degress of varus angulation
A 77-year-old Asian man presented to the community free clinic complaining of bilateral knee pain. Mr. C, one of 46 million uninsured patients in the United States, had no significant past medical problems, but also no history of prior medical care. His knee pain had developed insidiously over the past five years, progressively worsening to the point that he was unable to ambulate without a cane.
Since Mr. C spoke no English, his granddaughter translated. He admitted to significant pain with activity, especially walking up and down stairs. He had tried Chinese herbal medications, both topical and oral, to no avail. Our focus was on deciphering the patient’s translated history. It was only after seeing him stand that our concerns were heightened.
Mr. C exhibited an extreme, bilateral genu varum (bowlegs) deformity (Figure 1), bringing to mind photos of childhood rickets we had seen in orthopedics texts. Each knee revealed an estimated 25º-30º of varus angulation. Valgus (medially directed) stress resulted in significantly increased pain bilaterally.
Marked crepitus was heard in the patellofemoral joints. Passive range of motion was limited bilaterally to between 5º and 110º of flexion. There were negative findings bilaterally on anterior/posterior drawer, Lachman’s, pivot-shift, Apley’s compression, and McMurray testing. Both knees revealed positive patellar grind with negative patellar ballottement testing. Although his knees exhibited bony hypertrophy, there was no obvious soft-tissue swelling, erythema, or heat to suggest septic joints. Ambulation was slow, with small steps and a moderate waddling gait due to the lower-leg deformity.
While severe osteoarthritis (OA) was clearly part of our differential diagnosis, we also were concerned about a number of other problems, including metabolic bone disease, such as osteomalacia (often called rickets in children), untreated Blount’s disease (infantile/juvenile pathologic bowlegs), hereditary hypophosphatemic (X-linked vitamin D-resistant) rickets, and tumor-induced osteomalacia. Many of these diseases are admittedly “zebras,” but lack of previous medical care raised significant concerns about an undiagnosed condition.
In order to visualize the medial and lateral compartments and assess for joint-space narrowing, we ordered weight-bearing anteroposterior as well as bilateral sunrise views to inspect the patellofemoral compartments for cartilage loss, osteophytes, and irregular bony surfaces. A comprehensive metabolic profile (CMP), phosphorus determination, and complete blood count (CBC) were done. Testing choices considered his lack of insurance and the clinic’s limited resources.
Of significant help was the additional history Mr. C provided at his follow-up visit. He reported, via translator, that his lower-leg bowing began about 35 years ago when he was in his 40s. He had only begun to feel knee pain over the past five years. He reported no prior fractures, and his family history was unremarkable for osteoporosis, increased kyphosis, OA, rheumatoid arthritis, or others with bowed-leg deformities.
Mr. C arrived in the United States in 2005 from Fuzhou, China, an area with a hot and sunny climate. There, he was in the sun daily, working as a rice farmer from a very young age.
A few other individuals in his village developed similar leg bowing at about the same age. His diet did not include vitamin D-fortified cow’s milk. He reported no tobacco, alcohol, or drug use and had been on no medication except the previously mentioned herbal remedies.
Figure 2. Side-by-side x-rays showed bilateral varus angulation
The patient’s CMP and CBC were essentially unremarkable, with normal values specifically noted for his calcium, phosphorus, and alkaline phosphatase. When measured, his 25-hydroxyvitamin D (25[OH]D), the active form of vitamin D used to assess for deficiency, was low-normal at 30 ng/mL. Many endocrinologists now consider 25(OH)D to be normal at >40, insufficient at <20, and deficient at <10.1 Since more than 90% of vitamin D production is derived from sunlight exposure, this weathered former farmer was at low risk for long-standing hypovitaminosis D, despite his dark complexion. His current vitamin D level was likely a function of his recent residence in central Pennsylvania, where sunlight is not always plentiful.
Mr. C’s knee x-rays revealed advanced arthritic changes with bilateral varus deformity and significant osteophyte formation (Figure 2). Both knee films showed marked joint-space narrowing and subchondral sclerosis at the medial-joint compartments. Subsequent bilateral long-standing films on trifold cassette were obtained to assess for concomitant leg-length discrepancy. The patient’s right leg was 19 mm shorter than his left, a direct result of his deformity.
A normal calcium, phosphorus, and CMP ruled out rickets and other metabolic bone diseases. Furthermore, normal lab values and an otherwise normal exam reduced the likelihood of an occult neoplastic process contributing to osteomalacia.
The classic radiographic findings of osteophyte (spur) formation at the joint margins, asymmetric joint-space narrowing, and subchondral sclerosis all pointed to a diagnosis of OA, the most common form of arthritis. Not surprisingly, this is also the second-most common cause of long-term disability among adults in the United States. More than half of individuals older than 65 have radiographic evidence of OA, and essentially everyone will demonstrate these changes after age 75.
Besides age, occupations that predispose to repetitive joint trauma are a risk factor for OA. Years of squatting in rice paddies contributed greatly to our patient’s deformity.
Mr. C was somewhat resistant to using Western medications. Acetaminophen and free samples of celecoxib (Celebrex) were left unused in favor of the “herbal” supplement we also suggested, glucosamine chondroitin sulfate, which he did take.
At his one-month follow-up appointment, a corticosteroid injection (1.5 cc methylprednisolone [Depo-Medrol]/0.75 cc lidocaine 1%/ 0.75 cc bupivacaine [Sensorcaine]) provided immediate pain relief. This was repeated two months later, again producing significant pain relief. Orthotics were recommended for the leg-length discrepancy but deferred due to cost. The patient did agree to OTC shoe inserts, however, and continued to take the glucosamine chondroitin sulfate. In school, clinicians are admonished to “think horses, not zebras, when hearing hoofbeats.” The corollary is to remember horses, even when we see what looks very much like a zebra at first glance. Horses have much to teach as well.
Dr. Flanagan is an associate professor of family and community medicine, Penn State College of Medicine, Hershey, Pa., who teaches in State College, Pa. Mr. Economedes is a fourth-year medical student at Philadelphia College of Osteopathic Medicine.
1. Jan de Beur SM. Vitamin D deficiency. Presented at: Current Clinical Issues in Primary Care at Pri-Med; October 8, 2005; Baltimore, Md.