Patellar tendon laxity in systemic lupus erythematosus

Tendon rupture in patients with systemic lupus erythematosus (SLE) is a rare complication that appears to result from high doses of steroids over long periods.¹ There are reports of patellar ruptures in patients with SLE. Reported here is the first case in the literature of patellar tendon laxity in a patient known to have SLE, which was treated surgically before it could rupture. Also described is the surgical technique used to treat this rare complication.

Case report

The patient is a 49-year-old man diagnosed with SLE 14 years ago, for which he received prednisone (20 mg every other day) for 10 years. He was otherwise healthy. He was referred to the second author's clinic because his left knee “gave way”; a lack of full extension had also been apparent for a few weeks. He denied having any history of left-knee trauma or past problems.

Physical examination revealed an attenuated patellar tendon and 30° lack of active extension. No defects were palpable in the patellar or quadriceps tendons. He complained of the knee giving way while walking. X-rays showed patella alta (Fig. 1). Our preoperative diagnosis was chronic patellar tendon disruption; we planned a surgical exploration and repair.

FIG. 2. Lateral view of the left knee after corrective surgery.

At surgery, a midline longitudinal incision from the patella down to the tibial tubercle exposed the site. When we opened the peritenon we found the patellar tendon completely intact but having about 5 cm of laxity. A 10–11-cm frontal sagittal cut from the tubercle down to the anterior shaft of the tibia was made with an oscillating saw. The distal 5 cm of this bony block was removed. Then we slid the patellar tendon with its bony insertion 5 cm distally, and fixed it there temporarily with k-wires. The knee was then flexed to 90° to align the patella and to approximate an appropriate tension of the patellar tendon. The bony block was then fixed with 2 cortical screws, countersunk. The patellar tendon itself was fixed proximally with 3 cancellous screws with washers (Fig. 2).

FIG. 1. Lateral radiograph of the patient's left knee, revealing patella alta.

Intraoperatively, the patient had full passive extension and flexion. Postoperatively, his leg was placed into a hinged brace locked at full extension; the flexion was gradually increased by 10° each week. Eventually he was weaned from the brace with rehabilitative physiotherapy. Over the next 2 years he was seen several times. Physical examination confirmed a full range of motion in his left knee, with full active extension. He has no instability of the knee when he walks, and his activities are not limited.

Discussion

Tendon rupture in SLE is a known complication,^1,2,3,4 but its etiology remains unclear. Corticosteroid therapy and collagen disease, either singly or together, seem to provide suitable conditions for rupture.³ As yet it is impossible to predict which patients with SLE will develop this problem,³ and still unknown whether a recent exacerbation of SLE disposes tendons to rupture.⁵ Patellar tendon rupture is increasingly recognized, with many spontaneous ruptures in patients with SLE reported.^1,2,3,4,5 Bilateral patellar⁵ and simultaneous patellar and quadriceps tendon ruptures⁵ have been described.

To our knowledge, this is the first case in the literature of a patient with SLE who developed laxity of the patellar tendon and was managed surgically before it went on to rupture. The new surgical technique we described was very successful, and the patient returned to his regular, unrestricted activities.

Competing interests: None declared.

Correspondence to: Dr. Abdulaziz Al-Ahaideb, 733 Revell Cres., Edmonton AB T6R 2E9; ahaideb@hotmail.com

Accepted for publication Feb. 20, 2004