Delaying Knee Replacement: Driven to Distraction?
This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.
Some symptomatic patients with knee osteoarthritis (OA) present relatively early in the radiographic disease process, while others present after serious articular cartilage loss has occurred. In either case, young knee OA patients are often looking for ways to get relief while postponing a total knee arthroplasty (TKA).
One such recently introduced alternative is knee joint distraction (KJD), a joint-preserving surgery used for bicompartmental tibiofemoral knee osteoarthritis or unilateral OA with limited malalignment. Significant long-term clinical benefit as well as durable cartilage tissue repair have been reported in an open prospective study with 5 years of follow-up.1 A more recent study of distraction2 presents 2-year follow-up results of a 2-pronged trial that measured patient-reported outcomes, joint-space width (JSW), and systemic changes in biomarkers for collagen type-II synthesis and breakdown.
In one arm, end-stage knee OA patients who were candidates for TKA were randomized to KJD (n=20) or TKA (n=40). In the second arm, earlier-stage patients with medial compartment OA and a varus angle <10° were randomized to KJD (n=23) or high tibial osteotomy (HTO; n=46). In the distraction patients, the knee was distracted 5 mm for 6 weeks using external fixators with built-in springs, placed laterally and medially, and weight-bearing was encouraged. WOMAC scores and VAS pain scores were assessed at baseline and at 3, 6, 12, 18, and 24 months.
At 24 months, researchers found no significant differences between the KJD and HTO groups in that part of the trial. In the KJD/TKA arm, there was no difference in WOMAC scores between the two groups, but VAS scores were lower in the TKA group. The improvement in mean joint space width seen at one year in the KJD group of the KJD/TKA arm decreased by two years, though the values were still improved compared to baseline. However, the joint space width improvement seen at 1 year for both groups in the KJD/HTO arm persisted for two years. For all KJD patients, the ratio of biomarkers of synthesis over breakdown of collagen type-II was significantly decreased at 3 months but reversed to an increase between 9 and 24 months.
It is hard to believe that 6 weeks of joint distraction could trigger a process that yields such positive and long-lasting results. While much more research with longer follow-up is needed, KJD may prove particularly useful in younger knee OA patients trying to delay joint replacement.