The increasing recognition of unicompartmental knee arthritis as a treatable disease has led many surgeons in recent years to explore the expanding indications for UKA. Traditional indications proposed by Stuart C. Kozin, MD, and Richard Scott, MD, were rigorous, leaving many potential candidates no other option than total knee arthroplasty, particularly the young, active population. While TKA does return patients to sports, it is often to lower impact activities, which may lead to poor patient satisfaction in the ever-growing young, high-demand patient with single compartment disease.

Literature on return to sporting activities after UKA is limited, mainly of smaller cohorts, making clinical recommendations challenging for the surgeon to guide appropriate patient expectations postoperatively. With the expanding indications and higher demand, younger population, it is important to explore the impact of sporting activities on survivorship after UKA.

Crawford and colleauges assessed the impact of postoperative activities on implant survivorship, function, complications and reoperations after UKA in a large cohort of the two senior surgeons. Patients were divided into either a low activity group or high activity group. At an average postoperative follow-up of 9 years, survivorship was 94% with an 8.4% revision rate in the low activity group and 6.2% revision rate in the high activity group. The most common cause for revision was arthritic progression that accounted for 38.5% and 42.9% of the revision in the low activity and high activity groups, respectively. Average time to failure was 17.7 months longer in the high activity group. The high activity group had greater improvements in Knee Society clinical, functional and pain scores postoperatively.

The concerns of returning to more vigorous and higher impact activities after UKA are accelerated polyethylene wear or aseptic loosening of the prosthesis. Only 2% of the low activity group (23.1% of the revisions) underwent revision for aseptic loosening; however, there were no cases of aseptic loosening in the high activity group, mitigating this concern when allowing patients to return to more rigorous activities. It is important, however, to closely monitor these patients to intervene with perhaps a less invasive procedure if necessary. As the authors pointed out in the low impact group, one patient simply underwent a poly change that is more desirable than having to replace all components. In our practice, we routinely see all patients who have undergone joint arthroplasty every 1 to 2 years to evaluate for early signs of failure. To date, however, we have not seen early signs of loosening or poly wear, regardless of sporting activity including those patients who have returned to running, skiing, golf and tennis (UCLA 8, 9, 10) following medial or lateral UKA with similar results as these authors describe.

Another common clinical scenario in the young, osteoarthritic knee is ACL deficiency, which poses another challenge in the management of these patients. Patient history and symptoms are important to determine the presence/absence of anterior knee instability to aid in clinical decision making. If there are no signs of functional anterior instability, then proceeding with UKA without ACL reconstruction may also be permissible in the correctly selected patient. Intraoperatively, consideration must be given to the posterior tibial slope. It is recommended that posterior tibial slope should be less than 7° to reduce anterior tibial translation. If, however, patients also complain of anterior knee instability, ACL reconstruction may be warranted either simultaneously at the time of UKA or as a staged procedure.

While single compartment arthritis in the young, arthritic knee may pose a challenge to some, UKA in the appropriately selected patients is a viable option to eliminate pain, restore function and return active patients to their desired sporting activities. As health care practitioners, it is important to longitudinally evaluate clinical outcomes and patient reported outcome measures to help guide surgeons as well as to set realistic patient expectations to yield high patient satisfaction. We commend these authors for leading the way.

Reference:

Witjes S, et al. Sports Med. 2016;doi:10.1007/s40279-015-0421-9.