Abstract
Early revision after total knee arthroplasty (TKA) is fortunately uncommon. However, instability and lack of fixation are common early failure mechanisms. Cement techniques utilizing lavage and multiple drill hole interdigitation of the resected tibial surface can reduce micromotion and produce reliable tibial component fixation. This study looks at clinical failure mechanisms, cement technique and polyethylene damage in patients needing early revision of cemented TKA.
PCL-retaining TKA with cement fixation was performed on > 1000 patients at a single institution. Cement techniques varied with surgeon, with some using lavage and drill hole preparation of the resected surface and others electing to cement the surface “as cut”. Seventeen patients were revised within three years of follow-up. Revision reasons included loosening (41%), instability (18%), infection (24%), pain (12%), and malposition (6%). Prospective outcome scores, radiographic data, revision reasons, and polyethylene wear were compared.
Pre-revision pain and function scores gradually decreased back to pre-operative levels. Leg alignment averaged 7° varus (nine patients) and 12° valgus (eight patients) pre-operatively and 5° valgus at pre-revision. Tibial radiolucent lines were present medially only in nine knees and medially and laterally in four knees. The majority of patients revised for loosening had a tibial component cemented onto the “as cut” bone without additional preparation. Damage covered 32%-85% of the polyethylene articular surface. Scratching and pitting were significantly correlated (p< 0.05) with shorter in-situ time and revision for instability and loosening. Alignment and outcome scores were not correlated with damage.
In this series of cemented TKA, loosening and instability accounted for 59% of the early failure, similar to the incidence previously reported for cementless TKA. Cement technique and component positioning, not polyethylene wear, were the primary contributing factors. Attention to ligament balancing and achieving better tibial component fixation is needed to further limit the incidence of early failure after cemented TKA.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
