The length of the patellar tendon after unicompartmental and total knee replacement

Abstract

Patella infera may occur after reconstruction of the anterior cruciate ligament (ACL), high tibial osteotomy and total knee replacement (TKR). Restriction of movement of the knee and pain may result. Our aim was to compare the incidence and to assess the effects of patella infera after TKR and unicompartmental knee replacement (UKR). We reviewed radiographs of the knees of 84 patients who had had either TKR or UKR as part of a randomised, controlled trial The length of the patellar tendon was measured on serial radiographs taken before, at eight months and at five years after operation. There was no significant change in the length of the patellar tendon after UKR, but a significant reduction was observed after TKR. Five years after the operation, the shortening of the tendon had increased to a mean of 3.5 mm. Of the knees with TKR reviewed at five years, 34% developed patella infera, defined as 10% or more of shortening, compared with 5% of those with UKR. Shortening was greatest in those knees which had required a lateral release; in this subgroup the mean shortening was 7.2 mm. Shortening correlated with restriction of movement and pain in the knee. Our study has shown that patella infera develops in most patients after TKR with lateral release, and in approximately 25% of patients after TKR without this additional procedure. Patella infera rarely occurs after UKR. It is associated with restriction of movement and pain in the knee. It may be an effect of the more extensive exposure required to perform TKR and may, in part, explain the better clinical results of UKR.

Evaluation of patellar height and measurement methods after valgus high tibial osteotomy

“…In our series, all of the patients had internal fixation and early motion postoperatively. Weale et al [24] investigated the length of the patellar tendon after primary unicompartmental knee arthroplasty (UKA) and TKA. They found a significant reduction after TKA and no significant change after UKA.…”

“…Previous studies showed the alteration in patellar height after valgus HTO [20][21][22][23][24][25][26]. Scarring and shortening of the patellar ligament may lead to patellofemoral complaints in the valgus HTO patients during the postoperative period and often prevents eversion of the patella, which may require specialized exposure techniques during a subsequent TKA [4,26].…”

Patellaposition und Patellofemoralarthrose nach unikompartimentellem Kniegelenkersatz

“…1 9 Übersicht der Literaturrecherche zur Identifikation von relevanten Studien te eine negative Korrelation zum post operativen "Knee Society Score" aufwie sen. Niedrige präoperative ISWerte kor relierten negativ mit dem postoperativen "Knee Society Score". In einer prospektiven, randomisierten, kontrollierten Studie bestimmten Wea le et al [32] die Länge der Patellarseh ne nach uni (n = 50; Gruppe 1) und tri kompartimenteller (n = 52; Gruppe 2) en doprothetischer Versorgung des Kniege lenks. Bei 7 Fällen mit trikompartimen teller Knieendoprothetik wurde zusätz lich eine laterale Retinakulumspaltung durchgeführt.…”

“…Al lerdings mussten lediglich 2 der 59 Schlit tenprothesen auf eine trikompartimentel le Knieendoprothese aufgrund dieser Be schwerden gewechselt werden [7]. In ei ner ähnlichen Studie berichteten Weale et al [32] über das Fortschreiten einer Patel lofemoralarthrose bei nur 1 von 50 Fällen 5 Jahre nach Implantation einer medialen Schlittenprothese [32].…”

“…Intra und postoperative Fakto ren, wie beispielsweise Kontrakturen vom Narbengewebe, Knochenneubildung, Im mobilisation, patellofemorale Fibrose, Is chämie und Trauma der Patellarsehne werden als mögliche Ursachen genannt [32].…”