Abstract
PurposeThe main purpose of this study was to determine whether there is a correlation between the change of tibial tuberosity-trochlear groove (TT-TG) distance and clinical outcomes after total knee arthroplasty (TKA).MethodsA total of 52 knees undergoing TKA due to primary osteoarthritis were included in this retrospective study. All patients had pre- and postoperative CT scans. TT-TG distance was measured by two independent observers and the following alignment parameters were measured: hip-knee ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA), and posterior condylar angle (PCA). Clinical outcome was assessed using Knee Society Score (KSS) pre- and post-operatively and at a minimum of 12-month follow-up. Evidence of AKP was noted from follow-up reports. Pre- and postoperative scores were compared using a paired Student t-test. Pearson correlations were calculated to assess the influence of TT-TG on clinical outcome and of alignment parameters on the change in TT-TG. TT-TG between patients with and without AKP was compared using unpaired Student’s t-test (p < 0.05).ResultsNeither the absolute postoperative TT-TG nor the amount of change in TT-TG correlated with the post-operative KSS or the change in KSS. Post-operative TT-TG and change in TT-TG did not differ significantly between patients with and patients without AKP. Only the change in FMA showed a correlation with the change in TT-TG (p = 0.01, r = 0.36).ConclusionDespite a missing correlation between outcomes and TT-TG distance in this study, excessive TT-TG distance should be avoided. Furthermore, surgeons need to be aware that changes in femoral joint line orientation might affect TT-TG distance.
Highlights
Patellofemoral problems are a common reason for dissatisfaction in total knee arthroplasty (TKA) patients
The hospital database was searched for patients meeting the following inclusion criteria: (i) received a TKA as treatment for primary knee osteoarthritis between 2009 and 2014, (ii) pre- and postop CT scans available according to the imperial knee protocol [9], (iii) available knee society scores pre-operatively and at minimum one year post-operatively
The main finding of this study is that tuberosity-trochlear groove (TT-TG) distances did not have an influence on clinical outcome after TKA, and we must reject our first hypothesis (1a, 1b, 2c)
Summary
Patellofemoral problems are a common reason for dissatisfaction in total knee arthroplasty (TKA) patients. The tibial tuberosity-trochlear groove (TT-TG) distance is a useful tool in the assessment of young patients with patellofemoral problems [4]. In these patients, a TT-TG distance greater 12 mm is considered “abnormal” and greater than 15 mm “pathological” [5]. There is only a paucity of studies, which assessed TT-TG distances in osteoarthritic (OA) knees or patients undergoing total knee arthroplasty (TKA). These studies reported abnormal or even pathological TT-TG distance in a
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