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The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 10 | Pages 1348 - 1354
1 Oct 2011
Vanbiervliet J Bellemans J Verlinden C Luyckx J Labey L Innocenti B Vandenneucker H

Complications involving the patellofemoral joint, caused by malrotation of the femoral component during total knee replacement, are an important cause of persistent pain and failure leading to revision surgery. The aim of this study was to determine and quantify the influence of femoral component malrotation on patellofemoral wear, and to determine whether or not there is a difference in the rate of wear of the patellar component when articulated against oxidised zirconium (OxZr) and cobalt-chrome (CoCr) components. An in vitro method was used to simulate patellar maltracking for both materials. Both rates of wear and changes in height on the patellar articular surface were measured. The mean rates of wear measured were very small compared to standard tibiofemoral wear rates. When data for each femoral component material were pooled, the mean rate of wear was 0.19 mm3/Mcycle (sd 0.21) for OxZr and 0.34 mm3/Mcycle (sd 0.335) for CoCr. The largest change in height on each patella varied from -0.05 mm to -0.33 mm over the different configurations.

The results suggest that patellar maltracking due to an internally rotated femoral component leads to an increased mean patellar wear. Although not statistically significant, the mean wear production may be lower for OxZr than for CoCr components.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_13 | Pages 31 - 31
7 Aug 2023
Myatt D Marshall M Ankers T Robb C
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Abstract. Unicompartment knee replacement (UKR) has been an effective treatment of isolated medial compartment osteoarthritis (OA). There has been several studies which suggest that patellofemoral (PFJ) wear may not be a relative contraindication for UKR with no statistical difference in failure rates. There is currently conflicting evidence on the role of BMI. We will review if BMI and PFJ wear impacts on the post operative functional scores following UKR. A retrospective review of a prospectively collected database was performed. Data was collected between 26/6/2014 and 25/8/2022. 159 UKR procedures were identified. BMI and PFJ cartilage wear were collected. Oxford knee scores (OKS) were collected at > 2 years. PFJ wear was split into International Cartilage Research Society (ICRS) grades I&II and III&IV. 159 UKR procedures were identified, of these 115 had 2 year follow up. There were 77 who had OKS recorded at 2 years. For PFJ wear there was no statistical difference in the median OKS at 2 years 45 vs 43.5 (p=0.408). Assessing the BMI the median was 29kg/m. 2. , range 20–43kg/m. 2. Spearman's rank was performed to assess the correlation between BMI and >2 year OKS, this demonstrated a moderately negative correlation p(df)=−0.339 (CI 95% −0.538, −0.104) p=0.004. There is no statistically significant difference in >2 year OKS following UKR regardless of PFJ wear. There is a moderately negative correlation between BMI and >2 year OKS which was significant p=0.004. Therefore BMI is a more important consideration when counselling patients for UKR


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XL | Pages 99 - 99
1 Sep 2012
Luyckx J Verlinden C Vanbiervliet J Labey L Innocenti B Leuven J Vandenneucker H
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Introduction. Malrotation of the femoral component is a cause of patellofemoral maltracking after TKA. Its precise effect on the patellofemoral (PF) mechanics has not been well quantified. The aim of this study was to investigate the effect of malrotation of the femoral component on PF initial contact area, initial contact pressure and wear after 4 million full gait cycles in TKA using a knee simulator. Moreover, the influence of the counterface material (CoCr or OxZr) on PF wear was also investigated. Materials & Methods. Femoral components (FCs) were cemented onto specially designed fixtures, allowing positioning of the FC in different angles of axial rotation. Patellar buttons and FCs were then mounted in a Prosim knee simulator. Patellofemoral contact mechanics. Seven axial rotation configurations were tested: neutral (FC parallel to the epicondylar axis), 2.5° endo- and exorotation, 5° endo- and exorotation and 7.5° endo- and exorotation. Patellar contact location, contact area and contact pressure were measured dynamically during 20 gait cycles with a Tekscan sensor covering the patella collecting data at a rate of 100 frames per second. Patellofemoral wear. For three alignments (neutral, 5° endo- and exorotation), a PF wear test of 4 million cycles in bovine serum (diluted to 40%) was done with three CoCr and three OxZr components on conventional ultra-high molecular weight polyethylene (UHMWPE, density: 0.93mg/mm. 3. ). Every 0.5 million cycles the test lubricant was replaced, the patellar samples were cleaned and dried and polyethylene wear was measured gravimetrically. A linear regression model was used to calculate the wear rate of each patellar sample. Aggregate wear rates were determined for each test condition by pooling the measurements of all three patellar samples. Results. For all six endorotation and exorotation configurations, the contact area was significantly lower and the contact pressure significantly higher than the neutral position (p < 0.001, Figs 1 and 2). In the patellofemoral wear test, the highest average wear rate was found in the group of endorotated CoCr femoral components (0.54 mm. 3. /Mcycle), but this is still only 11% of a typical tibiofemoral wear rate with the same CoCr component (5 mm. 3. /Mcycle). The following trends in the average wear rates could be observed: the average wear rate for CoCr (0.34 mm. 3. /Mcycle) was higher than for OxZr (0.19 mm. 3. /Mcycle) and the average wear rate for 5° endorotation (0.35 mm. 3. /Mcycle) was higher than for 5° exorotation (0.21 mm. 3. /Mcycle) and neutral alignment (0.23 mm. 3. /Mcycle) (Figs 3 and 4). None of these differences reached statistical significance (p=0.05), though. Discussion. Our results indicate that both internally and externally malrotated femoral components significantly decrease contact areas and significantly increase contact pressures in the patellofemoral joint. These significant changes in contact pressure didn't translate in significant changes in wear, however. Overall, patellofemoral wear is very small compared to tibiofemoral wear, in all the configurations that we investigated. Based on our results, we can conclude that clinical problems with patellar maltracking after femoral component malrotation seem not to be related to increased wear, but rather to pain and patellar instability


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 12 | Pages 1679 - 1679
1 Dec 2011
Scott J

J. Vanbiervliet, J. Bellemans, C. Verlinden, J.-P. Luyckx, L. Labey, B. Innocenti, H. Vandenneucker. The influence of malrotation and femoral component material on patellofemoral wear during gait. J Bone Joint Surg Br 2011 93-B: 1348-1354


Bone & Joint 360
Vol. 9, Issue 6 | Pages 18 - 21
1 Dec 2020


The Bone & Joint Journal
Vol. 102-B, Issue 6 | Pages 727 - 735
1 Jun 2020
Burger JA Dooley MS Kleeblad LJ Zuiderbaan HA Pearle AD

Aims

It remains controversial whether patellofemoral joint pathology is a contraindication to lateral unicompartmental knee arthroplasty (UKA). This study aimed to evaluate the effect of preoperative radiological degenerative changes and alignment on patient-reported outcome scores (PROMs) after lateral UKA. Secondarily, the influence of lateral UKA on the alignment of the patellofemoral joint was studied.

Methods

A consecutive series of patients who underwent robotic arm-assisted fixed-bearing lateral UKA with at least two-year follow-up were retrospectively reviewed. Radiological evaluation was conducted to obtain a Kellgren Lawrence (KL) grade, an Altman score, and alignment measurements for each knee. Postoperative PROMs were assessed using the Kujala (Anterior Knee Pain Scale) score, Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS JR), and satisfaction levels.


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 8 | Pages 1054 - 1059
1 Aug 2011
van Jonbergen HPW Scholtes VAB van Kampen A Poolman RW

The efficacy of circumpatellar electrocautery in reducing the incidence of post-operative anterior knee pain is unknown. We conducted a single-centre, outcome-assessor and patient-blinded, parallel-group, randomised, controlled trial to compare circumpatellar electrocautery with no electrocautery in total knee replacement in the absence of patellar resurfacing. Patients requiring knee replacement for primary osteoarthritis were randomly assigned circumpatellar electrocautery (intervention group) or no electrocautery (control group). The primary outcome measure was the incidence of anterior knee pain. A secondary measure was the standardised clinical and patient-reported outcomes determined by the American Knee Society scores and the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index. A total of 131 knees received circumpatellar electrocautery and 131 had no electrocautery.

The overall incidence of anterior knee pain at follow-up at one year was 26% (20% to 31%), with 19% (12% to 26%) in the intervention group and 32% (24% to 40%) in the control group (p = 0.02). The relative risk reduction from electrocautery was 40% (9% to 61%) and the number needed to treat was 7.7 (4.3 to 41.4). The intervention group had a better mean total WOMAC score at follow-up at one year compared with the control group (16.3 (0 to 77.7) versus 21.6 (0 to 76.7), p = 0.04). The mean post-operative American Knee Society knee scores and function scores were similar in the intervention and control groups (knee score: 92.4 (55 to 100) versus 90.4 (51 to 100), respectively (p = 0.14); function score: 86.5 (15 to 100) versus 84.5 (30 to 100), respectively (p = 0.49)).

Our study suggests that in the absence of patellar resurfacing electrocautery around the margin of the patella improves the outcome of total knee replacement.