Patellofemoral Complications Research Articles

Kinematic alignment adequately restores trochlear anatomy, patellar kinematics and kinetics in total knee arthroplasty: A systematic review.

Patellofemoral pain, maltrackingand instability remain common and challenging complications after total knee arthroplasty. Controversy exists regarding the effect of kinematic alignment on the patellofemoral joint, as it generally leads to more femoral component valgus and internal rotation compared to mechanical alignment. The aim of this systematic review isto thoroughly examine the influence of kinematic alignment on the third space. A systematic search of the Pubmed, Cochraneand Web of Science databases was performed to screen for relevant articles published before 7 April 2024. This led to the final inclusion of 42 articles: 2 cadaveric, 9radiographic, 12 computer simulationand 19 clinical studies. The risk of bias was evaluated with the risk of bias in non-randomised studies - of interventions tool as the lowest level of evidence of the included clinical studies was IV. The effects of kinematic alignment on patellar kinematics and kinetics, trochlear anatomy reconstructionand patellofemoral complication rate were investigated. Kinematic alignment closely restores native patellar kinematics and kinetics,better reproduces native trochlear anatomy than mechanical alignment and leads to a 0%-11.4% incidence of patellofemoral complications. A more valgus joint line of the distal femur can cause lateral trochlear undercoverage and a trochlear angle orientation medial to the quadriceps vector when applying kinematic alignment, both of which can be solved by using an adjusted design with a 20.5° valgus trochlea. Kinematic alignment appears to be a safe strategy for the patellofemoral joint in most knees, provided that certain precautions are taken to minimize the risk of complications. Level IV clinical studies, in vitro research.

Evaluation of the External Rotation of the Femur Component in Functionally Aligned Robotic-Assisted Total Knee Arthroplasty.

Background The conventional total knee arthroplasty (TKA) for grade 4 knee arthritis lacks individualized strategies for determining femur component rotation, contributing to suboptimal clinical outcomes and heightened patient dissatisfaction. Methods One hundred consecutive active robotic-assisted TKA (RA-TKA) patients were retrospectively evaluated. The control group is the patients undergoing conventional TKA for grade 4 arthritis of the knee joint, where the femoral component is placed in a fixed 3-degreeexternal rotation. The study aimed to explore the relationships between the posterior femoral axis of the functionally aligned TKA (FAA), the trans-epicondylar axis (TEA), and the posterior condylar axis (PCA). Specifically, it investigated whether there is a statistically significant difference in femoral component rotation between the functionally aligned TKA (FTKA) and the conventional 3-degrees of external rotation of the femoral component used in traditional TKA (C-TKA). Internal rotation is indicated by a negative value for the femur component. A student's t-test was employed to compare mean rotation values between FTKA and C-TKA, with a p-value below 0.05 considered statistically significant. Results A total of 100 patients (male: female, 11:89) were studied. The FAA was externally rotated in relation to the TEA (mean 1.451°, SD 1.023°, p-value <0.0001). As regards the PCA, the FAA was externally rotated (mean 2.36°, SD 2.221°, p-value 0.0002). These findings demonstrate a statistically significant difference in femoral component rotation between FTKA and C-TKA. Clinically, no patellofemoral complications or premature loosening were observed at one-year follow-up. Conclusion Functional alignment TKA technique resulted in external rotation of the femur component with respect to TEA and PCA. This negates the null hypothesis, indicating a statistically significant difference amongst the femur component rotation implanted according to the FTKA concept with robotic assisted technology and C-TKA.

Differences in Trochlear Morphology of a New Femoral Component Designed for Kinematic Alignment from a Mechanical Alignment Design.

Because kinematic alignment (KA) aligns femoral components in greater valgus and with less external rotation than mechanical alignment (MA), the trochlear groove of an MA design used in KA is medialized, which can lead to complications. Hence, a KA design has emerged. In this study, our primary objective was to quantify differences in trochlear morphology between the KA design and the MA design from which the KA design evolved. The KA and MA designs were aligned in KA on ten 3D femur-cartilage models. Dependent variables describing the morphology of the trochlea along the anterior flange, which extends proximal to the native trochlea, and along the arc length of the native trochlea, were determined, as was flange coverage. Along the anterior flange, the KA groove was significantly lateral proximally by 10 mm and was significantly wider proximally by 5 mm compared to the MA design (p < 0.0001). Along the arc length of the native trochlea, the KA groove was significantly lateral to the MA design by 4.3 mm proximally (p ≤ 0.0001) and was significantly wider proximally by 19 mm than the MA design. The KA design reduced lateral under-coverage of the flange from 4 mm to 2 mm (p < 0.0001). The KA design potentially mitigates risk of patellofemoral complications by lateralizing and widening the groove to avoid medializing the patella for wide variations in the lateral distal femoral angle, and by widening the flange laterally to reduce under-coverage. This information enables clinicians to make informed decisions regarding use of the KA design.

Satisfactory medium- to long-term outcomes of cemented rotating hinge prosthesis in revision total knee arthroplasty.

The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes. A retrospective consecutive study of all patients who underwent a rTKA using the fully cemented SMILES rotating hinge prosthesis between 2005 to 2018. Outcome measures included aseptic loosening, reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both prospectively collected local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Overall, 69 consecutive patients (69 knees) were included with a median age of 78 years (interquartile range 69 to 84), and there were 46 females (66.7%). Indications were septic revisions in 26 (37.7%), and aseptic aetiology in the remining 43 (62.3%). The mean follow-up was 9.7 years (4 to 18), and the overall complication was rate was 7.24%, all with patellofemoral complications. Failure rate with 'any cause revision' was 5.8%. There was one case of aseptic loosening of the femoral component. At ten years, 17/69 patients (24.63%) had died, and implant survivorship was 92.2%. In our experience, the SMILES rotating hinge prosthesis achieves satisfactory long-term outcomes with ten-year implant survivorship of 92.2% and a patellofemoral complication rate of 7.24%.

Patella non-resurfacing in primary total knee arthroplasty provides good functional results-a retrospective review of nine thousand three hundred forty six knees.

Patellar resurfacing has long been a contentious subject in TKA with no consensus and the literature yielding disparate results. The aim of this study was to evaluate the long-term functional outcomes and complications of patients undergoing primary TKA without patellar resurfacing (non-resurfacing). This study retrospectively analysed 9346 patients who underwent primary manual jig-based TKA without patellar resurfacing at a single high-volume arthroplasty centre between 2010 and 2018. Patients with a minimum threeyear follow-up irrespective of disease etiology and implant manufacturer were included in the study. Primary outcome was measured using Oxford knee score and patellofemoral Feller score. Secondary outcomes included determining the incidence of patellofemoral complications and re-operation rates following TKA. A total of 8695 knees were eligible for final evaluation having a mean follow-up of 6.6 years. Mean age of the patients was 62.6 (SD-7.5) years with female predominance of (N-6619, 70.8%). The majority of the patients had primary OA (N-8792, 94.1%) with varus deformity (N-8642, 92.46%). Depuy was the most used manufacturer (n = 2592, 26.4%) with the posterior stabilised (N-4127, 44.2%) design being the most predominant. The mean Feller score of the study population was 24.5 (SD = 3) with a majority of patients having good to excellent outcomes (86.95%, N-8424) and mean Oxford knee score was 36.9 (SD-6.9) with a majority of the patients having an OKS greater than 30 (87.1%, N-8133) with anterior knee pain (AKP) reported in only 4.8% patients (N-418). Most common complications included patellar clunk (N-56, 0.7%), traumatic patellar fractures (N-62, 0.8%), quadriceps tendon tear (N-54, 0.7%) and patellar dislocation (N-4, 0.05%) CONCLUSION: Patellar non-resurfacing has no detrimental impact on functional outcomes and incidence of AKP. We conclude that it is a safe, cost-effective and satisfactory approach in primary TKA with no significant complications.

Extensor Mechanism Centralization Using Autograft Hamstring for Laterally Dislocating Patella.

Patellofemoral complications following total knee arthroplasty (TKA) are some of the most commonly cited complications in the literature, accounting for up to 50% of secondary procedures in the literature. Lateral dislocation of the patella, while rare, is one of many causes of extensor mechanism dysfunction. We sought to evaluate a novel patellar centralization procedure by comparing patients' pre- and postoperative clinical and radiographic data. A retrospective case-series study was performed on 12 patient knees (5 male and 7 female) presenting with ambulatory dysfunction due to laterally dislocating patella. All of the knees had component revision combined with hamstring autograft tendon weave and medial reefing of the retinaculum and vastus medialis. The results revealed reliable stabilization of the patella and improved extensor lag at a mean 2.2±2.2 years' short-term follow-up, which correlated with improved postoperative radiographic measurements. Range of motion in both flexion and extension was improved postoperatively. Improvements in radiographic measures of patellar tilt and patellar displacement were statistically significant, with reductions in the mean patellar tilt from 41.5°±25.9° to 3.9°±13.7° (P=.004), and in the mean patellar displacement from 2.8±2.1 cm to 0.8±0.9 cm (P=.012). Our study findings support the use of the extensor mechanism centralization procedure with autograft hamstring in management of laterally dislocating patella after TKA. [Orthopedics. 2023;46(3):e186-e188.].

3D-printed patient-specific instrumentation decreases the variability of patellar height in total knee arthroplasty.

Three-dimensionally (3D) printed patient-specific instrumentation (PSI) might help in this regard with individual design and more accurate osteotomy, but whether the utility of such instrumentations minimizes the variability of patellar height in total knee arthroplasty (TKA) and the reasons for this effect are unknown. Our aim is to compare and analyze the variability of patellar height with PSI and conventional instrumentation (CI) in TKA. Between March 2018 and November 2021, 215 patients with severe knee osteoarthritis who were treated with primary unilateral TKA were identified for this observational study. The patients were divided into the CI-TKA group and PSI-TKA group according to the osteotomy tools used in TKA. Preoperative and postoperative radiographic parameters including hip-knee-ankle angle (HKA), posterior tibial slope (PTS), Insall-Salvati ratio, modified Caton-Deschamps (mCD) ratio, anterior condylar offset (ACO), and posterior condylar offset (PCO) were evaluated. The groups were similar in patients' demographic data, clinical scores, and radiographic parameters preoperatively. Overall, according to the results of the Insall-Salvati ratio, postoperative patellar height reduction was noted in 140 patients (65.1%). Interestingly, the variability of patellar height was smaller in the PSI-TKA group. Radiographic evaluation revealed that the Insall-Salvati ratio after TKA had a minor change in the PSI-TKA group (p = 0.005). Similarly, the mCD ratio after TKA also had a minor change in the PSI-TKA group (p < 0.001). Compared to those in the CI-TKA group, the ACO (p < 0.001) and PCO (p = 0.011) after TKA had a minor change in the PSI-TKA group, but no minor PTS change (p = 0.951) was achieved in the PSI-TKA group after TKA. However, even with 3D-printed patient-specific instrumentation, there were still significant reductions in patellar height, ACO, PCO, and PTS after TKA (p < 0.001). The variability of patellar height was sufficiently minimized with more accurate anterior and posterior femoral condyle osteotomy when 3D printed PSI was used. Furthermore, there was a trend in over-resection of the femoral anterior and posterior condyle and a marked reduction in PTS during TKA, which could lead to a change in patellar height and might result in more patellofemoral complications following TKA. Level II.

Effect of rotational malalignment of components on functional outcome of total knee arthroplasty: A prospective observational study

Background: Correction of coronal alignment alone may not translate into optimum functional outcome after total knee arthroplasty. Painful knees and patellofemoral complications are quite common after total knee arthroplasty, and rotational malalignment of the prosthetic components may be responsible. Objectives: We conducted a prospective observational study to compare functional outcomes following total knee arthroplasty among subjects with and without rotational malalignment. Methods: We studied 396 patients (contributing 709 knees with Kellgren-Lawrence grade 4 osteoarthritis) undergoing total knee arthroplasty in a tertiary care hospital setting, with 2-3 years of follow-up. Postoperative axial CT scans were obtained to estimate the rotational alignment of femoral and tibial components. External and internal rotation of components was measured with software to estimate combined external rotation, combined internal rotation, or component mismatch, based on which knees were grouped into two cohorts: having rotational malalignment or with normal alignment. Functional outcome was assessed by Knee Society Score, Oxford Knee Score, Knee Society Pain Score, Lower Extremity Functional Scale, and Public Health Questionnaire-9. Results: Normal alignment (combined external rotation < 10 degrees) was observed in 475 knees, while the rest of 234 knees had rotational malalignment in the form of combined external rotation of 10 degree or above, combined internal rotation or component mismatch. A significant difference in outcome scores was found between these two cohorts at the first follow-up itself. Knee Society Pain Score clearly indicated painful knees in the rotational malalignment cohort. Poorer improvement in outcome scores occurred in this cohort, throughout the duration of follow-up. Conclusions: Rotational malalignment of components is almost invariably associated with the poorer outcome of total knee arthroplasty; manifested by anterior knee pain or incomplete functional recovery, compared to the knees with normal alignment.

High ten-year implant survivorship and low patellofemoral complication rate for S-ROM rotating-hinge implants in revision total knee arthroplasty : a single-centre study.

AimsThe aim of this study was to evaluate medium-term outcomes and complications of the S-ROM NOILES Rotating Hinge Knee System (DePuy, USA) in revision total knee arthroplasty (rTKA) at a tertiary unit.MethodsA retrospective consecutive study of all patients who underwent a rTKA using this implant from January 2005 to December 2018. Outcome measures included reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years.ResultsA total of 89 consecutive patients (89 knees) were included with 47 females (52.8%) and a median age of 74 years (interquartile range 66 to 79). The main indications were aseptic loosening with instability (39.4%; n = 35) and infection (37.1%; n = 33) with the majority of patients managed through two-stage approach. The mean follow-up was 7.4 years (2 to 16). The overall rate of reoperation, for any cause, was 10.1% (n = 9) with a rate of implant revision of 6.7% (n = 6). Only two cases required surgery for patellofemoral complications. Kaplan-Meier implant-survivorship analysis was 93.3% at ten years, using revision for any cause as an endpoint.ConclusionThis implant achieved high ten-year survivorship with a low complication rate, particularly patellofemoral complications. These can be avoided by ensuring central patella tracking and appropriate tension of the patellofemoral joint in this posterior hinge design.Cite this article: Bone Jt Open 2022;3(3):205–210.

Evaluation of Patellofemoral Complications by Comparing the Medial Parapatellar and Subvastus Approaches

Total knee arthroplasty (TKA) is considered to be the best method for treating advanced knee osteoarthritis in terms of reducing pain, improving joint functions, and increasing the patient’s quality of life

BILATERAL VARIABILITY OF Q ANGLE IN SYMPTOMATIC UNILATERAL AND SYMPTOMATIC BILATERAL KNEE PAIN IN INDIAN ADULTS OF DECCAN PLATEAU REGION

Objectives: Quadriceps angle (Q angle) is a lonesome clinical measure, appraised as a critical factor for the posture maintenance and knee related complications.The excessive Q angle increases the lateral patellofemoral junction pressure, which have a tendency to add biomechanical stress over the knee, leads to patellofemoral complications. This study was attempted to determine the right and left Q angle variabilitybetween asymptomatic or control (ASY), symptomatic unilateral knee pain (SUKP), and symptomatic bilateral knee pain (SBKP) in people of Deccan plateau in India. Material and methods:The bilateral Q angles were measured by universal goniometer in 235subjectsof both genders including asymptomatic (n=135), symptomatic unilateral knee pain (n=60) and symptomatic bilateral knee pain (n=40), in upright standing position, with relaxed quadriceps and fully extended knee.Subjects with clinically determined anterior knee pain considered as symptomatic. Results: The higher bilateral variability of Q angle was noticed in females than males between asymptomatic and SUKP (-5.920) and SBKP (-4.090) on right side and between asymptomatic and SUKP (-4.980) on left side. There was bilateral significant difference in Mean Q angle between asymptomatic and SUKP, and between asymptomatic and SBKP in both sexes. However, the above difference was statistically not significant between SBKP and SUKP. Conclusion: Moderate Q angle bilateral variability was noticed in symptomatic subjects due to malalignment of limbs by trauma, unilateral stance of limb and other influencing factors.

The Effect of Resistance Training on Lower Extremity Pain, Strength and Kinematical Parameters in Women With Patellofemoral Complications

Purpose: The aim of this study was to evaluate the effect of strengthening the abductor and external rotator of the hip joint muscles on pain, thigh muscle strength, and lower limb kinematics in volleyball players with patellofemoral complications. Methods: Twenty-four volleyball players with patellofemoral pain were randomly divided into the experimental and control groups. The experimental group received three sessions of strengthening exercises for the abductor muscles and external rotators of the hip joint using Traband for eight weeks. The control group received no training intervention. The pain was assessed by visual acuity scale, hip muscle strength by hand dynamometer, and lower limb kinematics using video analysis before and after the intervention. Samples included volleyball players with patellofemoral pain who had pain in one or both knees. If the pain was bilateral, the exercises were performed bilaterally on both lower limbs, but measurements were taken only from the lower extremity, which was most in pain. Analysis of covariance was used by SPSS software for statistical analysis. Results: The results of this study showed that after training, in the experimental group, pain decreased and the strength of the abductor’s muscles and external rotator of the hip joint muscles increased. Knee dynamic valgus and pelvic drop were observed in single-leg squat only in the experimental group. Conclusion: The results showed that the strengthening of the hip joint can decrease the pain of volleyball players with patellofemoral, increase the strength of the muscles and change the kinematics of the lower limbs on the frontal plane, and this can be the mechanism of the effect of this intervention on the symptoms of pain.

EVALUATION OF TIBIAL COMPONENT ROTATION IN PAINFUL TOTAL KNEE ARTHROPLASTIES BY MRI ENHANCED WITH METAL ARTIFACT REDUCTION TECHNIQUE

Background: Tibial component malrotation is one of the commonest causes of pain and stiffness following total knee arthroplasties, however, the assessment of tibial component malrotation on imaging is not clear-cut. The objective of this study was to assess tibial component rotation in cases with pain following total knee replacement using MRI with metal artifact reduction technique. Methods: In 15 consecutive patients presented in our clinic — a high-volume arthroplasty institution — between January 2017 and June 2017 with persistent unexplained moderate to severe pain for at least 6 months following total knee arthroplasties, which were ALL done outside our institution, after exclusion of infection and loosening (tibial or femoral), MRI evaluation of tibial component rotation using metal artifact reduction for orthopedic implants (O-MAR) technique — to improve visualization of soft tissue and bone by reducing artifacts caused by metal implants — was done according to the technique of Berger et al. [Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res 144–153, 1998]. Results: Eleven cases showed an internal rotation of tibial components (73.3%), four cases showed a neutral or external rotation of tibial components (26.6%), however, with the presence of abnormal intraarticular fibrous bands in two of them. Conclusions: Two main conclusions are obtained from this study: Firstly, internal rotation of tibial component must be excluded in all cases of persistent pain following total knee replacement. Secondly, magnetic resonance imaging with the newly developed metal artifact reduction techniques is a very useful tool in evaluating cases of unexplained pain following total knee replacement.

Intraoperative patellar maltracking and postoperative radiographic patellar malalignment were more frequent in cases of complete medial collateral ligament release in cruciate-retaining total knee arthroplasty

BackgroundPatellar maltracking after total knee arthroplasty (TKA) can lead to significant patellofemoral complications such as anterior knee pain, increased component wear, and a higher risk of component loosening, patellar fracture, and instability. This study was to investigate the preoperative and operative variables that significantly affect patellar tracking after cruciate-retaining TKA.MethodsWe studied 142 knee joints in patients who had undergone TKA: the knees were dichotomized based on postoperative patellar tracking, which was evaluated on patellar skyline, axial-projection radiographs: group 1, normal patellar tracking (lateral tilt ≤ 10° and displacement ≤ 3 mm) and group 2, patellar maltracking (lateral tilt > 10° or displacement > 3 mm). The patients’ demographic data and clinical and radiographic measurements obtained before and after surgery were compared between the two groups.ResultsPreoperative lateral patellar displacement was greater (4.1 ± 2.6 mm vs. 6.0 ± 3.5 mm), as was the frequency of medial collateral ligament (MCL) release (3/67 vs. 24/75) in group 2 than in group 1 (p < 0.001 and p < 0.001, respectively). The distal femur was cut in a greater degree of valgus in group 1 than in group 2. (6.3 ± 0.8° vs. 6.0 ± 0.8°) (p = 0.034).ConclusionsComplete release of the MCL during surgery was associated with patellar maltracking (logistic regression: p = 0.005, odds ratio = 20.592). Surgeons should attend to patellar tracking during surgery in medially tight knees.Level of evidenceRetrospective comparative study, level III.

A Right Angle Guide for Distal Tuberosity Osteotomy With Medial Open Wedge High Tibial Osteotomy for Varus Knee Osteoarthritis

Medial open wedge high tibial osteotomy (OWHTO) is usually performed with proximal tuberosity osteotomy or setting the osteotomy line proximal to the tuberosity. However, OWHTO can result in patellofemoral complications due to postoperative patella infera. A new OWHTO technique, biplanar osteotomy with a distal tuberosity osteotomy, was reported in 2004 to prevent postoperative patella infera. To ensure that the 2 osteotomy lines maintain perpendicular, we describe the OWHTO procedure with a distal tuberosity osteotomy technique using a TriS Medial HTO Plate System (Olympus Terumo Biomaterials Corp., Tokyo, Japan) and a right angle guide we developed. In this Technical Note, we describe the procedure and advantages, risks, and limitations, as well as the pearls and pitfalls based on our experience.

Evaluating the “Patella-Friendly” Concept in Total Knee Arthroplasty: A Minimum 15-Year Follow-Up Outcome Study Comparing Constant Radius, Multiradius Cruciate-Retaining, and Nonanatomical Cruciate-Retaining Implants

BackgroundPatella-friendly femoral components were developed in order to reduce anterior knee pain and patellofemoral complications in total knee arthroplasty (TKA), but their effect on long-term outcome is still unclear. MethodsWe retrospectively evaluated prospectively collected data from 3 groups consisting of 100 patients (100 knees in each). In group A, the constant radius a-MP, in group B the multiradius cruciate-retaining Genesis II, and in group C the nonanatomic, multiradius, cruciate-retaining AGC TKA was implanted. Patients of all groups were matched for age, gender, side, body mass index, and length of follow-up. Preoperative and postoperative clinical outcome data in the form of Knee Society System (KSS), Short Form-12, Western Ontario and McMaster University Osteoarthritis Index, and Oxford Knee Score were available at regular intervals for groups A and B. For patients of group C, KSS score data were available at the same time intervals. In all groups, the patellofemoral compartment was assessed using the Clinical Patella Score scale. Anterior knee pain, secondary patella resurfacing, implant failure, and radiological outcome were assessed in patients of all groups. ResultsAt 10-year and 15-year follow-up, patients of group A showed statistically significant (s.s.) higher (all P = .000) KSS values as compared to those of groups B and C. At 15-year follow-up, patients of group B showed s.s. higher (P = .001) KSS values as compared to those of group C. At 10-year and 15-year follow up, patients of group A showed s.s. higher (all P = .00) Western Ontario and McMaster University Osteoarthritis Index and Oxford Knee Score values as compared to those of group B. At 15-year follow-up only, patients of group A showed s.s. higher (P = .00) Short Form-12 (physical) values as compared to those of group B. In terms of Clinical Patella Score, patients in group A had s.s. higher values (P = .05) when compared to those of groups B and C. Anterior knee pain was recorded in 4.4% of TKAs in group A, 7.5% in group B, and 17.2% in group C. One (1.1%) patient in group A, 3 (3.25%) in group B, and 7 (8%) in group C underwent secondary resurfacing. ConclusionAnatomical, patella-friendly, constant radius femoral components outperform others in reducing anterior knee pain and patella complications in TKA in which the patellae are left nonresurfaced.

Condylar constrained knee prosthesis and rotating hinge prosthesis for revision total knee arthroplasty for mechanical failure have not the same indications and same results.

Purpose: This study aimed to evaluate whether there are any differences in outcomes and complication rates between condylar constrained knee (CCK) and rotating hinge knee (RHK) prostheses used for the first revision of total knee arthroplasty (rTKA) after mechanical failure. Methods: Sixty-three consecutive non-septic revisions of posterior stabilized implants using 33 CCK and 30 RHK prostheses were included. Clinical evaluation and revision rate were compared between the two groups at two years minimum follow-up. Results: The CCK group had significantly better clinical outcomes and satisfaction rates compared to patients with RHK (KSS-knee 70.5 versus 60.7 (p < 0.003) and KSS-function 74.9 versus 47.7 (p < 0.004) at 3.7 (2.0–9.4) years mean follow-up. Moreover, the clinical improvement was significantly higher for the CCK group concerning the KSS-Knee (+23.9 vs. +15.2 points, p = 0.03). The postoperative flexion was significantly better in the CCK group compared to the RHK group (115° vs. 103°, p = 0.01). The prosthesis-related complications and the re-revision rate were higher in the RHK group, especially due to patellofemoral complications and mechanical failures. Conclusions: CCK prostheses provided better clinical and functional outcomes and fewer complications than RHK prostheses when used for the first non-septic rTKA. CCK is a safe and effective implant for selected patients, while RHK should be used with caution as a salvage device for complex knee conditions, with particular attention to the balance of the extensor mechanism.

Comparison of Patellofemoral Outcomes between Attune and PFC Sigma Designs: A Prospective Matched-Pair Analysis.

BackgroudAttune (DePuy Synthes) prosthesis was designed to overcome patellofemoral complications associated with PFC Sigma (DePuy Synthes) prosthesis. The aim of our study was to compare the incidence of anterior knee pain (AKP), patellofemoral crepitus (PCr), and functional outcome between them.MethodsThis prospective matched-pair study was conducted between January 2014 and June 2015, during which 75 consecutive Attune total knee arthroplasties (TKAs) were matched with 75 PFC Sigma TKAs based on age, sex, body mass index, pathology, and deformity. A single surgeon performed all the operations with aid of computer navigation, using a posterior-stabilized prosthesis with patellar resurfacing. Outcome was assessed by new Knee Society Score (NKSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. AKP and PCr were assessed by a patient-administered questionnaire till 2 years of follow-up. Three pairs were lost to follow-up and finally 72 pairs were analyzed.ResultsOne patient in each group reported AKP and 1 patient from each group had PCr at 2 years postoperatively. None of these patients required additional surgery. The incidence of lateral retinacular release was higher with PFC Sigma (5/72) than Attune (2/72); however, this was statistically not significant (p = 0.4). The Attune group had a significantly greater range of motion (ROM) at 3 months postoperatively (p = 0.049). At final follow-up, ROM was comparable between two prosthesis designs. NKSS and WOMAC scores were also comparable between the groups.ConclusionsWe observed that both Attune and PFC Sigma had a low and comparable incidence of AKP and PCr up to 2 years of follow-up. The Attune group achieved a significantly greater ROM at 3 months postoperatively. At 2 years of follow-up, both prostheses had excellent and comparable clinical and functional results.

Forensic analysis of retrieved score knees: A failure of fixation?

Background: The SCORE total knee arthroplasty (Amplitude, France) has a deep trochlear groove designed to reduce polyethylene wear, risk of loosening, and patellofemoral complications. In 2014, the AOANJRR reported a higher revision rate when implanted cementless compared to cemented. The aim of the study was to forensically examine retrieved SCORE TKA’s and determine failure modes. Methods: Retrieval analysis was performed at the Centre of Implant Technology and Retrieval Analysis (Royal Perth Hospital). 27 SCORE primary total knee implants from 26 patients requiring revision were forensically analysed for failure mode. Macroscopic examination and quantitative assessment of tissue ingrowth was combined with clinical record findings and radiographic analysis. Statistical analysis was performed. Results: On average the patients were relatively young (mean age 65.5 years) and obese (mean BMI=32.5) with almost equal numbers of male and females and a mean short time of service (2.4 years). The majority of the implants were cementless and without patella resurfacing. Secondary analysis of patient demographics found no difference in age, BMI, gender and activity levels between the patients with loose femoral components and the population as a whole. Radiological analysis revealed an overall satisfactory alignment using the Knee Society TKA Roentgenographic Evaluation and Scoring System. Although six uncemented femoral components (22%) were found grossly loose at time of revision, only one was identified pre-operatively from plain x-rays. Macroscopic analysis confirmed coating delamination and deposition of fine metallic debris on tissue attached to components. Polyethylene inserts had a degree of wear greater than expected with embedded metal debris. Histomorphometric analysis revealed poor bony ingrowth on both uncemented femoral and tibial components. Conclusions: Retrieval analysis revealed a higher than expected rate of cementless femoral loosening in SCORE TKAs. Clinically, surgeons should be aware of patients with this implant presenting with pain that femoral loosening cannot be excluded as a diagnosis by imaging.

Patellar Tilt in Two Modern Total Knee Arthroplasty Systems: A Matched-Cohort Analysis

Background and Hypothesis: Excessive patellar tilt is undesirable in total knee arthroplasty (TKA) and can result in patellofemoral complications and premature failure/wear. Few studies have investigated patellar tilt between TKA systems with different femoral component geometries and bearing articulations. The purpose of this study was to (1) compare patellar tilt between TKA systems with differing femoral component geometries and (2) evaluate related differences in patient-reported outcome measures (PROMS). The study hypothesis was neutral patellar tilt would correlate with improved postoperative PROMS.&#x0D; Experimental Design or Project Methods: 380 symmetric trochlear groove TKAs were matched to 380 asymmetric lateralized trochlear groove TKAs on age, sex, body mass index, and preoperative patellar tilt. All cases were performed by one surgeon between 12/2010 and 10/2018. Patellar tilt (in degrees) was measured by two independent blinded raters on preoperative and 4-week postoperative merchant view radiographs per the modern Knee Society Radiographic Evaluation System. Prospectively collected and validated PROMS including UCLA Activity Level, components of the Knee Society Score, and Likert satisfaction were evaluated at minimum one-year. &#x0D; Results: There were no differences between study cohorts for demographics, covariates, or preoperative patellar tilt (p≥0.479). Asymmetric lateralized trochlear groove TKAs had significantly less postoperative patellar tilt compared with symmetric trochlear groove TKAs (p&lt;0.001). Patellar tilt and femoral implant type had no correlation to pain scores (Knee Society), UCLA Activity Level, or satisfaction (p≥0.138); however, postoperative patellar tilt was significantly less for patients who stated their knee “always” felt normal compared to patients who stated their knee “sometimes” felt normal but not “never” felt normal (p=0.033).&#x0D; Conclusion and Potential Impact: Findings suggest implant type and patellar tilt have minimal effect on overall PROMS. However, minimizing patella maltracking may provide patients with a more normal feeling TKA and could potentially provide long-term benefits of preventing polyethylene wear or other complications leading to premature implant failure.