Aims. It is not clear whether anterior knee pain and osteoarthritis (OA) of the patellofemoral joint (PFJ) are contraindications to medial unicompartmental knee arthroplasty (UKA). Our aim was to investigate the long-term outcome of a consecutive series of patients, some of whom had anterior knee pain and PFJ OA managed with UKA. Patients and Methods. We assessed the ten-year functional outcomes and 15-year implant survival of 805 knees (677 patients) following medial mobile-bearing UKA. The intra-operative status of the PFJ was documented and, with the exception of bone loss with grooving to the lateral side, neither the clinical or radiological state of the PFJ nor the presence of anterior knee pain were considered a contraindication. The impact of radiographic findings and anterior knee pain was studied in a subgroup of 100 knees (91 patients). Results. There was no relationship between functional outcomes, at a mean of ten years, or 15-year implant survival, and pre-operative anterior knee pain, or the presence or degree of cartilage loss documented intra-operatively at the medial patella or trochlea, or radiographic evidence of OA in the medial side of the PFJ. In 6% of cases there was full thickness cartilage loss on the lateral side of the patella. In these cases, the overall ten-year function and 15-year survival was similar to those without cartilage loss; however they had slightly more difficulty with descending stairs. Radiographic signs of OA seen in the lateral part of the PFJ were not associated with a definite compromise in functional outcome or implant survival. Conclusion. Severe damage to the lateral side of the PFJ with bone loss and grooving remains a contraindication to mobile-bearing UKA. Less severe damage to the lateral side of the PFJ and damage to the medial side, however severe, does not compromise the overall function or survival, so should not be considered to be a contraindication. However, if a patient does have full thickness cartilage loss on the lateral side of the PFJ they may have a slight compromise in their ability to descend stairs. Pre-operative anterior knee pain also does not compromise the functional outcome or survival and should not be considered to be a contraindication. Cite this article: Bone Joint J 2017;99-B:632–9

Aims. The aim of this study was to compare the incidence of anterior knee pain after antegrade tibial nailing using suprapatellar and infrapatellar surgical approaches. Patients and Methods. A total of 95 patients with a tibial fracture requiring an intramedullary nail were randomized to treatment using a supra- or infrapatellar approach. Anterior knee pain was assessed at four and six months, and one year postoperatively, using the Aberdeen Weightbearing Test – Knee (AWT-K) score and a visual analogue scale (VAS) score for pain. The AWT-K is an objective patient-reported outcome measure that uses weight transmitted through the knee when kneeling as a surrogate for anterior knee pain. Results. A total of 53 patients were randomized to a suprapatellar approach and 42 to an infrapatellar approach. AWT-K results showed a greater mean proportion of weight transmitted through the injured leg compared with the uninjured leg when kneeling in the suprapatellar group compared with the infrapatellar group at all timepoints at all follow-up visits. This reached significance at four months for all timepoints except 30 seconds. It also reached significance at six months at 0 seconds, and for one year at 60 seconds. Conclusion. The suprapatellar surgical approach for antegrade tibial nailing is associated with less anterior knee pain postoperatively compared with the infrapatellar approach. Cite this article: Bone Joint J 2019;101-B:1138–1143

Excessive foot pronation has been considered to be related to anterior knee pain. We undertook a prospective study to test the hypothesis that exertional anterior knee pain is related to the static and dynamic parameters of foot pronation. Two weeks before beginning basic training lasting for 14 weeks, 473 infantry recruits were enrolled into the study and underwent two-dimensional measurement of their subtalar joint displacement angle during walking on a treadmill. Of the 405 soldiers who finished the training 61 (15%) developed exertional anterior knee pain. No consistent association was found between the incidence of anterior knee pain and any of the parameters of foot pronation. While a statistically significant association was found between anterior knee pain and pronation velocity (left foot, p = 0.05; right foot, p = 0.007), the relationship was contradictory for the right and left foot. Our study does not support the hypothesis that anterior knee pain is related to excessive foot pronation

The purpose of this study was to test the hypothesis that patella alta leads to a less favourable situation in terms of patellofemoral contact force, contact area and contact pressure than the normal patellar position, and thereby gives rise to anterior knee pain. A dynamic knee simulator system based on the Oxford rig and allowing six degrees of freedom was adapted in order to simulate and record the dynamic loads during a knee squat from 30° to 120° flexion under physiological conditions. Five different configurations were studied, with variable predetermined patellar heights. The patellofemoral contact force increased with increasing knee flexion until contact occurred between the quadriceps tendon and the femoral trochlea, inducing load sharing. Patella alta caused a delay of this contact until deeper flexion. As a consequence, the maximal patellofemoral contact force and contact pressure increased significantly with increasing patellar height (p < 0.01). Patella alta was associated with the highest maximal patellofemoral contact force and contact pressure. When averaged across all flexion angles, a normal patellar position was associated with the lowest contact pressures. Our results indicate that there is a biomechanical reason for anterior knee pain in patients with patella alta

Anterior knee pain in adolescents is generally recognised as a common but benign self-limiting condition. Although many operative procedures for its treatment have been proposed, there is little statistical evidence that they are more effective than expectant management. A group of 54 adolescent girls has been followed for two to eight years from presentation with anterior knee pain. Although some pain persisted in the majority, in many the symptoms declined in severity. This study provides a baseline for comparison with the results of operative intervention; it is suggested that surgical treatment is unproven and unnecessary

We assessed patellofemoral joint function by combining the measurement of maximal isometric extensor torque at the knee with clinical and radiological measurements in order to calculate the patellofemoral contact force. Eighteen volunteers established the normal ranges of results and the reliability of the system. Of the 39 patients with a variety of knee problems, 29 had anterior knee pain, and all had a subsequent arthroscopy. Patients with anterior knee pain and lesions in the patellar cartilage had significantly reduced isometric contact forces, but those with normal patellofemoral cartilage had normal contact forces. Our method may be useful in providing an objective assessment of anterior knee pain and a quantitative means of monitoring its treatment

Postoperative anterior knee pain was evaluated in a consecutive series of 138 knees in 108 patients with rheumatoid arthritis treated by total knee replacement with Mark I Insall-Burstein prostheses. No knee had primary patellar resurfacing, and in the 119 knees followed up for a mean of 63.9 months, none had secondary resurfacing. Anterior knee pain was absent in 87 knees (73%), mild in 16 (13.5%) and moderate or severe in 16 (13.5%). The height of the patella above the prosthetic joint line was the only variable which was directly related to the incidence of anterior knee pain. The sensitivity and specificity of patellar height measurements for identifying patients with or without pain were derived. From these data, a selective policy of resurfacing the patella in those at risk was adopted. Choosing a patellar height of 15 mm or less, patellar resurfacing could be avoided in 80% of patients likely to have no pain, and the patella could be resurfaced in 65% of those likely to have anterior knee pain

Out of a total of 623 patients who, over a ten-year period, underwent primary total knee replacement (TKR) without patellar resurfacing, 20 underwent secondary resurfacing for chronic anterior knee pain. They were evaluated pre- and postoperatively using the clinical and radiological American Knee Society score. The mean follow-up was 36.1 months (12 to 104). The mean knee score improved from 46.7 to 62.2 points and the mean functional score from 44.7 to 52.2 points. Only 44.4% of the patients, however, reported some improvement; the remainder reported no change or deterioration. The radiographic alignment of the TKR did not influence the outcome of secondary resurfacing of the patella. Complications were noted in six of the 20 patients including fracture and instability of the patella and loss of movement. Anterior knee pain after TKR remains difficult to manage. Secondary resurfacing of the patella is not advocated in all patients since it may increase patient dissatisfaction and hasten revision

Aims. This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates. Methods. A systematic review of MEDLINE, PubMed, and Google Scholar was performed to identify randomized controlled trials (RCTs) according to search criteria. Search terms used included: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, and patellar retaining. RCTs that compared patellar resurfacing versus unresurfaced in primary TKA were included for further analysis. Studies were evaluated using the Scottish Intercollegiate Guidelines Network assessment tool for quality and minimization of bias. Data were synthesized and meta-analysis performed. Results. There were 4,135 TKAs (2,068 resurfaced and 2,027 unresurfaced) identified in 35 separate cohorts from 33 peer-reviewed studies. Anterior knee pain rates were significantly higher in unresurfaced knees overall (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.20 to 2.83; p = 0.006) but more specifically associated with CR implants (OR 1.95; 95% CI 1.0 to 3.52; p = 0.030). There was a significantly better Knee Society function score (mean difference (MD) -1.98; 95% CI -1.1 to -2.84; p < 0.001) and Oxford Knee Score (MD -2.24; 95% CI -0.07 to -4.41; p = 0.040) for PS implants when patellar resurfacing was performed, but these differences did not exceed the minimal clinically important difference for these scores. There were no significant differences in complication rates or infection rates according to implant design. There was an overall significantly higher reoperation rate for unresurfaced TKA (OR 1.46 (95% CI 1.04 to 2.06); p = 0.030) but there was no difference between PS or CR TKA. Conclusion. Patellar resurfacing, when performed with CR implants, resulted in lower rates of anterior knee pain and, when used with a PS implant, yielded better knee-specific functional outcomes. Patellar resurfacing was associated with a lower risk of reoperation overall, but implant type did not influence this. Cite this article: Bone Joint J 2023;105-B(6):622–634

Anterior knee pain and/or radiological evidence of degeneration of the patellofemoral joint are considered to be contraindications to unicompartmental knee replacement. The aim of this study was to determine whether this is the case. Between January 2000 and September 2003, in 100 knees (91 patients) in which Oxford unicompartmental knee replacements were undertaken for anteromedial osteoarthritis, pre-operative anterior knee pain and the radiological status of the patellofemoral joint were defined using the Altman and Ahlback systems. Outcome was evaluated at two years with the Oxford knee score and the American Knee Society score. Pre-operatively 54 knees (54%) had anterior knee pain. The clinical outcome was independent of the presence or absence of pre-operative anterior knee pain. Degenerative changes of the patellofemoral joint were seen in 54 patients (54%) on the skyline radiographs, including ten knees (10%) with joint space obliteration. Patients with medial patellofemoral degeneration had a similar outcome to those without. For some outcome measures patients with lateral patellofemoral degeneration had a worse score than those without, but these patients still had a good outcome, with a mean Oxford knee score of 37.6 (SD 9.5). These results show that neither anterior knee pain nor radiologically-demonstrated medial patellofemoral joint degeneration should be considered a contraindication to Oxford unicompartmental knee replacement. With lateral patellofemoral degeneration the situation is less well defined and caution should be observed

Aims. Patellofemoral problems are a common complication of total knee arthroplasty. A high compressive force across the patellofemoral joint may affect patient-reported outcome. However, the relationship between patient-reported outcome and the intraoperative patellofemoral contact force has not been investigated. The purpose of this study was to determine whether or not a high intraoperative patellofemoral compressive force affects patient-reported outcome. Patients and Methods. This prospective study included 42 patients (42 knees) with varus-type osteoarthritis who underwent a bi-cruciate stabilized total knee arthroplasty and in whom the planned alignment was confirmed on 3D CT. Of the 42 patients, 36 were women and six were men. Their mean age was 72.3 years (61 to 87) and their mean body mass index (BMI) was 24.4 kg/m2 (18.2 to 34.3). After implantation of the femoral and tibial components, the compressive force across the patellofemoral joint was measured at 10°, 30°, 60°, 90°, 120°, and 140° of flexion using a load cell (Kyowa Electronic Instruments Co., Ltd., Tokyo, Japan) manufactured in the same shape as the patellar implant. Multiple regression analyses were conducted to investigate the relationship between intraoperative patellofemoral compressive force and patient-reported outcome two years after implantation. Results. No patient had anterior knee pain after total knee arthroplasty. The compressive force across the patellofemoral joint at 140°of flexion was negatively correlated with patient satisfaction (R2 = 0.458; β = –0.706; p = 0. 041) and Forgotten Joint Score-12 (FJS-12; R2= .378; β = –0.636; p = 0. 036). The compressive force across the patellofemoral joint at 60° of flexion was negatively correlated with the patella score (R2 = 0.417; β = –0.688; p = 0. 046). Conclusion. Patient satisfaction, FJS-12, and patella score were affected by the patellofemoral compressive force at 60° and 140° of flexion. Reduction of the patellofemoral compressive forces at 60° and 140° of flexion angle during total knee arthroplasty may improve patient-reported outcome, but has no effect on anterior knee pain

The incidence of anterior knee pain following total knee replacement (TKR) is reported to be as high as 49%. The source of the pain is poorly understood but the soft tissues around the patella have been implicated. In theory circumferential electrocautery denervates the patella thereby reducing efferent pain signals. However, there is mixed evidence that this practice translates into improved outcomes. We aimed to investigate the clinical effect of intra-operative circumpatellar electrocautery in patients undergoing TKR using the LCS mobile bearing or Kinemax fixed bearing TKR. A total of 200 patients were randomised to receive either circumpatellar electrocautery (diathermy) or not (control). Patients were assessed by visual analogue scale (VAS) for anterior knee pain and Oxford knee score (OKS) pre-operatively and three months, six months and one year post-operatively. Patients and assessors were blinded. There were 91 patients in the diathermy group and 94 in the control. The mean VAS improvement at one year was 3.9 in both groups (control; -10 to 6, diathermy;. -9 to 8, p < 0.001 in both cases, paired, two-tailed t-test). There was no significant difference in VAS between the groups at any other time. The mean OKS improvement was 17.7 points (0 to 34) in the intervention group and 16.6 (0 to 42) points in the control (p = 0.36). There was no significant difference between the two groups in OKS at any other time. We found no relevant effect of patellar electrocautery on either VAS anterior knee pain or OKS for patients undergoing LCS and Kinemax TKR

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

We have examined the differences in clinical outcome of total knee replacement (TKR) with and without patellar resurfacing in a prospective, randomised study of 181 osteoarthritic knees in 142 patients using the Profix total knee system which has a femoral component with features considered to be anatomical and a domed patellar implant. The procedures were carried out between February 1998 and November 2002. A total of 159 TKRs in 142 patients were available for review at a mean of four years (3 to 7). The patients and the clinical evaluator were blinded in this prospective study. Evaluation was undertaken annually by an independent observer using the knee pain scale and the Knee Society clinical rating system. Specific evaluation of anterior knee pain, stair-climbing and rising from a seated to a standing position was also undertaken. No benefit was shown of TKR with patellar resurfacing over that without resurfacing with respect to any of the measured outcomes. In 22 of 73 knees (30.1%) with and 18 of 86 knees (20.9%) without patellar resurfacing there was some degree of anterior knee pain (p = 0.183). No revisions related to the patellofemoral joint were performed in either group. Only one TKR in each group underwent a re-operation related to the patellofemoral joint. A significant association between knee flexion contracture and anterior knee pain was observed in those knees with patellar resurfacing (p = 0.006)

Aims. The aims of this study were to investigate the ability to kneel after total knee arthroplasty (TKA) without patellar resurfacing, and its effect on patient-reported outcome measures (PROMs). Secondary aims included identifying which kneeling positions were most important to patients, and the influence of radiological parameters on the ability to kneel before and after TKA. Methods. This prospective longitudinal study involved 209 patients who underwent single radius cruciate-retaining TKA without patellar resurfacing. Preoperative EuroQol five-dimension questionnaire (EQ-5D), Oxford Knee Score (OKS), and the ability to achieve four kneeling positions were assessed including a single leg kneel, a double leg kneel, a high-flexion kneel, and a praying position. The severity of radiological osteoarthritis (OA) was graded and the pattern of OA was recorded intraoperatively. The flexion of the femoral component, posterior condylar offset, and anterior femoral offset were measured radiologically. At two to four years postoperatively, 151 patients with a mean age of 70.0 years (SD 9.44) were included. Their mean BMI was 30.4 kg/m. 2. (SD 5.36) and 60 were male (40%). They completed EQ-5D, OKS, and Kujala scores, assessments of the ability to kneel, and a visual analogue scale for anterior knee pain and satisfaction. Results. The ability to kneel in the four positions improved in between 29 (19%) and 53 patients (35%) after TKA, but declined in between 35 (23%) and 46 patients (30%). Single-leg kneeling was most important to patients. After TKA, 62 patients (41%) were unable to achieve a single-leg kneel, 76 (50%) were unable to achieve a double-leg kneel, 102 (68%) were unable to achieve a high-flexion kneel and 61 (40%) were unable to achieve a praying position. Posterolateral cartilage loss significantly affected preoperative deep flexion kneeling (p = 0.019). A postoperative inability to kneel was significantly associated with worse OKS, Kujala scores, and satisfaction (p < 0.05). Multivariable regression analysis identified significant independent associations with the ability to kneel after TKA (p < 0.05): better preoperative EQ-5D and flexion of the femoral component for single-leg kneeling; the ability to achieve it preoperatively and flexion of the femoral component for double-leg kneeling; male sex for high-flexion kneeling; and the ability to achieve it preoperatively, anterior femoral offset, and patellar cartilage loss for the praying position. Conclusion. The ability to kneel was important to patients and significantly influenced knee-specific PROMs, but was poorly restored by TKA with equal chances of improvement or decline. Cite this article: Bone Joint J 2021;103-B(9):1514–1525

Patella subluxation assessed on dynamic MRI has previously been shown to be associated with anterior knee pain. In this MRI study of 60 patients we investigated the relationship between subluxation and multiple bony, cartilaginous and soft-tissue factors that might predispose to subluxation using discriminant function analysis. Patella engagement (% of patella cartilage overlapping with trochlea cartilage) had the strongest relationship with subluxation. Patellae with > 30% engagement tended not to sublux; those with < 30% tended to sublux. Other factors that were associated with subluxation included the tibial tubercle-trochlea notch distance, vastus medialis obliquus distance from patella, patella alta, and the bony and cartilaginous sulcus angles in the superior part of the trochlea. No relationship was found between subluxation and sulcus angles for cartilage and bone in the middle and lower part of the trochlea, cartilage thicknesses and Wiberg classification of the patella. This study indicates that patella engagement is a key factor associated with patellar subluxation. This suggests that in patients with anterior knee pain with subluxation, resistant to conservative management, surgery directed towards improving patella engagement should be considered. A clinical trial is necessary to test this hypothesis

The management of the patella during total knee replacement is controversial. In some studies the absence of patellar resurfacing results in residual anterior knee pain in over 10% of patients. One form of treatment which may be used in an endeavour to reduce this is circumferential patellar rim electrocautery. This is believed to partially denervate the patella. However, there is no evidence of the efficacy of this procedure, nor do we know if it results in harm. A retrospective comparative cohort study was performed of 192 patients who had undergone a primary total knee replacement with the porous coated Low Contact Stress rotating platform prosthesis without patellar resurfacing between 2003 and 2007. In 98 patients circumferential electrocautery of the patellar rim was performed and in 94 patients it was not. The two groups were matched for gender and age. The general Oxford Knee Score and the more specific patellar score for anterior knee pain were used to assess patient outcomes a minimum of two years post-operatively. No statistically significant differences were noted between the groups for either scoring system (p = 0.41 and p = 0.87, respectively). Electrocautery of the patella rim did not improve the outcome scores after primary total knee replacement in our patients

We investigated the association between the radiological findings and the symptoms arising from the patellofemoral joint in advanced osteoarthritis (OA) of the knee. Four radiological features, joint space narrowing, osteophyte formation, translation of the patella and focal attrition were assessed in 151 consecutive osteoarthritic knees in 107 patients undergoing total knee replacement. The symptoms which were assessed included anterior knee pain which was scored, the ability to rise from a chair and climb stairs, and quadriceps weakness. Among the radiological features, only patellar translation and obliteration of the joint space had a statistically significant association with anterior knee pain (odds ratio (OR) 4.85; 95% confidence interval (CI) 1.83 to 12.88 and OR 11.23; 95% CI 2.44 to 51.62) respectively. Patellar translation had a statistically significant association with difficulty in rising from a chair (OR 9.06; 95% CI 1.75 to 45.11). Other radiological features, including osteophytes, joint space narrowing, and focal attrition had no significant association. Our study indicates that the radiological findings of patellar translation and significant loss of cartilage are predictive of patellofemoral symptoms and functional limitation in advanced OA of the knee

Mechanical abnormalities of the patellofemoral joint are among the many causes that have been suggested for adolescent knee pain. This study seeks to identify these factors. Measurements of joint mobility and lower limb morphology were made on 446 pupils at a comprehensive school, 136 of whom had suffered knee pain in the previous year. The pupils with symptoms enjoyed sporting activities significantly more than their symptom-free contemporaries. Joint mobility, the Q-angle, genu valgum and anteversion of the femoral neck were not significantly different between those pupils with and those without anterior knee pain. Data on lower limb morphology of normal adolescents are presented. Examination of 52 hospital outpatients aged 13 to 36 years with anterior knee pain produced results comparable with those for the pupils. It is concluded that chronic overloading, rather than faulty mechanics, is the dominant factor in the genesis of anterior knee pain in adolescent patients

Aims. Medial unicompartmental knee arthroplasty (UKA) is associated with successful outcomes in carefully selected patient cohorts. We hypothesised that severity and location of patellofemoral cartilage lesions significantly influences functional outcome after Oxford medial compartmental knee arthroplasty. Patients and Methods. We reviewed 100 consecutive UKAs at minimum eight-year follow-up (96 to 132). A single surgeon performed all procedures. Patients were selected based on clinical and plain radiographic assessment. All patients had end-stage medial compartment osteoarthritis (OA) with sparing of the lateral compartment and intact anterior cruciate ligaments. None of the patients had end-stage patellofemoral OA, but patients with anterior knee pain or partial thickness chondral loss were not excluded. There were 57 male and 43 female patients. The mean age at surgery was 69 years (41 to 82). At surgery the joint was carefully inspected for patellofemoral chondral loss and this was documented based on severity of cartilage loss (0 to 4 Outerbridge grading) and topographic location (medial, lateral, central, and superior or inferior). Functional scores collected included Oxford Knee Score (OKS), patient satisfaction scale and University College Hospital (UCH) knee score. Intraclass correlation was used to compare chondral damage to outcomes. Results. All patients documented significant improvement in pain and improved functional scores at mid-term follow-up. There were four revisions (mean 2.9 years, 2 to 4; standard deviation (. sd). 0.9) in this cohort, three for tibial loosening and one for femoral loosening. There was one infection that was treated with debridement and insert exchange. The mean OKS improved from 23.2 (. sd. 7.1) to 39.1 (. sd. 6.9); p < 0.001. The cohort with central and lateral grade 3 patellofemoral OA documented lower mean satisfaction with pain (90, . sd.  11.8) and function (87.5, . sd. 10.3) on the patient satisfaction scale. On the UCH scale, patients reported significantly decreased mean overall scores (7.3, . sd. 1.2 vs 9, . sd. 2.3) as well as stair climb task (3.5, . sd. 0.3 vs 5, . sd. 0.1) when cartilage lesions were located centrally or laterally on the PFJ. Patients with medial chondral PFJ lesions behave similar to patients with no chondral lesions. Conclusion. Topographical location and severity of cartilage damage of the patella can significantly influence function after successful Oxford medial UKA. Surgeons should factor this in when making their operative decision, and undertake to counsel patients appropriately. Cite this article: Bone Joint J 2016;98-B(10 Suppl B):11–15

We sought to determine the degree of correlation between the condition of the patellar articular cartilage and patellofemoral symptoms and function in osteoarthritic patients undergoing total knee arthroplasty. The depth of the osteoarthritic lesion, as graded by the Outerbridge classification and its size and location were assessed to determine the condition of the patellar cartilage in 80 consecutive osteoarthritic knees undergoing total knee arthroplasty. The association between the condition of the cartilage and patellofemoral symptoms and function was investigated by correlation analysis. The depth and size of the lesion had a significant but weak correlation with anterior knee pain (r = −0.300 and −0.289; p = 0.007 and 0.009, respectively), whereas location had no significant association (p > 0.05). None had a significant association with patellofemoral functional parameters (chair-rising, stair-climbing, and quadriceps power) (p > 0.05). Our study indicates that patellofemoral symptoms and function are not completely determined by the condition of the cartilage. Caution should be taken when the symptoms and functional limitations are attributed to a lesion in the patellofemoral joint in making a decision regarding patellar resurfacing in total knee arthroplasty

Patellofemoral complications are common after total knee replacement (TKR). Leaving the patellar unsurfaced after TKR may lead to complications such as anterior knee pain, and re-operation to surface it. Complications after patellar resurfacing include patellar fracture, aseptic loosening, patellar instability, polyethylene wear, patellar clunk and osteonecrosis. Historically, patellar complications account for one of the larger proportions of causes of failure in TKR, however, with contemporary implant designs, complication rates have decreased. Most remaining failures relate to patellofemoral tracking. Understanding the causes of patellofemoral maltracking is essential to prevent these complications as well as manage them when they occur. Cite this article: Bone Joint J 2014;96-B(11 Suppl A):84–6

We describe 83 knees (69 patients) which had had patellectomy for anterior knee pain (52), patellofemoral osteoarthritis (25) or comminuted fractures (6) between 1942 and 1978. The patients were questioned about their symptoms and the function of the operated knee 14 to 50 years after operation. In the group with anterior knee pain, 76% achieved good results and were satisfied with the operation. Only 54% of the osteoarthritis group had satisfactory relief of pain and most had progressive deterioration of function. Sixteen patients who had had unilateral patellectomy were assessed by dynamometry, ultrasound and radiography. The average quadriceps muscle power was 60% of that on the normal side although two patients had stronger muscles in their operated than in their unoperated legs

In the absence of patellar resurfacing, we have previously shown that the use of electrocautery around the margin of the patella improved the one-year clinical outcome of total knee replacement (TKR). In this prospective randomised study we compared the mean 3.7 year (1.1 to 4.2) clinical outcomes of 300 TKRs performed with and without electrocautery of the patellar rim: this is an update of a previous report. The overall prevalence of anterior knee pain was 32% (95% confidence intervals [CI] 26 to 39), and 26% (95% CI 18 to 35) in the intervention group compared with 38% (95% CI 29 to 48) in the control group (chi-squared test; p = 0.06). The overall prevalence of anterior knee pain remained unchanged between the one-year and 3.7 year follow-up (chi-squared test; p = 0.12). The mean total Western Ontario McMasters Universities Osteoarthritis Indices and the American Knee Society knee and function scores at 3.7 years’ follow-up were similar in the intervention and control groups (repeated measures analysis of variance p = 0.43, p = 0.09 and p = 0.59, respectively). There were no complications. A total of ten patients (intervention group three, control group seven) required secondary patellar resurfacing after the first year. Our study suggests that the improved clinical outcome with electrocautery denervation compared with no electrocautery is not maintained at a mean of 3.7 years’ follow-up. Cite this article: Bone Joint J 2014;96-B:473–8

An abnormal lateral position of the tibial tuberosity causes distal malalignment of the extensor mechanism of the knee and can lead to lateral tracking of the patella causing anterior knee pain or objective patellar instability, characterised by recurrent dislocation. Computer tomography is used for a precise pre-operative assessment of the tibial tubercle-trochlear groove distance. A distance of more than 15 mm is considered to be pathological and an indication for surgery in symptomatic patients. In a prospective study we performed a subtle transfer of the tibial tuberosity according to the information gained from the pre-operative CT scan. This method was applied to two groups of patients, those with painful lateral tracking of the patella, and those with objective patellar instability. We evaluated the clinical results in 30 patients in each group. The outcome was documented at 3, 12 and 24 months using the Lysholm scale, the Kujala score, and a visual analogue pain score. Post-operatively, all but one patient in the instability group who had a patellar dislocation requiring further surgery reported good improvement with no further subluxation or dislocation. All patients in both groups had a marked improvement in pain and functional score. Two patients sustained a tibial fracture six and seven weeks after surgery. One patient suffered a per-operative fracture of the tibial tubercle which later required further fixation. If carefully performed, this type of transfer of the tibial tubercle appears to be a satisfactory technique for the treatment of patients with an increased tibial tubercle-trochlear groove distance and who present with symptoms related to lateral maltracking of the patella

Patients with skeletal dysplasia are prone to developing advanced osteoarthritis of the knee requiring total knee replacement (TKR) at a younger age than the general population. TKR in this unique group of patients is a technically demanding procedure owing to the deformity, flexion contracture, generalised hypotonia and ligamentous laxity. We retrospectively reviewed the outcome of 11 TKRs performed in eight patients with skeletal dysplasia at our institution using the Stanmore Modular Individualised Lower Extremity System (SMILES) custom-made rotating-hinge TKR. There were three men and five women with mean age of 57 years (41 to 79). Patients were followed clinically and radiologically for a mean of seven years (3 to 11.5). The mean Knee Society clinical and function scores improved from 24 (14 to 36) and 20 (5 to 40) pre-operatively, respectively, to 68 (28 to 80) and 50 (22 to 74), respectively, at final follow-up. Four complications were recorded, including a patellar fracture following a fall, a tibial peri-prosthetic fracture, persistent anterior knee pain, and aseptic loosening of a femoral component requiring revision. Our results demonstrate that custom primary rotating-hinge TKR in patients with skeletal dysplasia is effective at relieving pain, with a satisfactory range of movement and improved function. It compensates for bony deformity and ligament deficiency and reduces the likelihood of corrective osteotomy. Patellofemoral joint complications are frequent and functional outcome is worse than with primary TKR in the general population

Anterior cruciate ligament (ACL) graft failure from rupture, attenuation, or malposition may cause recurrent subjective instability and objective laxity, and occurs in 3% to 22% of ACL reconstruction (ACLr) procedures. Revision ACLr is often indicated to restore knee stability, improve knee function, and facilitate return to cutting and pivoting activities. Prior to reconstruction, a thorough clinical and diagnostic evaluation is required to identify factors that may have predisposed an individual to recurrent ACL injury, appreciate concurrent intra-articular pathology, and select the optimal graft for revision reconstruction. Single-stage revision can be successful, although a staged approach may be used when optimal tunnel placement is not possible due to the position and/or widening of previous tunnels. Revision ACLr often involves concomitant procedures such as meniscal/chondral treatment, lateral extra-articular augmentation, and/or osteotomy. Although revision ACLr reliably restores knee stability and function, clinical outcomes and reoperation rates are worse than for primary ACLr.

Cite this article: Bone Joint J 2023;105-B(5):474–480.

Advanced 3D imaging and CT-based navigation have emerged as valuable tools to use in total knee arthroplasty (TKA), for both preoperative planning and the intraoperative execution of different philosophies of alignment. Preoperative planning using CT-based 3D imaging enables more accurate prediction of the size of components, enhancing surgical workflow and optimizing the precision of the positioning of components. Surgeons can assess alignment, osteophytes, and arthritic changes better. These scans provide improved insights into the patellofemoral joint and facilitate tibial sizing and the evaluation of implant-bone contact area in cementless TKA. Preoperative CT imaging is also required for the development of patient-specific instrumentation cutting guides, aiming to reduce intraoperative blood loss and improve the surgical technique in complex cases. Intraoperative CT-based navigation and haptic guidance facilitates precise execution of the preoperative plan, aiming for optimal positioning of the components and accurate alignment, as determined by the surgeon’s philosophy. It also helps reduce iatrogenic injury to the periarticular soft-tissue structures with subsequent reduction in the local and systemic inflammatory response, enhancing early outcomes. Despite the increased costs and radiation exposure associated with CT-based navigation, these many benefits have facilitated the adoption of imaged based robotic surgery into routine practice. Further research on ultra-low-dose CT scans and exploration of the possible translation of the use of 3D imaging into improved clinical outcomes are required to justify its broader implementation.

Cite this article: Bone Joint J 2024;106-B(9):892–897.

Aims

The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process.

Aims

This study aimed to evaluate if total knee arthroplasty (TKA) femoral components aligned in either mechanical alignment (MA) or kinematic alignment (KA) are more biomimetic concerning trochlear sulcus orientation and restoration of trochlear height.

Aims

The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population.

A retrospective review of 50 knees in 46 patients treated by arthroscopic removal of chondral flaps is reported. There was a relationship between the site of the flap and the type of symptoms; patellofemoral flaps produced anterior knee pain, posterior condylar flaps produced instability. At review after 18 to 36 months, after a second arthroscopy in eight cases, 44 of the 50 knees had retained significant improvement and 33 were symptom-free

We reviewed 74 partial medial meniscectomies in 57 patients with stable knees, to assess the long-term functional and radiological outcome. The International Knee Documentation Committee score and the residual laxity were assessed in both knees. At the time of surgery the mean age of the patients was 36 ± 11 years and the mean follow-up was 12 ± 1 years. All had a limited medial meniscectomy. The anterior cruciate ligament was intact in all cases. The meniscal tear was vertical in 95% and complex in 5%. The posterior part of the meniscus was removed in 99%. A peripheral rim was preserved in all cases. After 12 years 95% of the patients were satisfied or very satisfied with their knee(s). Objectively, 57% had grade A function and 43% were grade B. The outcome correlated only with the presence of anterior knee pain at final follow-up. In the 49 cases of arthroscopic meniscectomy for which there was a contralateral normal knee there was narrowing of the ‘joint-space’ in 16% of the operated knees. There was no correlation between this and other parameters such as age or different meniscal pathologies

Patellofemoral problems are a common cause of morbidity and reoperation after total knee arthroplasty. We made a prospective study of 52 patients who had bilateral arthroplasty (104 knees) and in whom the patella was resurfaced on one side and not on the other. A movable-bearing prosthesis with an anatomical femoral groove was implanted on both sides by the same surgeon using an otherwise identical technique. The mean follow-up was 5.24 years (2 to 10). In the 30 available patients (60 knees) there was no difference between the two sides in subjective preference, performance on ascending and descending stairs or the incidence of anterior knee pain. Radiographs showed no differences in prosthetic alignment, femoral condylar height, patellar congruency or joint line position. The use of an appropriate prosthetic design and careful surgical technique can provide equivalent results after knee arthroplasty with or without patellar resurfacing. Given the indications and criteria, which we discuss, retention of the patellar surface is an acceptable option

Anterior knee pain due to dysplasia of the extensor mechanism is common. We have studied 137 knees (103 patients) in order to identify a rapid and reproducible radiological feature which would indicate the need for further analysis. Overall, 67 knees (49%) had at least one radiological abnormality; 70 (51%) were considered normal. There were five cases of Dejour type-3 dysplasia of the femoral trochlea, nine of type-2 and 12 of type-1. There were 49 cases of patella alta and five of patella infera. Four knees had an abnormal lateral patellofemoral angle (patellar tilt), and in 15 knees there was more than one abnormality. Classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of the lateral patellofemoral angle. Patellar height was more easily measured but took time. The sulcus angle is an easily and rapidly measurable feature which was reproducible and was closely related to other features of dysplasia of the extensor mechanism. The finding of a normal sulcus angle suggested that seeking other radiological evidence of malalignment of the extensor mechanism was unlikely to reveal additional useful information. The severity of other features of dysplasia of the extensor mechanism correlated with increasing sulcus angle

We reviewed the outcome of 146 Insall-Burstein II total knee replacements carried out in 121 patients over a period of nearly four years in a general orthopaedic unit. At a mean follow-up of ten years, 94 knees in 78 patients were available for review. Six patients (7 knees) were lost to follow-up and 37 (45 knees) had died. The clinical outcome using the scoring system of the Hospital for Special Surgery (HSS) was excellent or good in 79% of patients, fair in 14% and poor in 7%. The mean preoperative HSS score was 31, improving to 79 at the latest review. Using the newer rating system of the Knee Society, the mean score at ten years was 87 and the mean functional score 56. The arc of flexion improved from a mean preoperative value of 88° to 100°. The 18 patients who had had a previous high tibial osteotomy were analysed separately and were found to have benefited equally from the operation. Nine prostheses were revised, giving a cumulative survival rate of 92.3% at ten years. Radiological evaluation of 104 radiographs showed radiolucent lines around ten tibial components, none of which required revision. Anterior knee pain was a significant problem

Nine patients underwent arthrodesis of the knee using a customised coupled nail (the Mayday arthrodesis nail), five after infected arthroplasty, one following failed arthrodesis, one for intractable anterior knee pain, one for Charcot instability and one after trauma. Comparison was made with 17 arthrodeses, eight undertaken using external fixation, four with dual compression plates, and five with long Küntscher nails. Union was achieved in all patients (100%) at a mean time of ten months using the customised implant. There were no complications despite early weight-bearing. No further procedures were required. This contrasted with a rate of union of 53% and a complication rate of 76% with alternative techniques. Of this second group, 76% required a further operative procedure. We compared the Mayday arthrodesis nail with other techniques of arthrodesis of the knee. The differences in the need for further surgery and occurrence of complications were statistically significant (p < 0.001), and differences in the rate of nonunion and inpatient stay of less than three weeks were also significant (p < 0.05) using Fisher’s exact test. We conclude that a customised coupled intramedullary nail can give excellent stability allowing early weight-bearing, and results in a high rate of union with minimal postoperative complications

Aims

The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery.

Aims

Access to total knee arthroplasty (TKA) is sometimes restricted for patients with severe obesity (BMI ≥ 40 kg/m²). This study compares the cost per quality-adjusted life year (QALY) associated with TKA in patients with a BMI above and below 40 kg/m² to examine whether this is supported.

Aims

To determine the value of scoliosis surgery, it is necessary to evaluate outcomes in domains that matter to patients. Since randomized trials on adolescent idiopathic scoliosis (AIS) are scarce, prospective cohort studies with comparable outcome measures are important. To enhance comparison, a core set of patient-related outcome measures is available. The aim of this study was to evaluate the outcomes of AIS fusion surgery at two-year follow-up using the core outcomes set.

Aims

Debate remains whether the patella should be resurfaced during total knee replacement (TKR). For non-resurfaced TKRs, we estimated what the revision rate would have been if the patella had been resurfaced, and examined the risk of re-revision following secondary patellar resurfacing.

Aims

To compare changes in gait kinematics and walking speed 24 months after conventional (C-MLS) and minimally invasive (MI-MLS) multilevel surgery for children with diplegic cerebral palsy (CP).

Aims

To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period.

Aims

For many designs of total knee arthroplasty (TKA) it remains unclear whether cemented or uncemented fixation provides optimal long-term survival. The main limitation in most studies is a retrospective or non-comparative study design. The same is true for comparative trials looking only at the survival rate as extensive sample sizes are needed to detect true differences in fixation and durability. Studies using radiostereometric analysis (RSA) techniques have shown to be highly predictive in detecting late occurring aseptic loosening at an early stage. To investigate the difference in predicted long-term survival between cemented, uncemented, and hybrid fixation of TKA, we performed a randomized controlled trial using RSA.

Aims

This study aimed to evaluate the association between the sagittal alignment of the femoral component in total knee arthroplasty (TKA) and new Knee Society Score (2011KSS), under the hypothesis that outliers such as the excessive extended or flexed femoral component were related to worse clinical outcomes.

Aims

The prevalence of combined abnormalities of femoral torsion (FT) and tibial torsion (TT) is unknown in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aimed to determine the prevalence of combined abnormalities of FT and TT, and which subgroups are associated with combined abnormalities of FT and TT.

Aims

A pragmatic, single-centre, double-blind randomized clinical trial was conducted in a NHS teaching hospital to evaluate whether there is a difference in functional knee scores, quality-of-life outcome assessments, and complications at one-year after intervention between total knee arthroplasty (TKA) and patellofemoral arthroplasty (PFA) in patients with severe isolated patellofemoral arthritis.