Aims. This study aims to investigate the effects of posterior tibial slope (PTS) on knee kinematics involved in the post-cam mechanism in bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) using computer simulation. Methods. In total, 11 different PTS (0° to 10°) values were simulated to evaluate the effect of PTS on anterior post-cam contact conditions and knee kinematics in BCS TKA during weight-bearing stair climbing (from 86° to 6° of knee flexion). Knee kinematics were expressed as the lowest points of the medial and lateral femoral condyles on the surface of the tibial insert, and the anteroposterior translation of the femoral component relative to the tibial insert. Results. Anterior post-cam contact in BCS TKA was observed with the knee near full extension if PTS was 6° or more. BCS TKA showed a bicondylar roll forward movement from 86° to mid-flexion, and two different patterns from mid-flexion to knee extension: screw home movement without anterior post-cam contact and bicondylar roll forward movement after anterior post-cam contact. Knee kinematics in the simulation showed similar trends to the clinical in vivo data and were almost within the range of inter-specimen variability. Conclusion. Postoperative knee kinematics in BCS TKA differed according to PTS and anterior post-cam contact; in particular, anterior post-cam contact changed knee kinematics, which may affect the patient’s perception of the knee during activities. Cite this article: Bone Joint Res 2020;9(11):761–767

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

The clinical diagnosis of a partial tear of the anterior cruciate ligament (ACL) is still subject to debate. Little is known about the contribution of each ACL bundle during the Lachman test. We investigated this using six fresh-frozen cadaveric lower limbs. Screws were placed in the femora and tibiae as fixed landmarks for digitisation of the bone positions. The femur was secured horizontally in a clamp. A metal hook was screwed to the tibial tubercle and used to apply a load of 150 N directed anteroposteriorly to the tibia to simulate the Lachman test. The knees then received constant axial compression and 3D knee kinematic data were collected by digitising the screw head positions in 30° flexion under each test condition. Measurements of tibial translation and rotation were made, first with the ACL intact, then after sequential cutting of the ACL bundles, and finally after complete division of the ACL. Two-way analysis of variance analysis was performed. During the Lachman test, in all knees and in all test conditions, lateral tibial translation exceeded that on the medial side. With an intact ACL, both anterior and lateral tibial landmarks translated significantly more than those on the medial side (p < 0.001). With sequential division of the ACL bundles, selective cutting of the posterolateral bundle (PLB) did not increase translation of any landmark compared with when the ACL remained intact. Cutting the anteromedial bundle (AMB) resulted in an increased anterior translation of all landmarks. Compared to the intact ACL, when the ACL was fully transected a significant increase in anterior translation of all landmarks occurred (p < 0.001). However, anterior tibial translation was almost identical after AMB or complete ACL division. We found that the AMB confers its most significant contribution to tibial translation during the Lachman test, whereas the PLB has a negligible effect on anterior translation. Section of the PLB had a greater effect on increasing the internal rotation of the tibia than the AMB. However, its contribution of a mean of 2.8° amplitude remains low. The clinical relevance of our investigation suggests that, based on anterior tibial translation only, one cannot distinguish between a full ACL and an isolated AMB tear. Isolated PLB tears cannot be detected solely by the Lachman test, as this bundle probably contributes more resistance to the pivot shift

Aims

The aim of this study was to screen the entire genome for genetic markers associated with risk for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injury.

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

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

Mechanical failure because of wear or fracture of the polyethylene tibial post in posteriorly-stabilised total knee replacements has been extensively described. In this study of 12 patients with a clinically and radiologically successful NexGen LPS posteriorly-stabilised prosthesis impingement of the anterior tibial post was evaluated in vivo in three dimensions during gait using radiologically-based image-matching techniques. Impingement was observed in all images of the patients during the stance phase, although the NexGen LPS was designed to accommodate 14° of hyperextension of the component before impingement occurred. Impingement arises as a result of posterior translation of the femur during the stance phase. Further attention must therefore be given to the configuration of the anterior portion of the femoral component and the polyethylene post when designing posteriorly-stabilised total knee replacements

Objectives. To assess the effectiveness of a modified tibial tubercle osteotomy as a treatment for arthroscopically diagnosed chondromalacia patellae. Methods. A total of 47 consecutive patients (51 knees) with arthroscopically proven chondromalacia, who had failed conservative management, underwent a modified Fulkerson tibial tubercle osteotomy. The mean age was 34.4 years (19.6 to 52.2). Pre-operatively, none of the patients exhibited signs of patellar maltracking or instability in association with their anterior knee pain. The minimum follow-up for the study was five years (mean 72.6 months (62 to 118)), with only one patient lost to follow-up. Results. A total of 50 knees were reviewed. At final follow-up, the Kujala knee score improved from 39.2 (12 to 63) pre-operatively to 57.7 (16 to 89) post-operatively (p < 0.001). The visual analogue pain score improved from 7.8 (4 to 10) pre-operatively to 5.0 (0 to 10) post-operatively. Overall patient satisfaction with good or excellent results was 72%. Patients with the lowest pre-operative Kujala score benefitted the most. Older patients benefited less than younger ones. The outcome was independent of the grade of chondromalacia. Six patients required screw removal. There were no major complications. Conclusions. We conclude that this modification of the Fulkerson procedure is a safe and useful operation to treat anterior knee pain in well aligned patellofemoral joints due to chondromalacia patellae in adults, when conservative measures have failed

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

The biomechanical function of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) remains controversial. Some studies report that the AM bundle stabilises the knee joint in anteroposterior (AP) translation and rotational movement (both internal and external) to the same extent as the PL bundle. Others conclude that the PL bundle is more important than the AM in controlling rotational movement. The objective of this randomised cohort study involving 60 patients (39 men and 21 women) with a mean age of 32.9 years (18 to 53) was to evaluate the function of the AM and the PL bundles of the ACL in both AP and rotational movements of the knee joint after single-bundle and double-bundle ACL reconstruction using a computer navigation system. In the double-bundle group the patients were also randomised to have the AM or the PL bundle tensioned first, with knee laxity measured after each stage of reconstruction. All patients had isolated complete ACL tears, and the presence of a meniscal injury was the only supplementary pathology permitted for inclusion in the trial. The KT-1000 arthrometer was used to apply a constant load to evaluate the AP translation and the rolimeter was used to apply a constant rotational force. For the single-bundle group deviation was measured before and after ACL reconstruction. In the double-bundle group deviation was measured for the ACL-deficient, AM- or PL-reconstructed first conditions and for the total reconstruction. We found that the AM bundle in the double-bundle group controlled rotation as much as the single-bundle technique, and to a greater extent than the PL bundle in the double-bundle technique. The double-bundle technique increases AP translation and rotational stability in internal rotation more than the single-bundle technique

Anterior cruciate ligament (ACL) reconstruction is commonly performed and has been for many years. Despite this, the technical details related to ACL anatomy, such as tunnel placement, are still a topic for debate. In this paper, we introduce the flat ribbon concept of the anatomy of the ACL, and its relevance to clinical practice.

Cite this article: Bone Joint J 2016;98-B:1020–6.

We examined the association of graft type with the risk of early revision of primary anterior cruciate ligament reconstruction (ACLR) in a community-based sample. A retrospective analysis of a cohort of 9817 ACLRs recorded in an ACLR Registry was performed. Patients were included if they underwent primary ACLR with bone–patellar tendon–bone autograft, hamstring tendon autograft or allograft tissue. Aseptic failure was the main endpoint of the study. After adjusting for age, gender, ethnicity, and body mass index, allografts had a 3.02 times (95% confidence interval (CI) 1.93 to 4.72) higher risk of aseptic revision than bone–patellar tendon–bone autografts (p < 0.001). Hamstring tendon autografts had a 1.82 times (95% CI 1.10 to 3.00) higher risk of revision compared with bone–patellar tendon–bone autografts (p = 0.019). For each year increase in age, the risk of revision decreased by 7% (95% CI 5 to 9). In gender-specific analyses a 2.26 times (95% CI 1.15 to 4.44) increased risk of hamstring tendon autograft revision in females was observed compared with bone–patellar tendon–bone autograft. We conclude that allograft tissue, hamstring tendon autografts, and younger age may all increase the risk of early revision surgery after ACLR.

Cite this article: Bone Joint J 2013;95-B:623–8.

Aims

To examine the rates of hamstring graft salvage with arthroscopic debridement of infected anterior cruciate ligament (ACL) reconstruction as reported in the literature and discuss functional outcomes.

Aims

The aim of this study was to investigate the long-term clinical and radiological outcome of patients who suffer recurrent injuries to the anterior cruciate ligament (ACL) after reconstruction and require revision surgery.

Loss of proprioception following an anterior cruciate ligament (ACL) injury has been well documented. We evaluated proprioception in both the injured and the uninjured limb in 25 patients with ACL injury and in 25 healthy controls, as assessed by joint position sense (JPS), the threshold for the detection of passive movement (TDPM) and postural sway during single-limb stance on a force plate. There were significant proprioceptive deficits in both ACL-deficient and uninjured knees compared with control knees, as assessed by the angle reproduction test (on JPS) and postural sway on single limb stance. The degree of loss of proprioception in the ACL-deficient knee and the unaffected contralateral knee joint in the same patient was similar. The TDPM in the injured knee was significantly higher than that of controls at 30° and 70° of flexion. The TDPM of the contralateral knee joint was not significantly different from that in controls.

Based on these findings, the effect of proprioceptive training of the contralateral uninjured knee should be explored.

Cite this article: Bone Joint J 2013;95-B:188–91.

We investigated the role of a functional brace worn for four months in the treatment of patients with an acute isolated tear of the posterior cruciate ligament to determine whether reduction of the posterior tibial translation during the healing period would give an improved final position of the tibia. The initial and follow-up stability was tested by Rolimeter arthrometry and radiography. The clinical outcome was evaluated using the Lysholm score, the Tegner score and the International Knee Documentation Committee scoring system at follow-up at one and two years. In all, 21 patients were studied, 21 of whom had completed one-year and 17 a two-year follow-up.

The initial mean posterior sag (Rolimeter measurement) of 7.1 mm (5 to 10) was significantly reduced after 12 months to a mean of 2.3 mm (0 to 6, p < 0.001) and to a mean of 3.2 mm (2 to 7, p = 0.001) after 24 months. Radiological measurement gave similar results. The mean pre-injury Lysholm score was normal at 98 (95 to 100). At follow-up, a slight decrease in the mean values was observed to 94.0 (79 to 100, p = 0.001) at one year and 94.0 (88 to 100, p = 0.027, at two years).

We concluded that the posterior cruciate ligament has an intrinsic healing capacity and, if the posteriorly translated tibia is reduced to a physiological position, it can heal with less attentuation. The applied treatment produces a good to excellent functional result.

We investigated whether strontium-enriched calcium phosphate cement (Sr-CPC)-treated soft-tissue tendon graft results in accelerated healing within the bone tunnel in reconstruction of the anterior cruciate ligament (ACL). A total of 30 single-bundle ACL reconstructions using tendo Achillis allograft were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, whereas that on the contralateral limb was untreated and served as a control. At timepoints three, six, nine, 12 and 24 weeks after surgery, three animals were killed for histological examination. At six weeks, the graft–bone interface in the control group was filled in with fibrovascular tissue. However, the gap in the Sr-CPC group had already been completely filled in with new bone, and there was evidence of the early formation of Sharpey fibres. At 24 weeks, remodelling into a normal ACL–bone-like insertion was found in the Sr-CPC group. Coating of Sr-CPC on soft tissue tendon allograft leads to accelerated graft healing within the bone tunnel in a rabbit model of ACL reconstruction using Achilles tendon allograft.

Cite this article: Bone Joint J 2013;95-B:923–8.

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

Aims. Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model. Methods. We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition. Results. Mid-level inserts reduced varus angulations compared to PS inserts by a median of 0.4°, 0.9°, and 1.5° at 0°, 30°, and 90° of flexion, respectively, and reduced valgus angulations by a median of 0.3°, 1.0°, and 1.2° (p ≤ 0.027 for all comparisons). Mid-level inserts reduced net IE rotations by a median of 5.6°, 14.7°, and 17.5° at 0°, 30°, and 90°, respectively (p = 0.012). Mid-level inserts reduced anterior tibial translation only at 90° of flexion by a median of 3.0 millimetres (p = 0.036). With an applied varus moment, the mid-level insert decreased LCL force compared to the PS insert at all three flexion angles that were tested (p ≤ 0.036). In contrast, with a valgus moment the mid-level insert did not reduce MCL force. With an applied internal rotation moment, the mid-level insert decreased LCL force at 30° and 90° by a median of 25.7 N and 31.7 N, respectively (p = 0.017 and p = 0.012). With an external rotation moment, the mid-level insert decreased MCL force at 30° and 90° by a median of 45.7 N and 20.0 N, respectively (p ≤ 0.017 for all comparisons). With an applied anterior load, MCL and LCL forces showed no differences between the two inserts at 30° and 90° of flexion. Conclusion. The mid-level insert used in this study decreased coronal and axial plane laxities compared to the PS insert, but its stabilizing benefit in the sagittal plane was limited. Both mid-level and PS inserts depended on the MCL to resist anterior loads during a simulated clinical exam of anterior laxity. Cite this article: Bone Jt Open 2023;4(6):432–441

Aims. The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA). Methods. Two experimentally validated finite element models of tibia were implanted with UKA-M, Bi-UKA, and BCR-TKA. Intraoperative loads were applied through the condyles, anterior cruciate ligament (ACL), medial collateral ligament (MCL), and lateral collateral ligament (LCL), and the risk of fracture (ROF) was evaluated in the spine as the ratio of the 95. th. percentile maximum principal elastic strains over the tensile yield strain of proximal tibial bone. Results. Peak tensile strains occurred on the anterior portion of the medial sagittal cut in all simulations. Lateral translation of the medial implant in Bi-UKA had the largest increase in ROF of any of the implant positions (43%). Overstuffing the joint by 2 mm had a much larger effect, resulting in a six-fold increase in ROF. Bi-UKA had ~10% increased ROF compared to UKA-M for both the male and female models, although the smaller, less dense female model had a 1.4 times greater ROF compared to the male model. Removal of anterior bone akin to BCR-TKA doubled ROF compared to Bi-UKA. Conclusion. Tibial eminence avulsion fracture has a similar risk associated with Bi-UKA to UKA-M. The risk is higher for smaller and less dense tibiae. To minimize risk, it is most important to avoid overstuffing the joint, followed by correctly positioning the medial implant, taking care not to narrow the bone island anteriorly. Cite this article: Bone Joint Res 2022;11(8):575–584

Aims. A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes. Methods. ACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions. Results. Anterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs. Conclusion. Fixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon. Cite this article: Bone Joint Res 2022;11(7):494–502

Aims. The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthroplasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinematics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA). Methods. A total of 40 patients with end-stage osteoarthritis were included in this randomized controlled trial. All patients performed a step-up and lunge task in front of a monoplane fluoroscope one year postoperatively. Femorotibial contact point (CP) locations were determined at every flexion angle and compared between the groups. RSA images were taken at baseline, six weeks, three, six, 12, and 24 months postoperatively. Clinical and functional outcomes were compared postoperatively for two years. Results. The BCR-TKA demonstrated a kinematic pattern comparable to the natural knee’s screw-home mechanism in the step-up task. In the lunge task, the medial CP of the BCR-TKA was more anterior in the early flexion phase, while laterally the CP was more posterior during the entire movement cycle. The BCR-TKA group showed higher tibial migration. No differences were found for the clinical and functional outcomes. Conclusion. The BCR-TKA shows a different kinematic pattern in early flexion/late extension compared to the CR-TKA. The difference between both implants is mostly visible in the flexion phase in which the anterior cruciate ligament is effective; however, both designs fail to fully replicate the motion of a natural knee. The higher migration of the BCR-TKA was concerning and highlights the importance of longer follow-up. Cite this article: Bone Joint J 2023;105-B(1):35–46

Aims. As has been shown in larger animal models, knee immobilization can lead to arthrofibrotic phenotypes. Our study included 168 C57BL/6J female mice, with 24 serving as controls, and 144 undergoing a knee procedure to induce a contracture without osteoarthritis (OA). Methods. Experimental knees were immobilized for either four weeks (72 mice) or eight weeks (72 mice), followed by a remobilization period of zero weeks (24 mice), two weeks (24 mice), or four weeks (24 mice) after suture removal. Half of the experimental knees also received an intra-articular injury. Biomechanical data were collected to measure passive extension angle (PEA). Histological data measuring area and thickness of posterior and anterior knee capsules were collected from knee sections. Results. Experimental knees immobilized for four weeks demonstrated mean PEAs of 141°, 72°, and 79° after zero, two, and four weeks of remobilization (n = 6 per group), respectively. Experimental knees demonstrated reduced PEAs after two weeks (p < 0.001) and four weeks (p < 0.0001) of remobilization compared to controls. Following eight weeks of immobilization, experimental knees exhibited mean PEAs of 82°, 73°, and 72° after zero, two, and four weeks of remobilization, respectively. Histological analysis demonstrated no cartilage degeneration. Similar trends in biomechanical and histological properties were observed when intra-articular violation was introduced. Conclusion. This study established a novel mouse model of robust knee contracture without evidence of OA. This was appreciated consistently after eight weeks of immobilization and was irrespective of length of remobilization. As such, this arthrofibrotic model provides opportunities to investigate molecular pathways and therapeutic strategies. Cite this article: Bone Joint Res 2023;12(1):58–71

Aims. Unicompartmental knee arthroplasty (UKA) is the preferred treatment for anterior medial knee osteoarthritis (OA) owing to the rapid postoperative recovery. However, the risk factors for UKA failure remain controversial. Methods. The clinical data of Oxford mobile-bearing UKAs performed between 2011 and 2017 with a minimum follow-up of five years were retrospectively analyzed. Demographic, surgical, and follow-up data were collected. The Cox proportional hazards model was used to identify the risk factors that contribute to UKA failure. Kaplan-Meier survival was used to compare the effect of the prosthesis position on UKA survival. Results. A total of 407 patients who underwent UKA were included in the study. The mean age of patients was 61.8 years, and the mean follow-up period of the patients was 91.7 months. The mean Knee Society Score (KSS) preoperatively and at the last follow-up were 64.2 and 89.7, respectively (p = 0.001). Overall, 28 patients (6.9%) with UKA underwent revision due to prosthesis loosening (16 patients), dislocation (eight patients), and persistent pain (four patients). Cox proportional hazards model analysis identified malposition of the prostheses as a high-risk factor for UKA failure (p = 0.007). Kaplan-Meier analysis revealed that the five-year survival rate of the group with malposition was 85.1%, which was significantly lower than that of the group with normal position (96.2%; p < 0.001). Conclusion. UKA constitutes an effective method for treating anteromedial knee OA, with an excellent five-year survival rate. Aseptic loosening caused by prosthesis malposition was identified as the main cause of UKA failure. Surgeons should pay close attention to prevent the potential occurrence of this problem. Cite this article: Bone Jt Open 2023;4(12):914–922

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. Methods. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics. Results. There were evident biomechanical differences between the simulated patient models, but also trends that appeared reproducible at the population level. Optimizing the implant position significantly reduced the maximum observed strain root mean square deviations within the cohort from 36.5% to below 5.3% for all but the anterolateral ligament; and concomitantly reduced the kinematic deviations from 3.8 mm (SD 1.7) and 4.7° (SD 1.9°) with MA to 2.7 mm (SD 1.4) and 3.7° (SD 1.9°) relative to the pre-diseased state. To achieve this, the femoral component consistently required translational adjustments in the anterior, lateral, and proximal directions, while the tibial component required a more posterior slope and varus rotation in most cases. Conclusion. These findings confirm that MA-induced biomechanical alterations relative to the pre-diseased state can be reduced by optimizing the implant position, and may have implications to further advance pre-planning in robotic-assisted surgery in order to restore pre-diseased knee function. Cite this article: Bone Joint J 2024;106-B(11):1231–1239

Aims. A fracture of the medial tibial plateau is a serious complication of Oxford mobile-bearing unicompartmental knee arthroplasty (OUKA). The risk of these fractures is reportedly lower when using components with a longer keel-cortex distance (KCDs). The aim of this study was to examine how slight varus placement of the tibial component might affect the KCDs, and the rate of tibial plateau fracture, in a clinical setting. Methods. This retrospective study included 255 patients who underwent 305 OUKAs with cementless tibial components. There were 52 males and 203 females. Their mean age was 73.1 years (47 to 91), and the mean follow-up was 1.9 years (1.0 to 2.0). In 217 knees in 187 patients in the conventional group, tibial cuts were made orthogonally to the tibial axis. The varus group included 88 knees in 68 patients, and tibial cuts were made slightly varus using a new osteotomy guide. Anterior and posterior KCDs and the origins of fracture lines were assessed using 3D CT scans one week postoperatively. The KCDs and rate of fracture were compared between the two groups. Results. Medial tibial fractures occurred after surgery in 15 patients (15 OUKAs) in the conventional group, but only one patient (one OUKA) had a tibial fracture after surgery in the varus group. This difference was significant (6.9% vs 1.1%; p = 0.029). The mean posterior KCD was significantly shorter in the conventional group (5.0 mm (SD 1.7)) than in the varus group (6.1 mm (SD 2.1); p = 0.002). Conclusion. In OUKA, the distance between the keel and posterior tibial cortex was longer in our patients with slight varus alignment of the tibial component, which seems to decrease the risk of postoperative tibial fracture. Cite this article: Bone Joint J 2022;104-B(10):1118–1125

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

Aims. Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters. Methods. An upright, open MRI was used to directly measure tibiofemoral contact area, centroid location, and alignment in 18 individuals with unilateral ACL rupture within the last five years. Eight participants had been treated nonoperatively and ten had ACL reconstruction performed within one year of injury. All participants were high-functioning and had returned to sport or recreational activities. Healthy contralateral knees served as controls. Participants were imaged in a standing posture with knees fully extended. Results. Participants’ mean age was 28.4 years (SD 7.3), the mean time since injury was 2.7 years (SD 1.6), and the mean International Knee Documentation Subjective Knee Form score was 84.4 (SD 13.5). ACL injury was associated with a 10% increase (p = 0.001) in contact area, controlling for compartment, sex, posture, age, body mass, and time since injury. ACL injury was associated with a 5.2% more posteriorly translated medial centroid (p = 0.001), equivalent to a 2.6 mm posterior translation on a representative tibia with mean posteroanterior width of 49.4 mm. Relative to the femur, the tibiae of ACL ruptured knees were 2.3 mm more anteriorly translated (p = 0.003) and 2.6° less externally rotated (p = 0.010) than healthy controls. ACL reconstruction was not associated with an improvement in any measure. Conclusion. ACL rupture was associated with an increased contact area, posteriorly translated medial centroid, anterior tibial translation, and reduced tibial external rotation in full extension. These changes were present 2.7 years post-injury regardless of ACL reconstruction status. Cite this article: Bone Joint J 2021;103-B(9):1505–1513

Aims. MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation. Methods. A consecutive cohort of 149 patients who had undergone semitendinosus autograft ACL reconstruction, using femoral and tibial adjustable loop fixations, were evaluated retrospectively postoperatively at two years. All underwent MRI analysis of the ACL graft, performed using signal-to-noise quotient (SNQ) and the Howell score. Functional outcome scores (Lysholm, Tegner, International Knee Documentation Committee (IKDC) subjective, and IKDC objective) were obtained and all patients underwent instrumented side-to-side anterior laxity differential laxity testing. Results. Two-year postoperative mean outcome scores were: Tegner 6.5 (2 to 10); Lysholm 89.8 (SD 10.4; 52 to 100); and IKDC subjective 86.8 (SD 11.8; 51 to 100). The objective IKDC score was 86% A (128 patients), 13% B (19 patients), and 1% C (two patients). Mean side-to-side anterior laxity difference (134 N force) was 0.6 mm (SD 1.8; -4.1 to 5.6). Mean graft SNQ was 2.0 (SD 3.5; -14 to 17). Graft Howell scores were I (61%, 91 patients), II (25%, 37 patients), III (13%, 19 patients), and IV (1%, two patients). There was no correlation between either Howell score or SNQ with instrumented anterior or Lysholm, Tegner, and IKDC scores, nor was any correlation found between patient age and ACL graft SNQ or Howell score. Conclusion. The two-year postoperative MRI appearances of four-strand, semitendinosus ACL autografts (as measured by SNQ and Howell score) do not appear to have a relationship with postoperative functional scores, instrumented anterior laxity, or patient age at surgery. Other tools for analysis of graft maturity should be developed. Cite this article: Bone Jt Open 2021;2(8):569–575

Aims. Medial pivot (MP) total knee arthroplasties (TKAs) were designed to mimic native knee kinematics with their deep medial congruent fitting of the tibia to the femur almost like a ball-on-socket, and a flat lateral part. GMK Sphere is a novel MP implant. Our primary aim was to study the migration pattern of the tibial tray of this TKA. Methods. A total of 31 patients were recruited to this single-group radiostereometric analysis (RSA) study and received a medial pivot GMK Sphere TKA. The distributions of male patients versus female patients and right versus left knees were 21:10 and 17:14, respectively. Mean BMI was 29 kg/m. 2. (95% confidence interval (CI) 27 to 30) and mean age at surgery was 63 years (95% CI 61 to 66). Maximum total point motions (MTPMs), medial, proximal, and anterior translations and transversal, internal, and varus rotations were calculated at three, 12, and 24 months. Patient-reported outcome measure data were also retrieved. Results. MTPMs at three, 12, and 24 months were 1.0 mm (95% CI 0.8 to 1.2), 1.3 mm (95% CI 0.9 to 1.7), and 1.4 mm (0.8 to 2.0), respectively. The Forgotten Joint Score was 79 (95% CI 39 to 95) and Knee Injury and Osteoarthritis Outcome Score obtained at two years was 94 (95% CI 81 to 100), 86 (95% CI 75 to 93), 94 (95% CI 88 to 100), 69 (95% CI 48 to 88), and 81 (95% CI59 to 100) for Pain, Symptoms, Activities of Daily Living, Sport & Recreation, and Quality of Life, respectively. Conclusion. In conclusion, we found that the mean increase in MTPM was lower than 0.2 mm between 12 and 24 months and thus apparently stable. Yet the GMK Sphere had higher migration at one and two years than anticipated. Based on current RSA data, we therefore cannot conclude on the long-term performance of the implant, pending further assessment. Cite this article: Bone Jt Open 2021;2(9):737–744

Aims. Tourniquets have potential adverse effects including postoperative thigh pain, likely caused by their ischaemic and possible compressive effects. The aims of this preliminary study were to determine if it is possible to directly measure intramuscular pH in human subjects over time, and to measure the intramuscular pH changes resulting from tourniquet ischaemia in patients undergoing knee arthroscopy. Methods. For patients undergoing short knee arthroscopic procedures, a sterile calibrated pH probe was inserted into the anterior fascial compartment of the leg after skin preparation, but before tourniquet inflation. The limb was elevated for three minutes prior to tourniquet inflation to 250 mmHg or 300 mmHg. Intramuscular pH was recorded at one-second intervals throughout the procedure and for 20 minutes following tourniquet deflation. Probe-related adverse events were recorded. Results. A total of 27 patients were recruited to the study. Mean tourniquet time was 21 minutes (10 to 56). Tourniquet pressure was 300 mmHg for 21 patients and 250 mmHg for six patients. Mean muscle pH prior to tourniquet inflation was 6.80. Muscle pH decreased upon tourniquet inflation, with a steeper fall in the first ten minutes than for the rest of the procedure. Change in muscle pH was significant after five minutes of tourniquet ischaemia (p < 0.001). Mean muscle pH prior to tourniquet release was 6.58 and recovered to 6.75 within 20 minutes following release. No probe related adverse events were recorded. Conclusion. It is possible to directly measure skeletal muscle pH in human subjects over time. Tourniquet ischaemia results in a decrease in human skeletal muscle pH over time during short procedures. Cite this article: Bone Joint Res 2021;10(6):363–369

Aims. The purpose of this study was to compare the radiological outcomes of manual versus robotic-assisted medial unicompartmental knee arthroplasty (UKA). Methods. Postoperative radiological outcomes from 86 consecutive robotic-assisted UKAs (RAUKA group) from a single academic centre were retrospectively reviewed and compared to 253 manual UKAs (MUKA group) drawn from a prior study at our institution. Femoral coronal and sagittal angles (FCA, FSA), tibial coronal and sagittal angles (TCA, TSA), and implant overhang were radiologically measured to identify outliers. Results. When assessing the accuracy of RAUKAs, 91.6% of all alignment measurements and 99.2% of all overhang measurements were within the target range. All alignment and overhang targets were simultaneously met in 68.6% of RAUKAs. When comparing radiological outcomes between the RAUKA and MUKA groups, statistically significant differences were identified for combined outliers in FCA (2.3% vs 12.6%; p = 0.006), FSA (17.4% vs 50.2%; p < 0.001), TCA (5.8% vs 41.5%; p < 0.001), and TSA (8.1% vs 18.6%; p = 0.023), as well as anterior (0.0% vs 4.7%; p = 0.042), posterior (1.2% vs 13.4%; p = 0.001), and medial (1.2% vs 14.2%; p < 0.001) overhang outliers. Conclusion. Robotic system navigation decreases alignment and overhang outliers compared to manual UKA. Given the association between component placement errors and revision in UKA, this strong significant improvement in accuracy may improve implant survival. Level of Evidence: III. Cite this article: Bone Jt Open 2021;2-3:191–197

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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.

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Micromotion of the polyethylene (PE) inlay may contribute to backside PE wear in addition to articulate wear of total knee arthroplasty (TKA). Using radiostereometric analysis (RSA) with tantalum beads in the PE inlay, we evaluated PE micromotion and its relationship to PE wear.

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Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity.

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This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy.

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The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases.

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This prospective study reports longitudinal, within-patient, patient-reported outcome measures (PROMs) over a 15-year period following cemented single radius total knee arthroplasty (TKA). Secondary aims included reporting PROMs trajectory, 15-year implant survival, and patient attrition from follow-up.

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The aims were to assess whether joint-specific outcome after total knee arthroplasty (TKA) was influenced by implant design over a 12-year follow-up period, and whether patient-related factors were associated with loss to follow-up and mortality risk.

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The goal was to evaluate tibiofemoral knee joint kinematics during stair descent, by simulating the full stair descent motion in vitro. The knee joint kinematics were evaluated for two types of knee implants: bi-cruciate retaining and bi-cruciate stabilized. It was hypothesized that the bi-cruciate retaining implant better approximates native kinematics.

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The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients.

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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.

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Sagittal plane imbalance (SPI), or asymmetry between extension and flexion gaps, is an important issue in total knee arthroplasty (TKA). The purpose of this study was to compare SPI between kinematic alignment (KA), mechanical alignment (MA), and functional alignment (FA) strategies.

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With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

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The antidiabetic agent metformin inhibits fibrosis in various organs. This study aims to elucidate the effects of hyperglycaemia and metformin on knee joint capsule fibrosis in mice.

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The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution.

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The primary aim of this study was to compare the migration of the femoral and tibial components of the cementless rotating platform Attune and Low Contact Stress (LCS) total knee arthroplasty (TKA) designs, two years postoperatively, using radiostereometric analysis (RSA) in order to assess the risk of the development of aseptic loosening. A secondary aim was to compare clinical and patient-reported outcome measures (PROMs) between the designs.

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The aim of this study was to compare patient-reported outcomes (PROMs) following isolated anterior cruciate ligament reconstruction (ACLR), with those following ACLR and concomitant meniscal resection or repair.

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Accurate identification of the ankle joint centre is critical for estimating tibial coronal alignment in total knee arthroplasty (TKA). The purpose of the current study was to leverage artificial intelligence (AI) to determine the accuracy and effect of using different radiological anatomical landmarks to quantify mechanical alignment in relation to a traditionally defined radiological ankle centre.

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Knowledge on total knee arthroplasties (TKAs) in patients with a history of poliomyelitis is limited. This study compared implant survivorship and clinical outcomes among affected and unaffected limbs in patients with sequelae of poliomyelitis undergoing TKAs.

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This Delphi study assessed the challenges of diagnosing soft-tissue knee injuries (STKIs) in acute settings among orthopaedic healthcare stakeholders.

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We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry.

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The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral.

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The aim of this study was to evaluate the cost-effectiveness of arthroscopic partial meniscectomy versus physical therapy plus optional delayed arthroscopic partial meniscectomy in young patients aged under 45 years with traumatic meniscal tears.

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The purpose of this study was to assess mid-term survivorship following primary total knee arthroplasty (TKA) with Optetrak Logic components and identify the most common revision indications at a single institution.

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The primary objective of this study was to compare the five-year tibial component migration and wear between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts of the uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary objectives included clinical outcomes and patient-reported outcome measures (PROMs).

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Tibial tubercle osteotomy (TTO) facilitates surgical exposure and protects the extensor mechanism during revision total knee arthroplasty (rTKA). The purpose of this study was to determine the rates of bony union, complications, and reoperations following TTO during rTKA, to assess the functional outcomes of rTKA with TTO at two years’ minimum follow-up, and to identify the risk factors of failure.

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The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery.

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This study compared patient-reported outcomes of three total knee arthroplasty (TKA) designs from one manufacturer: one cruciate-retaining (CR) design, and two cruciate-sacrificing designs, anterior-stabilized (AS) and posterior-stabilized (PS).

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This multicentre retrospective observational study’s aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision.

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Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice.

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Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))?

Aims. The purpose of this study was to explore the correlation between femoral torsion and morphology of the distal femoral condyle in patients with trochlear dysplasia and lateral patellar instability. Methods. A total of 90 patients (64 female, 26 male; mean age 22.1 years (SD 7.2)) with lateral patellar dislocation and trochlear dysplasia who were awaiting surgical treatment between January 2015 and June 2019 were retrospectively analyzed. All patients underwent CT scans of the lower limb to assess the femoral torsion and morphology of the distal femur. The femoral torsion at various levels was assessed using the a) femoral anteversion angle (FAA), b) proximal and distal anteversion angle, c) angle of the proximal femoral axis-anatomical epicondylar axis (PFA-AEA), and d) angle of the AEA–posterior condylar line (AEA-PCL). Representative measurements of distal condylar length were taken and parameters using the ratios of the bianterior condyle, biposterior condyle, bicondyle, anterolateral condyle, and anteromedial condyle were calculated and correlated with reference to the AEA, using the Pearson Correlation coefficient. Results. The femoral torsion had a strong correlation with distal condylar morphology. The FAA was significantly correlated with the ratio of the bianterior condyle (r = 0.355; p = 0.009), the AEA-PCL angle (r = 0.340; p = 0.001) and the ratio of the anterolateral condyle and lateral condyle (ALC-LC) (r = 0.309; p = 0.014). The PFA-AEA angle was also significantly correlated with the ratio of the bianterior condyle (r = 0.319; p = 0.008), the AEA-PCL angle (r = 0.231; p = 0.031), and the ratio of ALC-LC (r = 0.261; p = 0.034). In addition, the bianterior condyle ratio showed a significant correlation with the biposterior condyle ratio (r = -0.324; p = 0.027) and the AEA-PCL angle (r = 0.342; p = 0.021). Conclusion. Increased femoral torsion correlated with a prominent anterolateral condyle and a shorter posterolateral condyle compared with the medial condyle. The deformities of the anterior and posterior condyles are combined deformities rather than being isolated and individual deformities in patients with trochlear dysplasia and patella instability. Cite this article: Bone Joint J 2020;102-B(7):868–873

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Conflicting clinical results are reported for the ATTUNE Total Knee Arthroplasty (TKA). This randomized controlled trial (RCT) evaluated five-year follow-up results comparing cemented ATTUNE and PFC-Sigma cruciate retaining TKAs, analyzing component migration as measured by radiostereometric analysis (RSA), clinical outcomes, patient-reported outcome measures (PROMs), and radiological outcomes.

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To evaluate whether low-intensity pulsed ultrasound (LIPUS) accelerates bone healing at osteotomy sites and promotes functional recovery after open-wedge high tibial osteotomy (OWHTO).

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Loosening of components after total knee arthroplasty (TKA) can be associated with the development of radiolucent lines (RLLs). The aim of this study was to assess the rate of formation of RLLs in the cemented original design of the ATTUNE TKA and their relationship to loosening.

Aims. This study aims to determine the proportion of patients with end-stage knee osteoarthritis (OA) possibly suitable for partial (PKA) or combined partial knee arthroplasty (CPKA) according to patterns of full-thickness cartilage loss and anterior cruciate ligament (ACL) status. Methods. A cross-sectional analysis of 300 consecutive patients (mean age 69 years (SD 9.5, 44 to 91), mean body mass index (BMI) 30.6 (SD 5.5, 20 to 53), 178 female (59.3%)) undergoing total knee arthroplasty (TKA) for Kellgren-Lawrence grade ≥ 3 knee OA was conducted. The point of maximal tibial bone loss on preoperative lateral radiographs was determined as a percentage of the tibial diameter. At surgery, Lachman’s test and ACL status were recorded. The presence of full-thickness cartilage loss within 16 articular surface regions (two patella, eight femoral, six tibial) was recorded. Results. According to articular cartilage loss and ACL status, 195/293 (67%) were suitable for PKA or CPKA: medial unicompartmental knee arthroplasty (UKA) 97/293 (33%); lateral UKA 25 (9%); medial bicompartmental arthroplasty 31 (11%); lateral bicompartmental arthroplasty 12 (4%); bicondylar-UKA 23 (8%); and patellofemoral arthroplasty (PFA) seven (2%). The ACL was intact in 166 (55%), frayed in 82 (27%), disrupted in 12 (4%), and absent in 33 (11%). Lachman testing was specific (97%) but poorly sensitive (38%) for disrupted/absent ACLs. The point of maximal tibial bone loss showed good interclass correlation (ICC 0.797, 0.73 to 0.85 95% confidence interval (CI); p < 0.001) and was more posterior when the ACL was absent. Maximum tibial bone loss occurring at > 55% of the anterior to posterior distance predicted ACL absence with 93% sensitivity and 91% specificity (area under the curve 0.97 (0.94 to 0.99 95% CI; p < 0.001). Conclusion. ACL status can be reliably determined from a lateral radiograph using the location of maximal tibial bone loss. According to regions of cartilage loss and ACL status, two-thirds of patients with end-stage knee OA could potentially be treated with PKA or CPKA. Cite this article: Bone Joint J 2020;102-B(6):716–726

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

Objectives. The aim of this study was to investigate the biomechanical effect of the anterolateral ligament (ALL), anterior cruciate ligament (ACL), or both ALL and ACL on kinematics under dynamic loading conditions using dynamic simulation subject-specific knee models. Methods. Five subject-specific musculoskeletal models were validated with computationally predicted muscle activation, electromyography data, and previous experimental data to analyze effects of the ALL and ACL on knee kinematics under gait and squat loading conditions. Results. Anterior translation (AT) significantly increased with deficiency of the ACL, ALL, or both structures under gait cycle loading. Internal rotation (IR) significantly increased with deficiency of both the ACL and ALL under gait and squat loading conditions. However, the deficiency of ALL was not significant in the increase of AT, but it was significant in the increase of IR under the squat loading condition. Conclusion. The results of this study confirm that the ALL is an important lateral knee structure for knee joint stability. The ALL is a secondary stabilizer relative to the ACL under simulated gait and squat loading conditions. Cite this article: Bone Joint Res 2019;8:509–517

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No predictive model has been published to forecast operating time for total knee arthroplasty (TKA). The aims of this study were to design and validate a predictive model to estimate operating time for robotic-assisted TKA based on demographic data, and evaluate the added predictive power of CT scan-based predictors and their impact on the accuracy of the predictive model.

Aims

Meniscal allograft transplantation (MAT) for patients with symptomatic meniscal loss has demonstrated good clinical results and survivorship. Factors that affect both functional outcome and survivorship have been reported in the literature. These are typically single-centre case series with relatively small numbers and conflicting results. Our aim was to describe an international, two-centre case series, and identify factors that affect both functional outcome and survival.

Objectives. Posterior condylar offset (PCO) and posterior tibial slope (PTS) are critical factors in total knee arthroplasty (TKA). A computational simulation was performed to evaluate the biomechanical effect of PCO and PTS on cruciate retaining TKA. Methods. We generated a subject-specific computational model followed by the development of ± 1 mm, ± 2 mm and ± 3 mm PCO models in the posterior direction, and -3°, 0°, 3° and 6° PTS models with each of the PCO models. Using a validated finite element (FE) model, we investigated the influence of the changes in PCO and PTS on the contact stress in the patellar button and the forces on the posterior cruciate ligament (PCL), patellar tendon and quadriceps muscles under the deep knee-bend loading conditions. Results. Contact stress on the patellar button increased and decreased as PCO translated to the anterior and posterior directions, respectively. In addition, contact stress on the patellar button decreased as PTS increased. These trends were consistent in the FE models with altered PCO. Higher quadriceps muscle and patellar tendon force are required as PCO translated in the anterior direction with an equivalent flexion angle. However, as PTS increased, quadriceps muscle and patellar tendon force reduced in each PCO condition. The forces exerted on the PCL increased as PCO translated to the posterior direction and decreased as PTS increased. Conclusion. The change in PCO alternatively provided positive and negative biomechanical effects, but it led to a reduction in a negative biomechanical effect as PTS increased. Cite this article: K-T. Kang, Y-G. Koh, J. Son, O-R. Kwon, J-S. Lee, S. K. Kwon. A computational simulation study to determine the biomechanical influence of posterior condylar offset and tibial slope in cruciate retaining total knee arthroplasty. Bone Joint Res 2018;7:69–78. DOI: 10.1302/2046-3758.71.BJR-2017-0143.R1

Aims

The purpose of this study was to compare the clinical outcomes, mortalities, implant survival rates, and complications of total knee arthroplasty (TKA) in patients with or without hepatitis B virus (HBV) infection over at least ten years of follow-up.

The kinematic alignment (KA) approach to total knee arthroplasty (TKA) has recently increased in popularity. Accordingly, a number of derivatives have arisen and have caused confusion. Clarification is therefore needed for a better understanding of KA-TKA. Calipered (or true, pure) KA is performed by cutting the bone parallel to the articular surface, compensating for cartilage wear. In soft-tissue respecting KA, the tibial cutting surface is decided parallel to the femoral cutting surface (or trial component) with in-line traction. These approaches are categorized as unrestricted KA because there is no consideration of leg alignment or component orientation. Restricted KA is an approach where the periarthritic joint surface is replicated within a safe range, due to concerns about extreme alignments that have been considered ‘alignment outliers’ in the neutral mechanical alignment approach. More recently, functional alignment and inverse kinematic alignment have been advocated, where bone cuts are made following intraoperative planning, using intraoperative measurements acquired with computer assistance to fulfill good coordination of soft-tissue balance and alignment. The KA-TKA approach aims to restore the patients’ own harmony of three knee elements (morphology, soft-tissue balance, and alignment) and eventually the patients’ own kinematics. The respective approaches start from different points corresponding to one of the elements, yet each aim for the same goal, although the existing implants and techniques have not yet perfectly fulfilled that goal.

Aims

Higher osteoblastic bone activity is expected in aseptic loosening and painful unicompartmental knee arthroplasty (UKA). However, insights into normal bone activity patterns after medial UKAs are lacking. The aim of this study was to identify the evolution in bone activity pattern in well-functioning medial mobile-bearing UKAs.

Aims. We aimed to investigate factors related to the technique of medial opening wedge high tibial osteotomy which might predispose to the development of a lateral hinge fracture. Patients and Methods. A total of 71 patients with 82 osteotomies were included in the study. Their mean age was 62.9 years (37 to 80). The classification of the type of osteotomy was based on whether it extended beyond the fibular head. The level of the osteotomy was classified according to the height of its endpoint. Results. At a mean follow-up of 20 months (6 to 52), a total of 15 lateral hinge fractures (18.3%) were identified. A sufficient osteotomy, in which both anterior and posterior tibial cortices were involved with extension into the lateral aspect of the plateau in relation to an anteroposterior line tangential to the medial edge of the fibular head in the CT axial plane, was seen in 48 knees (71.6%) in those without a lateral hinge fracture and in seven (46.7%) in those with a lateral hinge fracture. An osteotomy which ended above the level of the fibular head was seen in nine (13.4%) of the knees without a lateral hinge fracture and seven (46.7%) of the those with a lateral hinge fracture. There was a significant relationship between the absence of a lateral hinge fracture and both a sufficient osteotomy and one whose endpoint was at the level of the fibular head (p = 0.0451 and p = 0.0214, respectively). Conclusion. A sufficient osteotomy involving both the anterior and posterior cortices, whose endpoint is at the level of the fibular head, should be performed when undertaking a medial opening wedge high tibial osteotomy if a lateral hinge fracture is to be avoided as a complication. Cite this article: Bone Joint J 2017;99-B:887–93

Aims

One of the main causes of tibial revision surgery for total knee arthroplasty is aseptic loosening. Therefore, stable fixation between the tibial component and the cement, and between the tibial component and the bone, is essential. A factor that could influence the implant stability is the implant design, with its different variations. In an existing implant system, the tibial component was modified by adding cement pockets. The aim of this experimental in vitro study was to investigate whether additional cement pockets on the underside of the tibial component could improve implant stability. The relative motion between implant and bone, the maximum pull-out force, the tibial cement mantle, and a possible path from the bone marrow to the metal-cement interface were determined.

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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.

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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.

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The 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.

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This study aimed to investigate the relationship between changes in patellar height and clinical outcomes at a mean follow-up of 7.7 years (5 to 10) after fixed-bearing posterior-stabilized total knee arthroplasty (PS-TKA).

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Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but the solid metal implants disrupt the natural distribution of stress and strain which can lead to bone loss over time. This generates problems if the implant needs to be revised. This study investigates whether titanium lattice UKA and TKA implants can maintain natural load transfer in the proximal tibia.

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It is unknown whether gap laxities measured in robotic arm-assisted total knee arthroplasty (TKA) correlate to load sensor measurements. The aim of this study was to determine whether symmetry of the maximum medial and lateral gaps in extension and flexion was predictive of knee balance in extension and flexion respectively using different maximum thresholds of intercompartmental load difference (ICLD) to define balance.

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

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The patient-acceptable symptom state (PASS) is a level of wellbeing, which is measured by the patient. The aim of this study was to determine if the proportion of patients who achieved an acceptable level of function (PASS) after medial unicompartmental knee arthroplasty (UKA) was different based on the status of the anterior cruciate ligament (ACL) at the time of surgery.

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Robotic-assisted total knee arthroplasty (RA-TKA) is theoretically more accurate for component positioning than TKA performed with mechanical instruments (M-TKA). Furthermore, the ability to incorporate soft-tissue laxity data into the plan prior to bone resection should reduce variability between the planned polyethylene thickness and the final implanted polyethylene. The purpose of this study was to compare accuracy to plan for component positioning and precision, as demonstrated by deviation from plan for polyethylene insert thickness in measured-resection RA-TKA versus M-TKA.

Aims

The aim of this study was to compare the clinical outcomes of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) during the first six weeks and at one year postoperatively.

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

We have examined the relationship between the size of the flexion gap and the anterior translation of the tibia in flexion during implantation of a posterior cruciate ligament (PCL)-retaining BalanSys total knee replacement (TKR). In 91 knees, the flexion gap and anterior tibial translation were measured intra-operatively using a custom-made, flexible tensor-spacer device. The results showed that for each increase of 1 mm in the flexion gap in the tensed knee a mean anterior tibial translation of 1.25 mm (SD 0.79, 95% confidence interval 1.13 to 1.37) was produced. When implanting a PCL-retaining TKR the surgeon should be aware that the tibiofemoral contact point is related to the choice of thickness of the polyethylene insert. An additional thickness of polyethylene insert of 2 mm results in an approximate increase in tibial anterior translation of 2.5 mm while the flexed knee is distracted with a force of between 100 N and 200 N

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The objective of this study is to assess the use of ultrasound (US) as a radiation-free imaging modality to reconstruct 3D anatomy of the knee for use in preoperative templating in knee arthroplasty.

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Ideal component sizing may be difficult to achieve in unicompartmental knee arthroplasty (UKA). Anatomical variants, incremental implant size, and a reduced surgical exposure may lead to over- or under-sizing of the components. The purpose of this study was to compare the accuracy of UKA sizing with robotic-assisted techniques versus a conventional surgical technique.

Aims

Recent total knee arthroplasty (TKA) designs have featured more anatomical morphologies and shorter tibial keels. However, several reports have raised concerns about the impact of these modifications on implant longevity. The aim of this study was to report the early performance of a modern, cemented TKA design.

We have quantitatively documented the insertion geometry of the main stabilising structures of the posterolateral corner of the knee in 34 human cadavers. The lateral collateral ligament inserted posterior (4.6 mm, . sd. 2) and proximal (1.3 mm, . sd. 3.6) to the lateral epicondyle of the femur and posterior (8.1 mm, . sd. 3.2) to the anterior point of the head of the fibula. On the femur, the popliteus tendon inserted distally (11 mm, . sd. 0.8) and either anterior or posterior (mean 0.84 mm anterior, . sd. 4) to the lateral collateral ligament. The popliteofibular ligament inserted distal (1.3 mm, . sd. 1.2) and anterior (0.5 mm, . sd. 2.0) to the tip of the styloid process of the fibula. The ligaments had a consistent pattern of insertion and, despite the variation between specimens, the standard deviations were less than the typical size of drill hole used in reconstruction of the posterolateral corner. The data provided in this study can be used in the anatomical repair and reconstruction of this region of the knee

A total of 22 patients with a tibial avulsion fracture involving the insertion of the posterior cruciate ligament (PCL) with grade II or III posterior laxity were reduced and fixed arthroscopically using routine anterior and double posteromedial portals. A double-strand Ethibond suture was inserted into the joint and wrapped around the PCL from anterior to posterior to secure the ligament above the avulsed bony fragment. Two tibial bone tunnels were created using the PCL reconstruction guide, aiming at the medial and lateral borders of the tibial bed. The ends of the suture were pulled out through the bone tunnels and tied over the tibial cortex between the openings of the tunnels to reduce and secure the bony fragment. Satisfactory reduction of the fracture was checked arthroscopically and radiographically. The patients were followed-up for a mean of 24.5 months (19 to 28). Bone union occurred six weeks post-operatively. At final follow-up, all patients had a negative posterior drawer test and a full range of movement. KT-1000 arthrometer examination showed that the mean post-operative side-to-side difference improved from 10.9 mm (standard deviation (. sd. ) 0.7) pre-operatively to 1.5 mm (. sd. 0.6) (p = 0.001). The mean Tegner and the International Knee Documentation Committee scores improved significantly (p = 0.001). The mean Lysholm score at final follow-up was 92.0 (85 to 96). We conclude that this technique is convenient, reliable and minimally invasive and successfully restores the stability and function of the knee. Cite this article: Bone Joint J 2015;97-B:1220–5

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

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

Meniscal injuries are common and often induce knee pain requiring surgical intervention. To develop effective strategies for meniscus regeneration, we hypothesized that a minced meniscus embedded in an atelocollagen gel, a firm gel-like material, may enhance meniscus regeneration through cell migration and proliferation in the gel. Hence, the objective of this study was to investigate cell migration and proliferation in atelocollagen gels seeded with autologous meniscus fragments in vitro and examine the therapeutic potential of this combination in an in vivo rabbit model of massive meniscus defect.

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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.

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The objective of this study was to compare the two-year migration pattern and clinical outcomes of a total knee arthroplasty (TKA) with an asymmetrical tibial design (Persona PS) and a well-proven TKA with a symmetrical tibial design (NexGen LPS).

The appearance of the ‘grand-piano sign’ on the anterior resected surface of the femur has been considered to be a marker for correct femoral rotational alignment during total knee replacement. Our study was undertaken to assess quantitatively the morphological patterns on the resected surface after anterior femoral resection with various angles of external rotation, using a computer-simulation technique. A total of 50 right distal femora with varus osteoarthritis in 50 Korean patients were scanned using computerised tomography. Computer image software was used to simulate the anterior femoral cut, which was applied at an external rotation of 0°, 3° and 6° relative to the posterior condylar axis, and parallel to the surgical and clinical epicondylar axes in each case. The morphological patterns on the resected surface were quantified and classified as the ‘grand-piano sign’, ‘the boot sign’ and the ‘butterfly sign’. The surgeon can use the analogy of these quantified sign patterns to ensure that a correct rotational alignment has been obtained intra-operatively