Aims. 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). Methods. We retrospectively evaluated knee radiographs of 165 knees, which underwent fixed-bearing PS-TKA with patella resurfacing. The incidence of patella baja and changes in patellar height over a minimum of five years of follow-up were determined using Insall-Salvati ratio (ISR) measurement. We examined whether patella baja (ISR < 0.8) at final follow-up affected clinical outcomes, knee joint range of motion (ROM), and Knee Society Score (KSS). We also assessed inter- and intrarater reliability of ISR measurements and focused on the relationship between patellar height reduction beyond measurement error and clinical outcomes. Results. The ISR gradually decreased over five years after TKA, and finally 33 patients (20.0%) had patella baja. Patella baja at the final follow-up was not related to passive knee ROM or KSS. Interestingly, when we divided into two groups - patella baja and patella normal-alta (ISR ≥ 0.8) - the patella baja group already had a lower patellar height before surgery, compared with the patella normal-alta group. The ISR measurement error in this study was 0.17. Both passive knee flexion and KSS were significantly decreased in the group with a decrease in ISR of ≥ 0.17 at final follow-up. Conclusion. Patellar height gradually decreased over five years of follow-up after TKA. The reduction in patellar height beyond measurement error following TKA was associated with lower clinical outcomes. Cite this article: Bone Jt Open 2021;2(12):1075–1081

We have studied the concept of posterior condylar offset and the importance of its restoration on the maximum range of knee flexion after posterior-cruciate-ligament-retaining total knee replacement (TKR). We measured the difference in the posterior condylar offset before and one year after operation in 69 patients who had undergone a primary cruciate-sacrificing mobile bearing TKR by one surgeon using the same implant and a standardised operating technique. In all the patients true pre- and post-operative lateral radiographs had been taken. The mean pre- and post-operative posterior condylar offset was 25.9 mm (21 to 35) and 26.9 mm (21 to 34), respectively. The mean difference in posterior condylar offset was + 1 mm (−6 to +5). The mean pre-operative knee flexion was 111° (62° to 146°) and at one year postoperatively, it was 107° (51° to 137°). There was no statistical correlation between the change in knee flexion and the difference in the posterior condylar offset after TKR (Pearson correlation coefficient r = −0.06, p = 0.69)

We describe a symptomatic, progressive restriction of knee flexion due to an accessory quadriceps femoris in a nine-year-old girl. There was no history or findings of post-injection fibrosis, nor any obvious swelling of the affected quadriceps. At arthroscopy no intra-articular pathology was found. An accessory ‘quinticeps femoris’ was diagnosed by ultrasonography and MRI. Following excision of the muscle and tendon full flexion of the knee was regained and there was no recurrence of the contracture

In an initial randomised controlled trial (RCT) we segregated 180 patients to one of two knee positions following total knee replacement (TKR): six hours of knee flexion using either a jig or knee extension. Outcome measures included post-operative blood loss, fall in haemoglobin, blood transfusion requirements, knee range of movement, limb swelling and functional scores. A second RCT consisted of 420 TKR patients randomised to one of three post-operative knee positions: flexion for three or six hours post-operatively, or knee extension. Positioning of the knee in flexion for six hours immediately after surgery significantly reduced blood loss (p = 0.002). There were no significant differences in post-operative range of movement, swelling, pain or outcome scores between the various knee positions in either study. Post-operative knee flexion may offer a simple and cost-effective way to reduce blood loss and transfusion requirements following TKR. We also report a cautionary note regarding the potential risks of prolonged knee flexion for more than six hours observed during clinical practice in the intervening period between the two trials, with 14 of 289 patients (4.7%) reporting lower limb sensory neuropathy at their three-month review. Cite this article: Bone Joint J 2014;96-B:201–9

Total knee replacement and high tibial osteotomy are common orthopaedic operations with low complication rates. Such surgery is in close proximity to the popliteal artery (PA), the behaviour of which during flexion of the knee is poorly understood. We used Duplex ultrasonography to determine the distance of the PA from the posterior tibial surface at 0° and 90° of flexion in 100 knees. When the knee was flexed the PA was closer to the posterior tibial surface at 1 to 1.5 cm below the joint line in 24% and at 1.5 to 2 cm below the joint line in 15%. There was a high branching anterior tibal artery in 6% of knees. We provide an anatomical account to help to explain our findings by using cadaver dissections, arteriography and static MRI studies

This prospective randomised controlled double-blind trial compared two types of PFC Sigma total knee replacement (TKR), differing in three design features aimed at improving flexion. The outcome of a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) was compared with that of a high-flexion rotating-platform posterior-stabilised design (RP-F) at one year after TKR.

The study group of 77 patients with osteoarthritis of the knee comprised 37 men and 40 women, with a mean age of 69 years (44.9 to 84.9). The patients were randomly allocated either to the FB-S or the RP-F group and assessed pre-operatively and at one year post-operatively. The mean post-operative non-weight-bearing flexion was 107° (95% confidence interval (CI) 104° to 110°)) for the FB-S group and 113° (95% CI 109° to 117°) for the RP-F group, and this difference was statistically significant (p = 0.032). However, weight-bearing range of movement during both level walking and ascending a slope as measured during flexible electrogoniometry was a mean of 4° lower in the RP-F group than in the FB-S group, with 58° (95% CI 56° to 60°) versus 54° (95% CI 51° to 57°) for level walking (p = 0.019) and 56° (95% CI 54° to 58°) versus 52° (95% CI 48° to 56°) for ascending a slope (p = 0.044). Further, the mean post-operative pain score of the Western Ontario and McMaster Universities Osteoarthritis Index was significantly higher in the RP-F group (2.5 (95% CI 1.5 to 3.5) versus 4.2 (95% CI 2.9 to 5.5), p = 0.043).

Although the RP-F group achieved higher non-weight-bearing knee flexion, patients in this group did not use this during activities of daily living and reported more pain one year after surgery.

We report the case of a child with cerebral palsy and spastic diplegia treated for bilateral fixed flexion of the knee by bilateral hamstring lengthening. An attempt to straighten the legs from 90 degrees to 20 degrees flexion damaged the sciatic nerve. There are no objective means of estimating how much deformity can be reduced safely. We present a method of calculating the extra strain in the sciatic nerve produced by reducing a flexion deformity. The result, combined with clinical judgement, provides guidelines for safe corrective surgery.

This study examined pre-operative measures to predict post-operative biomechanical outcomes in total knee arthroplasty (TKA) patients. Twenty-eight patients (female=12/male=16, age=63.6±6.9, BMI=29.9±7.4 kg/m2) with knee osteoarthritis scheduled to undergo TKA were included. All surgeries were performed by the same surgeon (GD) with a subvastus approach. Patients visited the gait lab within one-month prior to surgery and 12 months following surgery. At the gait lab, patients completed the knee injury and osteoarthritis outcome score (KOOS), a timed up and go (TUG), maximum knee flexion and extension strength evaluation, and a walking task. Variables of interest included the five KOOS sub-scores, TUG time, maximum knee flexion and extension strength normalized to body weight, walking speed, and peak knee biomechanics variables (flexion angle, abduction moment, power absorption). A Pearson's correlation was used to identify significantly correlated variables which were then inputted into a multiple regression. No assumption violations for the multiple regression existed for any variables. Pre-operative knee flexion and extension strength, TUG time, and age were used in the multiple regression. The multiple regression model statistically significantly predicted peak knee abduction moment, post-operative walking speed, and post-operative knee flexion strength. All four variables added statistically significantly to the prediction p<.05. Pre-operative KOOS values did not correlate with any biomechanical indicators of post-operative success. Age, pre-operative knee flexion and extension strength, and TUG times predicted peak knee abduction moment, which is associated with medial knee joint loading. These findings stress the importance of pre-surgery condition, as stronger individuals achieved better post-operative biomechanical outcomes. Additionally, younger patients had better outcomes, suggesting that surgeons should not delay surgery in younger patients. This delay in surgery may prevent patients from achieving optimal outcomes. Future studies should utilize a hierarchical multiple regression to identify which variables are most predictive

Individuals with multi-compartment knee osteoarthritis (KOA) frequently experience challenges in activities of daily living (ADL) such as stair ambulation. The Levitation “Tri-Compartment Offloader” (TCO) knee brace was designed to reduce pain in individuals with multicompartment KOA. This brace uses novel spring technology to reduce tibiofemoral and patellofemoral forces via reduced quadriceps forces. Information on brace utility during stair ambulation is limited. This study evaluated the effect of the TCO during stair descent in patients with multicompartment KOA by assessing knee flexion moments (KFM), quadriceps activity and pain. Nine participants (6 male, age 61.4±8.1 yrs; BMI 30.4±4.0 kg/m2) were tested following informed consent. Participants had medial tibiofemoral and patellofemoral OA (Kellgren-Lawrence grades two to four) diagnosed by an orthopaedic surgeon. Joint kinetics and muscle activity were evaluated during stair descent to compare three bracing conditions: 1) without brace (OFF); 2) brace in low power (LOW); and 3) brace in high power (HIGH). The brace spring engages from 60° to 120° and 15° to 120° knee flexion in LOW and HIGH, respectively. Individual brace size and fit were adjusted by a trained researcher. Participants performed three trials of step-over-step stair descent for each bracing condition. Three-dimensional kinematics were acquired using an 8-camera motion capture system. Forty-one spherical reflective markers were attached to the skin (on each leg and pelvis segment) and 8 markers on the brace. Ground reaction forces and surface EMG from the vastus medialis (VM) and vastus lateralis (VL) were collected for the braced leg. Participants rated knee pain intensity performing the task following each bracing condition on a 10cm Visual Analog Scale ranging from “no pain” (0) to “worst imaginable pain” (100). Resultant brace and knee flexion angles and KFM were analysed during stair contact for the braced leg. The brace moment was determined using brace torque-angle curves and was subtracted from the calculated KFM. Resultant moments were normalized to bodyweight and height. Peak KFMs were calculated for the loading response (Peak1) and push-off (Peak2) phases of support. EMG signals were normalized and analysed during stair contact using wavelet analysis. Signal intensities were summed across wavelets and time to determine muscle power. Results were averaged across all 3 trials for each participant. Paired T-tests were used to determine differences between bracing conditions with a Bonferroni adjustment for multiple comparisons (α=0.025). Peak KFM was significantly lower compared to OFF with the brace worn in HIGH during the push-off phase (p Table 1: Average peak knee flexion moments, quadriceps muscle power and knee pain during stair descent in 3 brace conditions (n=9). Quadriceps activity, knee flexion moments and pain were significantly reduced with TCO brace wear during stair descent in KOA patients. These findings suggest that the TCO assists the quadriceps to reduce KFM and knee pain during stair descent. This is the first biomechanical evidence to support use of the TCO to reduce pain during an ADL that produces especially high knee forces and flexion moments. For any figures or tables, please contact the authors directly

Aims. Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology. Methods. This prospective study included 30 consecutive patients undergoing robotic-assisted TKA using the Stryker PS Triathlon implant with functional alignment. Intraoperative soft-tissue balance was assessed using sensor-guided technology after definitive component implantation; soft-tissue balance was defined as intercompartmental pressure difference (ICPD) of < 15 psi. Medial and lateral compartment pressures were recorded at 10°, 45°, and 90° of knee flexion. This study included 18 females (60%) and 12 males (40%) with a mean age of 65.2 years (SD 9.3). Mean preoperative hip-knee-ankle deformity was 6.3° varus (SD 2.7°). Results. TKA with functional alignment achieved balanced medial and lateral compartment pressures at 10° (25.0 psi (SD 6.1) vs 23.1 psi (SD 6.7), respectively; p = 0.140), 45° (21.4 psi (SD 5.9) vs 20.6 psi (SD 5.9), respectively; p = 0.510), and 90° (21.2 psi (SD 7.1) vs 21.6 psi (SD 9.0), respectively; p = 0.800) of knee flexion. Mean ICPD was 6.1 psi (SD 4.5; 0 to 14) at 10°, 5.4 psi (SD 3.9; 0 to 12) at 45°, and 4.9 psi (SD 4.45; 0 to 15) at 90° of knee flexion. Mean postoperative limb alignment was 2.2° varus (SD 1.0°). Conclusion. TKA using the functional alignment achieves balanced mediolateral soft-tissue tension through the arc of knee flexion as assessed using intraoperative pressure-sensor technology. Further clinical trials are required to determine if TKA with functional alignment translates to improvements in patient satisfaction and outcomes compared to conventional alignment techniques. Cite this article: Bone Joint J 2021;103-B(3):507–514

Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship

The aim is to investigate if there is a relation between patellar height and knee flexion angle. For this purpose we retrospectively evaluated the radiographs of 500 knees presented for a variety of reasons. We measure knee flexion angle using a computer-generated goniometer. Patellar height was determined using computer generated measurement for the selected ratios, namely, the Insall–Salvati (I/S), Caton–Deschamps (C/D) and Blackburne–Peel (B/P) indices and Modified I/S Ratio. A search of an NHS hospital database was made to identify the knee x rays for patients who were below the age of forty. A senior knee surgeon (DC) supervised three trainee trauma and orthopaedics doctors (HA, JM, ES) working on this research. Measurements were made on the Insall–Salvati (I/S), Caton–Deschamps (C/D) and Blackburne–Peel (B/P) indices and Modified I/S Ratio. The team leader then categorised the experimental measurement of patients’ knee flexion angle into three groups. This categorisation was according to the extent of knee flexion. The angles were specifically, 10.1 to 20, 20.1 to 30, and 30.1 to 40 degrees of knee flexion. Out of the five-hundred at the start of the investigation, four hundred and eighteen patients were excluded because they had had either an operation on the knee or traumatic fracture that was treated conservatively

To investigate changes in quadriceps and hamstrings muscle groups during sustained isokinetic knee flexion and extension. 125 paediatric participants (45 males and 80 females, mean age 14.2 years) were divided into two groups: participants with a confirmed ACL tear (ACLi, n = 64), and puberty- and activity-level matched control participants with no prior history of knee injuries (CON, n = 61). Participants completed a series of 44 repetitions of isokinetic knee flexion and extension at 90 deg/ sec using a Biodex dynamometer (Biodex Medical Systems Inc, Shirley, New York). Surface EMG sensors (Delsys Incorporated, Natick, MA) simultaneously recorded the quadriceps and hamstring activations. Muscle function was assessed as the change in quadriceps activation and extension torque were calculated using the percent difference between the mean of the first five trials, and the mean of the last five trials. ACLi participants had significantly higher percent change in quadriceps activation for both healthy and injured legs, in comparison to CON dominant leg. As such, the healthy leg of the ACLi participants is activating significantly more than their health matched controls, while also demonstrating reduced muscular endurance (less torque in later repetitions). Therefore, we conclude that the non-injured limb of the ACLi participant is not performing as a healthy limb. Since return to activity clearance following ACLi implies return to sport against age- and activity matched opponents, clearing young athletes based on the non-injured contralateral limb may put them at greater risk of reinjury

Introduction. There is a lack of evidence-based treatments for patients with chronic pain after total knee arthroplasty (TKA). It is well-established that knee extensor and flexor muscle strength are markedly impaired following TKA, but no studies have examined muscle strength and power in patients with chronic pain after TKA. Therefore, the aim was to investigate if neuromuscular exercises and pain neuroscience education (PNE) were superior to PNE alone for improvement of muscle strength and power in patients with chronic pain after TKA. Method. This report presents the exploratory analysis of a randomized controlled trial (NCT03886259). Participants with chronic moderate-to-severe average daily pain intensity and no signs of prosthesis failure at least one year after primary TKA were included. Participants were randomized to receive either supervised neuromuscular exercise and PNE or the same PNE sessions alone. The outcomes were changes from baseline to 12-months for peak leg extension power and maximum muscle strength, measured during maximal voluntary isometric contractions, for the knee extensors and flexors. Result. Sixty-nine participants (age 62.2±7.2, 40 females) were included. No between-group differences were observed for peak leg extension power (difference 13.6 Watts, 95% CI -22.2 to 49.3), maximum knee extensor muscle strength (difference -20.9 Newtons, 95% CI -65.8 to 24.0) or maximum knee flexor muscle strength (difference 8.6 Newtons, 95% CI -11.9 to 29.1). Peak leg extension power (26.3 Watts, 95% CI 4.3 to 48.3) and maximum knee flexor muscle strength (19.7 Newtons, 95% CI 7.6 to 31.9) improved significantly in the neuromuscular exercise and PNE group with no significant improvements observed in the PNE alone group. Conclusion. Neuromuscular exercise and PNE did not improve muscle strength and power compared to PNE alone in patients with chronic pain after TKA. Acknowledgements. This study was funded by the Danish Rheumatism Association, the Svend Andersen Foundation and Lions Club Denmark

Ligament reconstruction following multi-ligamentous knee injuries involves graft fixation in bone tunnels using interference screws (IS) or cortical suspensory systems. Risks of IS fixation include graft laceration, cortical fractures, prominent hardware, and inability to adjust tensioning once secured. Closed loop suspensory (CLS) fixation offers an alternative with fewer graft failures and improved graft-to-tunnel incorporation. However, graft tensioning cannot be modified to accommodate errors in tunnel length evaluation. Adjustable loop suspensory (ALS) devices (i.e., Smith & Nephew Ultrabutton) address these concerns and also offer the ability to sequentially tighten each graft, as needed. However, ALS devices may lead to increased graft displacement compared to CLS devices. Therefore, this study aims to report outcomes in a large clinical cohort of patients using both IS and CLS fixation. A retrospective review of radiographic, clinical, and patient-reported outcomes following ligament reconstruction from a Level 1 trauma centre was completed. Eligible patients were identified via electronic medical records using ICD-10 codes. Inclusion criteria were patients 18 years or older undergoing ACL, PCL, MCL, and/or LCL reconstruction between January 2018 and 2020 using IS and/or CLS fixation, with a minimum of six-month post-operative follow-up. Exclusion criteria were follow-up less than six months, incomplete radiographic imaging, and age less than 18 years. Knee dislocations (KD) were classified using the Schenck Classification. The primary outcome measure was implant removal rate. Secondary outcomes were revision surgery rate, deep infection rate, radiographic fixation failure rate, radiographic malposition, Lysholm and Tegner scores, clinical graft failure, and radiographic graft failure. Radiographic malposition was defined as implants over 5 mm off bone or intraosseous deployment of the suspensory fixation device. Clinical graft failure was defined as a grade II or greater Lachman, posterior drawer, varus opening at 20° of knee flexion, and/or valgus opening at 20° of knee flexion. Radiographic failure was defined when over 5 mm, 3.2 mm, and/or 2.7 mm of side-to-side difference occurred using PCL gravity stress views, valgus stress views, and/or varus stress views, respectively. Descriptive statistics were used. Sixty-three consecutive patients (mean age = 41 years, range = 19-58) were included. A total of 266 CLS fixation with Ultrabuttons and 135 IS were used. Mean follow-up duration was 383 days. Most injuries were KD type II and III. Graft revision surgery rate was 1.5%. Intraosseous deployment occurred in 6.2% and 17% had implants secured in soft tissue, rather than on bone. However, the implant removal rate was only 6.2%. Radiographic PCL gravity stress views demonstrated an average of 1.2 mm of side-to-side difference with 6.2% meeting criteria for radiographic failure. A single patient met radiographic failure criteria for collateral grafts. Mean Lysholm and Tegner scores were 87.3 and 4.4, respectively, with follow-up beyond one year. Both IS and CLS fixation demonstrate an extremely low revision surgery rate, a high rate of implant retention, excellent radiographic stability, and satisfactory patient-reported outcome scores. Incorrect implant deployment was seen in a total of 17% of patients, yet none required implant removal. A single patient required graft revision due to implant failure

Abstract. Introduction. The postoperative inflammatory response may be implicated in the aetiology of patient dissatisfaction following Total Knee Arthroplasty. Robotic-arm assisted TKA has been associated with reduced bone and soft tissue trauma. The objective of this Randomised Controlled Trial was to compare the inflammatory response in conventional Jig-based versus robotic arm-assisted TKA and examine the relationship with patient reported outcome measures and functional outcomes. Methodology. 30 patients with knee osteoarthritis were randomised to either conventional or robotic-arm assisted TKA. Blood samples were collected for up to 28 days post-operatively and intraarticular drain samples at 6 and 24 hours, to ascertain the systemic and local inflammatory responses. The Spearman's correlation was utilised to evaluate the relationship with PROMs and functional outcomes. Results. Reduced IL-6 drain fluid levels were noted at 6 hours [798.54 vs. 5699.2, p=0.026] and 24 hours and IL-8 at 6 hours. Patients in the robotic group had lower pain scores on post-operative day 1, 2 and 7. PROM scores were comparable at 2 years. Statistically significant correlations were evident between all serum markers except IL-1b on the 7th postoperative day and self-reported pain; between drain IL-8 levels and self-reported pain; between drain IL-6, IL-8 and TNF-a levels (6-hours) and knee flexion and extension. Conclusion. Robotic-arm assisted TKA was associated with a reduced postoperative local and systemic inflammatory responses. A moderate correlation with self-reported pain, knee flexion and extension was also demonstrated. Longer-term data and further validation on a larger scale, will be key to developing the optimal TKA procedure