The contralateral knee is a good predictor for determining normal knee stability: a cadaveric study.

PURPOSE: The goal is to evaluate contralateral knee joint laxity and ascertain whether or not contralateral symmetry is observable. Secondary, a validation of a knee laxity testing rig is provided. METHODS: Seven pairs of cadaveric knee specimens have been tested under passive conditions with and without external loads, involving a varus/valgus and an external/internal rotational torque and an anteroposterior shear force. RESULTS: Through the range of motion, the width of the varus/valgus laxity, internal/external laxity and anterior/posterior laxity for the medial and lateral compartment show no significant differences between left and right leg. These findings allow us to validate the setup, especially for relative values of laxity based on anatomical measures and knee joint biomechanics. CONCLUSION: A multidirectional laxity symmetry has been demonstrated for the intact knee and its contralateral knee in passive conditions as in an anesthetized patient. The passive laxity evaluation setup has been validated. Our work furthermore demonstrated a pronounced difference in anteroposterior mobility between the medial and lateral compartment of the knee, with a more stable medial side and more mobile lateral side. CLINICAL RELEVANCE: The contralateral knee can be used as reference for determining optimal knee laxity peri-operatively in total knee replacement and ligament reconstruction. LEVEL OF EVIDENCE: Level IV, Case series.

Higher satisfaction after total knee arthroplasty using restricted inverse kinematic alignment compared to adjusted mechanical alignment.

PURPOSE: Various alignment philosophies for total knee arthroplasty (TKA) have been described, all striving to achieve excellent long-term implant survival and good functional outcomes. In recent years, in search of higher functionality and patient satisfaction, a shift towards more tailored and patient-specific alignment is seen. The purpose of this study was to describe a restricted 'inverse kinematic alignment' (iKA) technique, and to compare clinical outcomes of patients that underwent robotic-assisted TKA performed by restricted iKA vs. adjusted mechanical alignment (aMA). METHODS: The authors reviewed the records of a consecutive series of patients that received robotic-assisted TKA with restricted iKA (n = 40) and with aMA (n = 40). Oxford Knee Score (OKS) and satisfaction on a visual analogue scale (VAS) were collected at a follow-up of 12 months. Clinical outcomes were assessed according to patient acceptable symptom state (PASS) thresholds, and uni- and multivariable linear regression analyses were performed to determine associations of OKS and satisfaction with six variables (age, sex, body mass index (BMI), preoperative hip-knee-ankle (HKA) angle, preoperative OKS, alignment technique). RESULTS: The restricted iKA and aMA techniques yielded comparable outcome scores (p = 0.069), with OKS, respectively, 44.6 ± 3.5 and 42.2 ± 6.3. VAS Satisfaction was better (p = 0.012) with restricted iKA (9.2 ± 0.8) compared to aMA (8.5 ± 1.3). The number of patients that achieved OKS and satisfaction PASS thresholds was significantly higher (p = 0.049 and p = 0.003, respectively) using restricted iKA (98% and 80%) compared to aMA (85% and 48%). Knees with preoperative varus deformity, achieved significantly (p = 0.025) better OKS using restricted iKA (45.4 ± 2.0) compared to aMA (41.4 ± 6.8). Multivariable analyses confirmed better OKS (ß = 3.1; p = 0.007) and satisfaction (ß = 0.73; p = 0.005) with restricted iKA. CONCLUSIONS: The results of this study suggest that restricted iKA and aMA grant comparable clinical outcomes at 12-month follow-up, though a greater proportion of knees operated by restricted iKA achieved the PASS thresholds for OKS and satisfaction. Notably. in knees with preoperative varus deformity, restricted iKA yielded significantly better OKS and satisfaction than aMA. LEVEL OF EVIDENCE: Level III, comparative study.

The ankle syndesmosis pivot shift "Are we reviving the ACL story?"

In recent literature, there is a growing interest for the high ankle sprain with emerging evidence on biomechanical behavior, function, injury, and treatment. Interpretation of emerging publications on the distal tibiofibular syndesmosis may raise questions about striking similarities with the anterior cruciate ligament function and pivot-shift mechanism of injury in the knee. This editorial note puts to question whether identical entities, a continuum or separate injuries are faced by contemplating on the mechanism of injury, diagnostics, treatment, and outcome.

Tunnel placement in ACL reconstruction surgery: smaller inter-tunnel angles and higher peak forces at the femoral tunnel using anteromedial portal femoral drilling-a 3D and finite element analysis.

PURPOSE: Recent studies have emphasized the importance of anatomical ACL reconstruction to restore normal knee kinematics and stability. Aim of this study is to evaluate and compare the ability of the anteromedial (AM) and transtibial (TT) techniques for ACL reconstruction to achieve anatomical placement of the femoral and tibial tunnel within the native ACL footprint and to determine forces within the graft during functional motion. As the AM technique is nowadays the technique of choice, the hypothesis is that there are significant differences in tunnel features, reaction forces and/or moments within the graft when compared to the TT technique. METHODS: Twenty ACL-deficient patients were allocated to reconstruction surgery with one of both techniques. Postoperatively, all patients underwent a computed tomography scan (CT) allowing 3D reconstruction to analyze tunnel geometry and tunnel placement within the native ACL footprint. A patient-specific finite element analysis (FEA) was conducted to determine reaction forces and moments within the graft during antero-posterior translation and pivot-shift motion. RESULTS: With significantly shorter femoral tunnels (p < 0.001) and a smaller inter-tunnel angle (p < 0.001), the AM technique places tunnels with less variance, close to the anatomical centre of the ACL footprints when compared to the TT technique. Using the latter, tibial tunnels were more medialised (p = 0.007) with a higher position of the femoral tunnels (p = 0.02). FEA showed the occurrence of higher, but non-significant, reaction forces in the graft, especially on the femoral side and lower, however, statistically not significant, reaction moments using the AM technique. CONCLUSION: This study indicates important, technique-dependent differences in tunnel features with changes in reaction forces and moments within the graft. LEVEL OF EVIDENCE: II.

Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis.

PURPOSE: To investigate the effect of tibial tunnel orientation on graft-bending angle and stress distribution in the ACL graft. METHODS: Eight cadaveric knees were scanned in extension, 45°, 90°, and full flexion. 3D reconstructions with anatomically placed anterior cruciate ligament (ACL) grafts were constructed with Mimics 14.12®. 3D graft-bending angles were measured for classic medial tibial tunnels (MTT) and lateral tibial tunnels (LTT) with different drill-guide angles (DGA) (45°, 55°, 65°, and 75°). A pivot shift was performed on 1 knee in a finite-element analysis. The peak stresses in the graft were calculated for eight different tibial tunnel orientations. RESULTS: In a classic anatomical ACL repair, the largest graft-bending angle and peak stresses are seen at the femoral tunnel aperture. The use of a different DGA at the tibial side does not change the graft-bending angle at the femoral side or magnitude of peak stresses significantly. When using LTT, the largest graft-bending angles and peak stresses are seen at the tibial tunnel aperture. CONCLUSION: In a classic anatomical ACL repair, peak stresses in the ACL graft are found at the femoral tunnel aperture. When an LTT is used, peak stresses are similar compared to classic ACL repairs, but the location of the peak stress will shift from the femoral tunnel aperture towards the tibial tunnel aperture. CLINICAL RELEVANCE: the risk of graft rupture is similar for both MTTs and LTTs, but the location of graft rupture changes from the femoral tunnel aperture towards the tibial tunnel aperture, respectively. LEVEL OF EVIDENCE: I.

Correction to: Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis.

Unfortunately, one of the co-author's name was missed in the original online publication of this article. The name should be included as sixth author in the author group.

The anterior cruciate ligament: a study on its bony and soft tissue anatomy using novel 3D CT technology.

PURPOSE: The purpose of this study is twofold: first, to visualize both the tibial and femoral bony insertion surfaces and second, to describe the anterior cruciate ligament (ACL) geometrically, using novel 3D CT imaging. In addition, new concepts of best-fit cylinder and central axis are introduced and evaluated. METHODS: Eight unpaired knees of embalmed cadavers were used in this study. Following the dissection process, the ACL was injected with a contrast medium for CT imaging. The obtained CT images in extension, 45°, 90° and full flexion were segmented and rendered in 3D allowing morphological and morphometric analysis of the ACL. Anatomical footprint centres, femoral and tibial footprint surface area, best-fit ACL-cylinder intersection area, best-fit ACL-cylinder/footprint coverage ratio, best-fit ACL-cylinder central axis projections at the tibial and femoral footprint in the four positions were used to describe the anatomy of the ACL, based on the Bernard, Hertel and Amis grid. RESULTS: Based on these parameters, with the best-fit cylinder representing the bulk of the ACL, a changing fibre-recruitment pattern was seen with a moving position of the central axis from posterior to anterior on the femoral and tibial footprint, going from extension to flexion. Furthermore, the numerical data show an increase in tibial footprint coverage by the best-fit cylinder through the ACL when the knee is progressively flexed, whereas an inverse relationship was seen on the femoral side. CONCLUSION: This study is the first to describe the detailed anatomy of the human ACL with respect to its course and footprints using a 3D approach. It confirms the large difference and inter-patient variability between the tibial and femoral footprint area with the former being significantly smaller. The best-fit cylinder concept illustrates the recruitment pattern of the native ACL where in extension the postero-lateral fibres are recruited and in flexion rather the antero-medial bundle, which can be valuable information in reconstructive purposes. The best-fit cylinder and central axis concept offers additional insights into the optimal tunnel placement at the tibial and femoral footprint in order to cover the largest portion of the native ACL soft tissue, aiming for optimal ACL reconstruction.

Does cruciate retention primary total knee arthroplasty affect proprioception, strength and clinical outcome?

PURPOSE: It remains unclear what the contribution of the PCL is in total knee arthroplasty (TKA). The goal of this study was to investigate the influence of the PCL in TKA in relationship to clinical outcome, strength and proprioception. METHODS: Two arthroplasty designs were compared: a posterior cruciate-substituting (PS) and a posterior cruciate-retaining (CR) TKA. A retrospective analysis was performed of 27 CR and 18 PS implants with a minimum of 1 year in vivo. Both groups were compared in terms of clinical outcome (range of motion, visual analogue scale for pain, Hospital for Special Surgery Knee Scoring system, Lysholm score and Knee Injury and Osteoarthritis Outcome Score), strength (Biodex System 3 Dynamometer(®)) and proprioception (balance and postural control using the Balance Master system(®)). Each design was also compared to the non-operated contralateral side in terms of strength and proprioception. RESULTS: There were no significant differences between both designs in terms of clinical outcome and strength. In terms of proprioception, only the rhythmic weight test at slow and moderate speed shifting from left to right was significant in favour of the CR design. None of the unilateral stance tests showed any significant difference between both designs. There was no difference in terms of strength and proprioception between the operated side and the non-operated side. CONCLUSION: Retaining the PCL in TKA does not result in an improved performance in terms of clinical outcome and proprioception and does not show any difference in muscle strength. LEVEL OF EVIDENCE: III.

Long-term follow-up of the anterior lumbar interbody fusion procedure.

PURPOSE: To evaluate the long-term clinical results and the effectiveness of the anterior lumbar interbody fusion procedure. METHODS: Between 1999 and 2005, 60 ALIFs were performed in 59 patients. Mean age was 41.1 years. Clinically, patients were evaluated at a mean follow-up of 9.5 years using the Visual Analogue Scale grading scale, the Oswestry Disability score and the SF-36 questionnaire. RESULTS: Preoperative and postoperative clinical evaluation scores of 38 patients were available. Nineteen patients were lost to follow-up, and 2 patients died during the follow-up. The fusion rate was 84%. Mean preoperative VAS-score for back pain was 6.69 (±2.15) ; in the long term, the mean VAS-score was 4.95 (±2.95), which was a significant improvement. (p<0.01). The postoperative ODI-score was 36.11 (±22.32), while the preoperative ODI-score was 59.31 (±17.16), which demonstrates a significant improvement. According to the SF-36, mild to good results were observed. CONCLUSIONS: The ALIF procedure can offer significant pain relief and improved function if a strict indication policy is followed.

Revision of meniscal transplants: long-term clinical follow-up.

PURPOSE: The primary aim is to document objective and subjective clinical outcome after knee arthroplasty for failed meniscal allograft transplantation; secondly, to investigate the influence of previous meniscal allograft surgery on the clinical outcome after a knee arthroplasty procedure; thirdly, to identify possible prognostic factors for the failure of meniscal allograft, such as potential number of concomitant procedures or pre-transplantation HSS-scores. The study population was compared to a control group of primary total knee arthroplasties. METHODS: The pre-operative phase, prior to meniscal allograft transplantation, was evaluated by the HSS questionnaire. At final follow-up, the clinical outcome was evaluated by the HSS, KOOS and SF-36 questionnaires. The mean follow-up was 16 years and 2 months. The control group, matched for age and sex, comprised patients with primary total knee arthroplasty. RESULTS: Statistical analysis showed that for the HSS-scores, there was no significant difference between the study population and the control group. KOOS data showed that the control group scored better overall. There was no significant difference between the HSS-scores after the transplantation and after the knee prosthesis. However, both showed a significant improvement regarding the clinical condition before meniscal transplantation. CONCLUSIONS: The clinical results after revised meniscal transplantation by means of knee prosthesis are highly variable with a tendency to have a lower score than patients with a primary knee prosthesis. Patients who underwent a revision of their meniscal allograft transplantation by means of a knee arthroplasty still had a significant better clinical outcome than prior to the meniscal allograft transplantation. There were no prognostic factors found by which one can determine whether a meniscal allograft will have a good survival or not.

The posterior cruciate ligament: a study on its bony and soft tissue anatomy using novel 3D CT technology.

PURPOSE: The bony insertion sites of the PCL have been studied and described extensively using 2D technology such as macroscopic images, plain radiograph, computerized tomography (CT) and MRI. The purpose of this study is to visualize both the tibial and the femoral bony insertion sites but also the soft tissue anatomy of the native PCL using novel 3D CT imaging. In addition, new concepts of best-fit cylinder and central axis are introduced and evaluated. METHODS: Nine unpaired knees of embalmed cadavers were used in this study. Following the dissection process, the PCL was injected with a contrast medium for computed tomography (CT) imaging. The obtained CT images were segmented and rendered in 3D allowing morphological and morphometric analysis of PCL. Femoral and tibial footprint surface area, best-fit PCL-cylinder intersection area, best-fit PCL-cylinder/footprint coverage ratio, best-fit PCL-cylinder central axis projections at the tibial and femoral footprint were used to describe the anatomy of the PCL. RESULTS: Mean footprint surface area of the tibial and femoral footprint were 189.1 and 293.3 mm², respectively. The mean diameter of the best-fit cylinder was 10.5 mm. The mean coverage of the best-fit cylinder on the tibial and femoral footprint was 76.5 and 46.5, respectively. The best-fit cylinder central axis was located in the anterolateral AL bundle footprint on the femur and more centrally in the PCL footprint on the tibia. CONCLUSION: This study is the first to describe the detailed anatomy of the human PCL with respect to its course and footprints using a 3D approach. It confirms the large difference between the tibial and the femoral footprint area with the former being significantly smaller. In addition, a large inter-patient variability is observed. The best-fit cylinder and central axis concept offer additional insights into the optimal tunnel placement at the tibia and femoral footprint in order to cover the largest portion of the native PCL soft tissue.

Intramedullary fixation of intertrochanteric hip fractures: a comparison of two implant designs. A prospective randomised clinical trial.

We report the results of a prospective randomized clinical trial comparing the Gamma 3 nail with the ACE trochanteric nail for the treatment of pertrochanteric femoral fractures. One hundred and twelve consecutive patients were enrolled in the study: 61 patients were treated with the Gamma 3 nail, 51 with the ACE trochanteric nail. The two groups were matched for age, fracture type and preoperative Merle d'Aubigné hip score. All patients were followed up clinically and radiographically on a regular basis between 6 weeks and one year postoperatively. Twenty-six patients (23%) died within the first postoperative year. Six patients were lost to follow-up. In each group, two patients were revised due to mechanical failure. Nonunion did not occur. The mean postoperative hip scores in the Gamma 3 and the ACE group were 14.19 and 14.12 respectively, with no significant difference (p = 0.92). Walking ability was adequately restored in approximately 80% of the patients. Both implants appeared as safe and effective methods of treatment for intertrochanteric hip fractures.

Inverse Kinematic Alignment for Total Knee Arthroplasty.

Patient specific alignment might improve clinical outcomes in total knee arthroplasty (TKA). Different alignment concepts are described, each providing specific features with theoretical benefits or possible disadvantages. Inverse kinematic alignment (iKA) is a new patient specific alignment concept with excellent reported clinical outcome and patient satisfaction at short-term follow-up. iKA is a tibia-first, gap balancing technique restoring the native tibial joint line obliquity (JLO). In each patient, within boundaries, equal medial and lateral tibial resections are performed, compensating for cartilage and bone loss. We describe the surgical technique of iKA using a robotic assisted system (Mako, Stryker, Kalamazoo, USA). A case series of 100 consecutive iKA cases is assessed and the bony resections and resection angles are reported. Both in the coronal plane and axial plane, iKA might offer advantages over existing alignment strategies, possibly providing optimal clinical outcome and durable long-term survival, regardless of the alignment is varus, neutral or valgus.

Prevention of venous thromboembolism with aspirin following knee surgery: A systematic review and meta-analysis.

Venous thromboembolism (VTE) is a well-known complication following orthopaedic surgery. The incidence of this complication has decreased substantially since the introduction of routine thromboprophylaxis. However, concerns have been raised about increased bleeding complications caused by aggressive thromboprophylaxis.Attention has grown for aspirin as a safer thromboprophylactic agent following orthopaedic surgery.A systematic review using MEDLINE, Embase and Web of Science databases was undertaken to compare the effectiveness of aspirin prophylaxis following knee surgery with the current standard prophylactic agents (low molecular weight heparin [LMWH], vitamin K antagonists and factor Xa inhibitors).No significant difference in effectiveness of VTE prevention was found between aspirin, LMWH and warfarin. Factor Xa inhibitors were more effective, but increased bleeding complications were reported.As evidence is limited and of low quality with substantial heterogeneity, further research with high-quality, adequately powered trials is needed. Cite this article: EFORT Open Rev 2021;6:892-904. DOI: 10.1302/2058-5241.6.200120.

Biceps Femoris Compensates for Semitendinosus After Anterior Cruciate Ligament Reconstruction With a Hamstring Autograft: A Muscle Functional Magnetic Resonance Imaging Study in Male Soccer Players.

BACKGROUND: Rates of reinjury, return to play (RTP) at the preinjury level, and hamstring strain injuries in male soccer players after anterior cruciate ligament reconstruction (ACLR) remain unsatisfactory, due to multifactorial causes. Recent insights on intramuscular hamstring coordination revealed the semitendinosus (ST) to be of crucial importance for hamstring functioning, especially during heavy eccentric hamstring loading. Scientific evidence on the consequences of ST tendon harvest for ACLR is scarce and inconsistent. This study intended to investigate the repercussions of ST harvest for ACLR on hamstring muscle function. HYPOTHESIS: Harvest of the ST tendon for ACLR was expected to have a significant influence on hamstring muscle activation patterns during eccentric exercises, evaluated at RTP in a population of male soccer athletes. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 30 male soccer players with a history of ACLR who were cleared for RTP and 30 healthy controls were allocated to this study during the 2018-2019 soccer season. The influence of ACLR on hamstring muscle activation patterns was assessed by comparing the change in T2 relaxation times [ΔT2 (%) = post-exercise-T2pre-exerciseT2pre-exercise] of the hamstring muscle tissue before and after an eccentric hamstring loading task between athletes with and without a recent history of ACLR through use of muscle functional magnetic resonance imaging, induced by an eccentric hamstring loading task between scans. RESULTS: Significantly higher exercise-related activity was observed in the biceps femoris (BF) of athletes after ACLR compared with uninjured control athletes (13.92% vs 8.48%; P = .003), whereas the ST had significantly lower activity (19.97% vs 25.32%; P = .049). Significant differences were also established in a within-group comparison of the operated versus the contralateral leg in the ACLR group (operated vs nonoperated leg: 14.54% vs 11.63% for BF [P = .000], 17.31% vs 22.37% for ST [P = .000], and 15.64% vs 13.54% for semimembranosus [SM] [P = .014]). Neither the muscle activity of SM and gracilis muscles nor total posterior thigh muscle activity (sum of exercise-related ΔT2 of the BF, ST, and SM muscles) presented any differences in individuals who had undergone ACLR with an ST tendon autograft compared with healthy controls. CONCLUSION: These findings indicate that ACLR with a ST tendon autograft might notably influence the function of the hamstring muscles and, in particular, their hierarchic dimensions under fatiguing loading circumstances, with increases in relative BF activity contribution and decreases in relative ST activity after ACLR. This between-group difference in hamstring muscle activation pattern suggests that the BF partly compensates for deficient ST function in eccentric loading. These alterations might have implications for athletic performance and injury risk and should probably be considered in rehabilitation and hamstring injury prevention after ACLR with a ST tendon autograft.

Knee arthroplasty for acute fractures around the knee.

Results of open reduction and internal fixation for complex articular fractures around the knee are poor, particularly in elderly osteoporotic patients.Open reduction and internal fixation may lead to an extended hospital stay and non-weight-bearing period.This may lead to occurrence of complications related to decubitus such as thrombo-embolic events, pneumonia and disorientation.Primary arthroplasty can be a valuable option in a case-based and patient-specific approach. It may reduce the number of procedures and allow early full weight-bearing, avoiding the above-mentioned complications.There are four main indications: 1) Elderly (osteoporotic) patients with pre-existing (symptomatic) end-stage osteoarthritis.2) Elderly (osteoporotic) patients with severe articular and metaphyseal destruction.3) Pathological fractures of the distal femur and/or tibia.4) Young patients with complete destruction of the distal femur and/or tibia.The principles of knee (revision) arthroplasty should be applied; choice of implant and level of constraint should be considered depending on the type of fracture and involvement of stabilizing ligaments. The aim of treatment is to obtain a stable and functional joint.Long-term data remain scarce in the literature due to limited indications. Cite this article: EFORT Open Rev 2020;5:713-723. DOI: 10.1302/2058-5241.5.190059.

How should we evaluate robotics in the operating theatre?

The application of robotics in the operating theatre for knee arthroplasty remains controversial. As with all new technology, the introduction of new systems might be associated with a learning curve. However, guidelines on how to assess the introduction of robotics in the operating theatre are lacking. This systematic review aims to evaluate the current evidence on the learning curve of robot-assisted knee arthroplasty. An extensive literature search of PubMed, Medline, Embase, Web of Science, and Cochrane Library was conducted. Randomized controlled trials, comparative studies, and cohort studies were included. Outcomes assessed included: time required for surgery, stress levels of the surgical team, complications in regard to surgical experience level or time needed for surgery, size prediction of preoperative templating, and alignment according to the number of knee arthroplasties performed. A total of 11 studies met the inclusion criteria. Most were of medium to low quality. The operating time of robot-assisted total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) is associated with a learning curve of between six to 20 cases and six to 36 cases respectively. Surgical team stress levels show a learning curve of seven cases in TKA and six cases for UKA. Experience with the robotic systems did not influence implant positioning, preoperative planning, and postoperative complications. Robot-assisted TKA and UKA is associated with a learning curve regarding operating time and surgical team stress levels. Future evaluation of robotics in the operating theatre should include detailed measurement of the various aspects of the total operating time, including total robotic time and time needed for preoperative planning. The prior experience of the surgical team should also be evaluated and reported. Cite this article: Bone Joint J 2020;102-B(4):407-413.