Anterior cruciate ligament injury and age affect knee cartilage T2 but not thickness.

OBJECTIVE: To investigate the effect of unilateral anterior cruciate ligament (ACL) injury on cartilage thickness and composition, specifically laminar transverse relaxation time (T2) by magnetic resonance imaging (MRI), in younger and older participants and to compare within-person side differences in these parameters between ACL-injured and healthy controls. DESIGN: Quantitative double-echo steady-state 3 Tesla MRI-sequences were acquired in both knees of 85 participants in four groups: 20-30 years: healthy, HEA20-30, n = 24; ACL-injured, ACL20-30, n = 23; 40-60 years: healthy, HEA40-60, n = 24; ACL-injured, ACL40-60, n = 14 (ACL injury 2-10 years prior to study inclusion). Weight-bearing femorotibial cartilages were manually segmented; cartilage T2 and thickness were computed using custom software. Mean and side differences in subregional cartilage thickness, superficial and deep cartilage T2 were compared within and between groups using non-parametric statistics. RESULTS: Cartilage thickness did not differ within or between groups. Only the side difference in medial femorotibial cartilage thickness was greater in ACL20-30 than in HEA20-30. Deep zone T2 was longer in the ACL-injured than in the contralateral uninjured knees and than in healthy controls, especially in the lateral compartment. Most ACL-injured participants had side differences in femorotibial deep zone T2 above the threshold derived from controls. CONCLUSION: In the ACL-injured knee, early compositional differences in femorotibial cartilage (T2) appear to occur in the deep zone and precede cartilage thickness loss. These results suggest that monitoring laminar T2 after ACL injury may be useful in diagnosing and monitoring early articular cartilage changes.

Ambulatory knee biomechanics and muscle activity 2 years after ACL surgery: InternalBraceTM-augmented ACL repair versus ACL reconstruction versus healthy controls.

BACKGROUND: Little is known about knee mechanics and muscle control after augmented ACL repair. Our aim was to compare knee biomechanics and leg muscle activity during walking between the legs of patients 2 years after InternalBraceTM-augmented anterior cruciate ligament repair (ACL-IB) and between patients after ACL-IB and ACL reconstruction (ACL-R), and controls. METHODS: Twenty-nine ACL-IB, 27 sex- and age-matched ACL-R (hamstring tendon autograft) and 29 matched controls completed an instrumented gait analysis. Knee joint angles, moments, power, and leg muscle activity were compared between the involved and uninvolved leg in ACL-IB (paired t-tests), and between the involved legs in ACL patients and the non-dominant leg in controls (analysis of variance and posthoc Bonferroni tests) using statistical parametric mapping (SPM, P < 0.05). Means and 95% confidence intervals (CI) of differences in discrete parameters (DP; i.e., maximum/minimum) were calculated. RESULTS: Significant differences were observed in ACL-IB only in minimum knee flexion angle (DP: 2.4°, CI [-4.4;-0.5]; involved > uninvolved) and maximum knee flexion moment during stance (-0.07Nm/kg, CI [-0.13;-0.00]; involved < uninvolved), and differences between ACL-IB and ACL-R only in maximum knee flexion during swing (DP: 3.6°, CI [0.5;7.0]; ACL-IB > ACL-R). Compared to controls, ACL-IB (SPM: 0-3%GC, P = 0.015; 98-100%, P = 0.016; DP: -6.3 mm, CI [-11.7;-0.8]) and ACL-R (DP: -6.0 mm, CI [-11.4;-0.2]) had lower (maximum) anterior tibia position around heel strike. ACL-R also had lower maximum knee extension moment (DP: -0.13Nm/kg, CI [-0.23;-0.02]) and internal knee rotation moment (SPM: 34-41%GC, P < 0.001; DP: -0.03Nm/kg, CI [-0.06;-0.00]) during stance, and greater maximum semitendinosus activity before heel strike (DP: 11.2%maximum voluntary contraction, CI [0.1;21.3]) than controls. CONCLUSION: Our results suggest comparable ambulatory knee function 2 years after ACL-IB and ACL-R, with ACL-IB showing only small differences between legs. However, the differences between both ACL groups and controls suggest that function in the involved leg is not fully recovered and that ACL tear is not only a mechanical disruption but also affects the sensorimotor integrity, which may not be restored after surgery. The trend toward fewer abnormalities in knee moments and semitendinosus muscle function during walking after ACL-IB warrants further investigation and may underscore the importance of preserving the hamstring muscles as ACL agonists. LEVEL OF EVIDENCE: Level III, case-control study. TRIAL REGISTRATION: clinicaltrials.gov, NCT04429165 (12/06/2020).

Distal femoral osteotomy for the valgus knee: indications, complications, clinical and radiological outcome.

INTRODUCTION: The aim of this study was to describe the indications and technical aspects of medial closing and lateral opening distal femoral osteotomy (MCDFO and LODFO) for patients with a valgus knee and to report clinical and radiological outcomes and complications. METHODS: Over 6 years, 28 DFOs (22 MCDFO, 6 LODFO) were performed in 22 Patients. In this cohort study, we retrospectively analyzed clinical and radiological outcome measures as well as complications. RESULTS: The median (range) age was 47 (17-63) years, height 1.68 (1.56-1.98) m, body mass 80 (49-105) kg, and body mass index (BMI) 27.4 (18.6-37.0) kg/m2. The clinical follow-up was 21 (7-81) months, the need for total or unicompartmental knee arthroplasty (TKA/UKA) and hardware removal was followed up for 59 (7-108) months postoperatively. Preoperatively, hip-knee-ankle angle (HKA, negative values denote varus) was 7.0 (2.0-13.0)°, mechanical lateral distal femoral angle (mLDFA) was 83.7 (79.9-88.2)°, and mechanical proximal tibial angle (MPTA) was 89.0 (86.6-94.5)°. Postoperatively, HKA was -1.3 (-9.0-1.2)° and mLDFA was 90.8 (87.3-97.3)°. The incidence of minor and major complications was 25% and 14%, the incidence of delayed and nonunion was 18% and 4%, respectively. At the last follow-up, 18% of the patients had pain at rest, 25% during activities of daily living, and 39% during physical activity, and 71% were satisfied with the outcome. 7% of the cases received a TKA/UKA, 71% received a hardware removal. CONCLUSION: DFO is a reasonable treatment for lateral osteoarthritis in younger patients to avoid disease progression and the need for an UKA/TKA. However, there is a long rehabilitation time, a considerable risk for complications, and a high need for hardware removal. While many patients experienced symptoms at the long-term follow-up, most were satisfied with the outcome. Appropriate patient information is essential. Level of evidence Level IV, Case Series. Trial registration number NCT04382118, clinicaltrials.gov, May 11, 2020.

Functional leg performance 2 years after ACL surgery: a comparison between InternalBrace™-augmented repair versus reconstruction versus healthy controls.

BACKGROUND: While clinical and patient-reported outcomes have been investigated in patients after InternalBrace™-augmented anterior cruciate ligament repair (ACL-IB), less is known regarding restoration of functional performance. We aimed to determine differences in functional performance within and between patients 2 years after ACL-IB, patients 2 years after ACL reconstruction (ACL-R), and healthy controls. MATERIALS AND METHODS: A total of 29 ACL-IB, 27 ACL-R (hamstring autograft), and 29 controls performed single-leg hop (maximum forward distance hop, SLH; side hop > 40 cm in 30 s, SH), proprioception (knee joint position sense at 30° and 60° flexion), and dynamic postural balance (Y Balance) tests. Differences were calculated within groups (side-to-side difference) and between the involved leg of patients and the non-dominant leg of controls, and were evaluated to predefined statistical (P < 0.05), clinically relevant, and methodological (smallest detectable change) thresholds. The number of exceeded thresholds represented no (0), small (1), moderate (2), or strong (3) differences. In addition, the relative number of participants achieving leg symmetry (≥ 90%) and normal performance (≥ 90% of the average performance of the non-dominant leg of controls) were compared between groups (chi-squared tests, P < 0.05). RESULTS: We observed no-to-moderate leg differences within ACL-IB (moderate difference in hops) and within ACL-R (moderate difference in knee proprioception), no leg differences between patient groups, no-to-small leg differences between ACL-IB and controls, and no leg differences between ACL-R and controls in functional performance. However, two patients in ACL-IB and ACL-R, respectively, passed the hop pretest only with their uninvolved leg, and fewer patients after ACL-IB and ACL-R than controls reached a leg symmetry and normal leg performance of controls in SLH (P < 0.001). CONCLUSIONS: Functional performance seems to be comparable 2 years postoperatively between ACL-IB and ACL-R for a specific subgroup of patients (i.e., proximal ACL tears, moderate activity level). However, the presumed advantage of comparable functional outcome with preserved knee structures after augmented ACL repair compared with ACL-R, and the tendency of both patient groups toward leg asymmetry and compromised single-leg hop performance in the involved legs, warrants further investigation. Level of Evidence Level III, case-control study. Trial registration clinicaltrials.gov, NCT04429165 (12/09/2020). Prospectively registered, https://clinicaltrials.gov/ct2/show/NCT04429165 .

In Vitro and Ectopic In Vivo Studies toward the Utilization of Rapidly Isolated Human Nasal Chondrocytes for Single-Stage Arthroscopic Cartilage Regeneration Therapy.

Nasal chondrocytes (NCs) have a higher and more reproducible chondrogenic capacity than articular chondrocytes, and the engineered cartilage tissue they generate in vitro has been demonstrated to be safe in clinical applications. Here, we aimed at determining the feasibility for a single-stage application of NCs for cartilage regeneration under minimally invasive settings. In particular, we assessed whether NCs isolated using a short collagenase digestion protocol retain their potential to proliferate and chondro-differentiate within an injectable, swiftly cross-linked and matrix-metalloproteinase (MMP)-degradable polyethylene glycol (PEG) gel enriched with human platelet lysate (hPL). NC-hPL-PEG gels were additionally tested for their capacity to generate cartilage tissue in vivo and to integrate into cartilage/bone compartments of human osteochondral plugs upon ectopic subcutaneous implantation into nude mice. NCs isolated with a rapid protocol and embedded in PEG gels with hPL at low cell density were capable of efficiently proliferating and of generating tissue rich in glycosaminoglycans and collagen II. NC-hPL-PEG gels developed into hyaline-like cartilage tissues upon ectopic in vivo implantation and integrated with surrounding native cartilage and bone tissues. The delivery of NCs in PEG gels containing hPL is a feasible strategy for cartilage repair and now requires further validation in orthotopic in vivo models.

Assessing Site Specificity of Osteoarthritic Gait Kinematics with Wearable Sensors and Their Association with Patient Reported Outcome Measures (PROMs): Knee versus Hip Osteoarthritis.

There is a great need for quantitative outcomes reflecting the functional status in patients with knee or hip osteoarthritis (OA) to advance the development and investigation of interventions for OA. The purpose of this study was to determine if gait kinematics specific to the disease-i.e., knee versus hip OA-can be identified using wearable sensors and statistical parametric mapping (SPM) and whether disease-related gait deviations are associated with patient reported outcome measures. 113 participants (N = 29 unilateral knee OA; N = 30 unilateral hip OA; N = 54 age-matched asymptomatic persons) completed gait analysis with wearable sensors and the Knee/Hip Osteoarthritis Outcome Score (KOOS/HOOS). Data were analyzed using SPM. Knee and hip kinematics differed between patients with knee OA and patients with hip OA (up to 14°, p < 0.001 for knee and 8°, p = 0.003 for hip kinematics), and differences from controls were more pronounced in the affected than unaffected leg of patients. The observed deviations in ankle, knee and hip kinematic trajectories from controls were associated with KOOS/HOOS in both groups. Capturing gait kinematics using wearables has a large potential for application as outcome in clinical trials and for monitoring treatment success in patients with knee or hip OA and in large cohorts representing a major advancement in research on musculoskeletal diseases.

Lateral trochlear lengthening osteotomy.

INTRODUCTION: The purpose of this study was to describe the indications and technical aspects as well as evaluate the clinical and functional outcome of lengthening osteotomy of the lateral trochlear ridge in patients with patellofemoral pain and/or patella instability and presence of trochlear dysplasia Dejour type A or lack of Dejour type dysplasia and short lateral articular trochlea. MATERIALS AND METHODS: Six consecutive adult patients were treated with a lateral trochlear lengthening osteotomy. Five patients received a concomitant medial patellofemoral ligament reconstruction. Three patients had prior patella stabilization surgeries. Trochlea dysplasia (Dejour classification), Caton-Dechamps index, tibial tubercle trochlear groove (TT-TG) distance, patellar tilt and lateral condylar index were measured in preoperative MRIs. Clinical and functional evaluation included the Kujala Anterior Knee Pain Scale, the Lysholm Knee Score, the Tegner Activity Score, a subjective evaluation form and isokinetic muscle strength. RESULTS: Four patients had a Dejour type A dysplasia, two patients had no dysplasia. The mean (range) Caton-Dechamps index was 1.09 (0.95-1.16), TT-TG distance 10.9 mm (9.2-15.6 mm), patellar tilt 15° (4-32°) and lateral condylar index 82.0% (74-90%). One patient was lost to follow up, all others were followed for 2-5 years. All patients were satisfied with the clinical outcome. The Lysholm score increased from 55 (37-79) to 89 (76-100), the Tegner activity score from 3.6 (2-6) to 5.6 (5-7). The Kujala score postoperative was 90 (75-96). Some but not all patients had full strength recovery compared to the contralateral leg. CONCLUSION: We recommend measuring the lateral condylar index and considering the indication of a lateral trochlear lengthening osteotomy as an additional or isolated procedure in selected patients with trochlear dysplasia Dejour type A or lack of dysplasia and short lateral articular trochlea depending on the extent of the patellar instability. LEVEL OF EVIDENCE: Level IV, Case Series. TRIAL REGISTRATION NUMBER: NCT04378491, clinicaltrials.gov, May 7, 2020.

[Total knee arthroplasty in the young patient-an update]. / Bikondylärer Oberflächenersatz des Kniegelenkes beim jungen Patienten ­ ein Update.

The absolute number of total knee arthroplasties (TKA) continues to rise every year. About 10% of the patients are less than 55 years of age, although it is known that functional results and patient satisfaction are lower combined with an increased likelihood of revision compared to older patients. Higher physical activity and patient expectations are a major challenge in this age group. At the same time, the incidence of posttraumatic/postoperative alterations is high, including ligamentous or bony deficiencies, which can make the surgical procedure challenging. In view of these facts conservative treatments and joint sparing procedures should always be considered first. The potential correction of lower-limb deformities and unicompartmental knee arthroplasties need to be carefully evaluated before considering total knee arthroplasty. Only in advanced cases of osteoarthritis in more than one compartment of the knee of with combined ligamentous instability, can a TKA provide satisfactory results in the young patient. However, the strongest predictor of satisfaction is a realistic expectation.

Good vibrations: Itch induction by whole body vibration exercise without the need of a pruritogen.

Mechanically induced itch is an important cofactor in many patients with chronic itch. However, studying mechanical itch in a controlled environment is challenging because it is difficult to evoke. We investigated the use of whole body vibration (WBV) exercise, a training method used for musculoskeletal rehabilitation, to experimentally evoke mechanical itch. Mild to severe itch ascending from the soles to the groins was evoked in 16 of 20 healthy participants. We observed a characteristic on/off itch crescendo pattern reflecting the alternating intervals of vibration and no vibration. Wheals or an angioedema was absent, and serum mast cell tryptase was not increased by the exercise. Participants described the evoked sensation primarily as "itching" with some nociceptive components. Itch intensity correlated with the intensity of a concomitant erythema (R = 0.45, P = 0.043) and with the rise in skin temperature (R = 0.54, P = 0.017). Hence, WBV can be used as an easily applicable, noninvasive, investigator- and user-friendly framework for studying mechanical itch. Moreover, WBV allows to "switch itch on and off" rapidly and to simultaneously study interactions between itch, skin blood flow and skin temperature.

Correction to: No added value using SPECT/CT to analyze persistent symptoms after anterior cruciate ligament reconstruction.

The shared first authorship of Christian Egloff, MD and Lukas Huber was always planned and correctly acknowledged.

No added value using SPECT/CT to analyze persistent symptoms after anterior cruciate ligament reconstruction.

PURPOSE: To evaluate the diagnostic and clinical value of SPECT/CT compared to the standard algorithm for patients with persistent symptoms after anterior cruciate ligament reconstructions. The standard algorithm uses clinical information, conventional radiographs, MRI and CT scan, while the trial algorithm uses the same information but SPECT/CT in addition. METHODS: In a diagnostic comparative trial three experienced surgeons evaluated 23 consecutive patients with persistent symptoms after ACL reconstruction using first standard and second the trial algorithm with a time interval. Each rater had to establish a diagnosis and therapeutic decision with each algorithm. On MRI, graft continuity, bone marrow edema, chondral and meniscal lesions, femoral notch osteophytes were evaluated. Bone tracer uptake in SPECT/CT was anatomically analyzed and compared with MRI findings. MRI findings and SPECT/CT tracer uptake were correlated using Spearman's rho test. RESULTS: Additional SPECT/CT analysis did not change diagnosis in any case and did not correlate with clinical graft integrity. Treatment decisions remained unchanged as well. Chondral lesions, arthritic changes, meniscal lesions, graft impingement are best visualized in MRI and showed correspondent tracer uptake in SPECT/CT. Tunnel position was well classified with standard CT scan and showed no correlation with SPECT/CT tracer uptake. CONCLUSION: Information derived by SPECT/CT in addition to the standard algorithm using clinical information, X-rays, MRI, and CT scan did not change the diagnosis or treatment plan. There is currently no justification to implement SPECT/CT for patients with persistent symptoms after anterior cruciate ligament reconstructions. LEVEL OF EVIDENCE: Level II: diagnostic comparative study.

Does patella alta lead to worse clinical outcome in patients who undergo isolated medial patellofemoral ligament reconstruction? A systematic review.

INTRODUCTION: The aim of this systematic review is to determine the effect of patella height on clinical outcomes after isolated MPFL reconstruction for patella instability. Our primary hypothesis is that patients with patella alta report similar outcomes after isolated MPFL reconstruction compared to patients with normal patella height. METHODS: A review of the literature was performed according to the PRISMA guidelines. PubMed, EMBASE, and the Cochrane Library were searched from inception to January 10th 2018. Studies were identified using synonyms for "medial patellofemoral ligament", "reconstruction" and "patella alta". RESULTS: The search resulted in 467 reports on PubMed, 175 on EMBASE and 3 on the Cochrane Library. We included and analyzed in detail six studies describing outcomes after isolated medial patellofemoral ligament reconstruction with regard to patellar height. We found that both patients with patella alta and normal patella height reported satisfactory outcomes after isolated medial patellofemoral ligament reconstruction. However, because of applied exclusion criteria in the included studies the total number of patients with severe patella alta was small (13/74 patients with patella alta, 18%). CONCLUSIONS: Based on the current literature we suggest that additional tibial tubercle distalisation is not mandatory in patients with mild patella alta (Caton-Deschamps Index 1.2-1.4). To assess the best indications for different surgical procedures for patients with patella instability future research is needed to develop a clear and uniform definition of relevant patella alta. LEVEL OF EVIDENCE: III.

Reduction Osteotomy of the Prominent Tibial Tubercle After Osgood-Schlatter Disease.

PURPOSE: To evaluate the functional and clinical outcome of a new closing-wedge osteotomy for the prominent tibial tubercle after Osgood-Schlatter disease. METHODS: Between 2010 and 2014, 7 consecutive adults (mean age, 28.6 years; range, 26-35 years) were treated by closing-wedge reduction osteotomy of a painful tibial tubercle. All patients had prior nonsurgical and surgical treatment. Preoperative and postoperative tubercular prominence, Caton-Deschamps index for patellar height, the Kujala Anterior Knee Pain Scale, Lysholm Knee Score as well as visual analog scale score and Tegner activity scores were recorded. RESULTS: Mean follow-up after reduction osteotomy was 31.3 months (27-41 months). The bony prominence of the tibial tubercle was significantly reduced (mean 8 mm, P < .001) and the Caton-Deschamps index was lowered from 1.29 to 1.09 (P < .001). From preoperative to last follow-up, the Kujala Anterior Knee Pain Scale increased from 54.71 preoperative to 84.71 (P < .001); the Lysholm Knee Score improved from 72.42 to 94.14 (P < .001); the Tegner activity score increased from 3.1 to 5.7 (P < .001), whereas the visual analog scale significantly decreased from 5.8 to 1.2 (P < .001). No complications were recorded, and all patients were satisfied with clinical outcome. CONCLUSIONS: Closing-wedge osteotomy of the tibial tubercle effectively reduced the bony prominence after Osgood-Schlatter disease and consecutively improved the outcome in terms of knee pain and function. Thus, we can recommend this procedure in selected patients. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Classification of inertial sensor-based gait patterns of orthopaedic conditions using machine learning: A pilot study.

Elderly patients often have more than one disease that affects walking behavior. An objective tool to identify which disease is the main cause of functional limitations may aid clinical decision making. Therefore, we investigated whether gait patterns could be used to identify degenerative diseases using machine learning. Data were extracted from a clinical database that included sagittal joint angles and spatiotemporal parameters measured using seven inertial sensors, and anthropometric data of patients with unilateral knee or hip osteoarthritis, lumbar or cervical spinal stenosis, and healthy controls. Various classification models were explored using the MATLAB Classification Learner app, and the optimizable Support Vector Machine was chosen as the best performing model. The accuracy of discrimination between healthy and pathologic gait was 82.3%, indicating that it is possible to distinguish pathological from healthy gait. The accuracy of discrimination between the different degenerative diseases was 51.4%, indicating the similarities in gait patterns between diseases need to be further explored. Overall, the differences between pathologic and healthy gait are distinct enough to classify using a classical machine learning model; however, routinely recorded gait characteristics and anthropometric data are not sufficient for successful discrimination of the degenerative diseases.

Favorable Patient-Reported, Clinical, and Functional Outcomes 2 Years After ACL Repair and InternalBrace Augmentation Compared With ACL Reconstruction and Healthy Controls.

BACKGROUND: Recently, interest in anterior cruciate ligament (ACL) preservation and repair after proximal ACL tears has been resurrected. Although good clinical outcomes have been reported in the literature with adequate patient selection, to date detailed scientific evidence for the functional benefit of primary ACL repair with ligament augmentation is scarce. PURPOSE: To compare patient-reported, clinical, and functional outcomes in patients 2 years after ACL repair and InternalBrace augmentation (ACL-IB) with age- and sex-matched patients 2 years after ACL reconstruction (ACL-R) and with matched healthy controls. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: In total, 29 patients 2 years after ACL-IB, 27 sex- and age- matched patients 2 years after ACL-R (hamstring autografts), and 29 matched healthy controls were included. Patient-reported outcomes were assessed using the International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, EQ-5D-5L, Tegner Activity Scale, and Anterior Cruciate Ligament Return to Sports after Injury scale. Surgery time was recorded. For clinical outcomes, range of motion and thigh and shank circumference were measured, and passive anterior translation was determined using the Rolimeter. Isokinetic muscle strength was measured using a Biodex dynamometer. The limb symmetry index (operated/contralateral or nondominant/dominant × 100), side-to-side differences (operated - contralateral, nondominant - dominant), and hamstring-quadriceps ratios were calculated for functional parameters. Failure and reoperation rates were not compared. RESULTS: Two years after surgery, patients treated with ACL-IB showed good to excellent patient-reported outcomes comparable with those of patients after ACL-R. Surgery time, including concomitant surgeries, was significantly shorter in the ACL-IB group (mean, 81 minutes) compared with the ACL-R group (mean, 97 minutes) (P = .024). Isokinetic muscle strength was comparable between patient groups without significant differences in extensor and flexor strength or in hamstring-quadriceps ratios. CONCLUSION: These results suggest that ACL-IB achieves comparable patient-reported, clinical, and functional outcomes with ACL-R at 2 years postoperatively and, after careful patient selection, should be considered as a valuable early treatment alternative for proximal ACL tears. REGISTRATION: NCT04429165 (ClinicalTrials.gov identifier).

High tibial osteotomy effectively redistributes compressive knee loads during walking.

The objectives of this study were to estimate pre- and postoperative lower limb kinematics and kinetics and knee intra-articular forces during gait using musculoskeletal modeling in a cohort of patients with knee osteoarthritis (OA) undergoing high tibial osteotomy (HTO), compare these to controls, and determine correlations between changes in these parameters and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores after HTO. Sixteen patients with isolated, symptomatic medial compartment knee OA completed pre- and postoperative gait analysis (mean follow-up time: 8.6 months). Sixteen age- and sex-matched asymptomatic volunteers participated as controls. Musculoskeletal modeling was used to evaluate lower limb joint moments and knee contact forces during gait. While HTO had limited influence on sagittal plane kinematics and moments, significant changes in the load distribution at the knee after HTO were observed with a lower postoperative compressive load on the medial compartment during midstance and a higher compressive load on the lateral compartment during early and late stance. Moreover, the lateral shear force in midstance was significantly lower after HTO. Changes in the external knee adduction moment (KAM) did not always coincide with reductions in the knee compressive force in the medial compartment. Biomechanical changes did not correlate with improvements in KOOS subscores. Hence, HTO effectively unloaded the medial compartment by redistributing part of the overall compressive force to the lateral compartment during gait with limited influence on gait function. The KAM may not adequately describe compartmental load magnitude or changes induced by interventions at the compartment level. Clinical trial registration: ClinicalTrials. gov Identifier-NCT02622204. Clinical significance: This study provides important evidence for changes in joint level loads after corrective osteotomy as joint preserving surgery and emphasizes the need for additional biomechanical outcomes of such interventions.

Effect of load carriage on joint kinematics, vertical ground reaction force and muscle activity: Treadmill versus overground walking.

BACKGROUND: Previous studies have investigated the effect of either different load or different surface conditions, such as overground or treadmill walking, on human biomechanics. However, studies combining these two aspects are scarce. RESEARCH QUESTION: The purpose of this study was to quantify the difference in spatiotemporal parameters, lower extremity joint kinematics, vertical ground reaction forces (vGRF) and muscle activity between normal bodyweight (100 %BW) and 20 % increased bodyweight (120 %BW) during overground and treadmill walking. METHODS: Ten healthy young adults walked overground at self-selected speed and on an instrumented treadmill set to the overground speed. Spatiotemporal parameters, 3-dimensional lower extremity kinematics, vGRF and muscle activity were measured and compared between conditions. RESULTS: The stance phase was longer for 120 %BW than 100 %BW in both overground and treadmill walking. Further, the stance phase was longer and cadence higher in treadmill than overground walking for both load conditions. Knee flexion angles were more than 3° greater in the second half of swing in treadmill than in overground walking. The vGRF was higher for 120 %BW compared to 100 %BW on both surfaces (treadmill, first peak: +18.6 %BW; second peak: +13.5 %BW; overground, first peak: +22.2 %BW; second peak: +19.8 %BW). Differences between conditions greater than 20 % were observed in short periods during the gait cycle for vastus medialis, vastus lateralis and semitendinosus. SIGNIFICANCE: Results regarding the effects of carrying additional load using a weight vest on joint kinematics during treadmill walking may be translated to overground walking but some changes in muscle activation can be expected.

Load-induced blood marker kinetics in patients with medial knee compartment osteoarthritis are associated with accumulated load and patient reported outcome measures.

Background: This study aimed to quantify the mechanoresponse of 10 blood marker candidates for joint metabolism to a walking stress test in patients with knee osteoarthritis and to determine the association among marker kinetics and with accumulated load and patient reported outcomes. Methods: 24 patients with knee osteoarthritis completed questionnaires, and a 30-minute walking stress test with six blood serum samples and gait analysis. Concentrations of cartilage oligomeric matrix protein (COMP), matrix metalloproteinases (MMP)-1, -3, and -9, epitope resulting from cleavage of type II collagen by collagenases (C2C), type II procollagen (CPII), interleukin (IL)-6, proteoglycan (PRG)-4, A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4, and resistin were determined by enzyme-linked immunosorbent assays, Joint load (moments and compartmental forces) was estimated using musculoskeletal modeling using gait analysis data. Results: COMP and MMP-3 showed an immediate increase after the walking stress followed by a decrease. MMP-9 and resistin showed a delayed decrease below pre-stress levels. ∆COMP correlated with ∆MMP-3 for most time points. ∆MMP-9 correlated with ∆resistin for most time points. The load-induced increase in blood marker levels correlated among blood markers and time points. C2C and resistin correlated positively and C2C/CPII and MMP2 correlated negatively with load during gait. Immediate relative ∆CPII and ∆MMP1 and delayed relative ∆COMP, ∆IL6, ∆C2C, ∆CPII, ∆MMP1 and ∆MMP3 correlated with the load accumulated during the walking stress. Baseline C2C levels correlated with Knee Osteoarthritis Outcome Score (KOOS) subscales and load-induced changes in MMP-3 with KOOS and Short Form 36 quality of life subscores (P<0.05). Conclusions: The distinct and differentiated physiological response to the walking stress depends on accumulated load and appears relevant for patient reported osteoarthritis outcome and quality of life and warrants further investigation in the context of disease progression.ClinicalTrials.gov registration: NCT02622204.

A Novel Sensor-Based Application for Home-Based Rehabilitation Can Objectively Measure Postoperative Outcomes following Anterior Cruciate Ligament Reconstruction.

In order to successfully implement individualized patient rehabilitation and home-based rehabilitation programs, the rehabilitation process should be objectifiable, monitorable and comprehensible. For this purpose, objective measurements are required in addition to subjective measurement tools. Thus, the aim of this prospective, single-center clinical trial is the clinical validation of an objective, digital medical device (DMD) during the rehabilitation after anterior cruciate ligament reconstruction (ACLR) with regards to an internationally accepted measurement tool. Sixty-seven patients planned for primary ACLR (70:30% male-female, aged 25 years [21-32], IKDC-SKF 47 [31-60], Tegner Activity Scale 6 [4-7], Lysholm Score 57 [42-72]) were included and received physical therapy and the DMD after surgery. For clinical validation, combined measures of range of motion (ROM), coordination, strength and agility were assessed using the DMD in addition to patient-reported outcome measures (PROMs) at three and six months after ACLR. Significant correlations were detected for ROM (rs = 0.36-0.46, p < 0.025) and strength/agility via the single-leg vertical jump (rs = 0.43, p = 0.011) and side hop test (rs = 0.37, p = 0.042), as well as for coordination via the Y-Balance test (rs = 0.58, p ≤ 0.0001) regarding the IKDC-SKF at three months. Additionally, DMD test results for coordination, strength and agility (Y-Balance test (rs = 0.50, p = 0.008), side hop test (rs = 0.54, p = 0.004) and single-leg vertical jump (rs = 0.44, p = 0.018)) correlate significantly with the IKDC-SKF at six months. No adverse events related to the use of the sensor-based application were reported. These findings confirm the clinical validity of a DMD to objectively quantify knee joint function for the first time. This will have further implications for clinical and therapeutic decision making, quality control and monitoring of rehabilitation measures as well as scientific research.

Development and validation of a clinical prediction model for return to work after arthroscopic anterior crucial ligament reconstruction.

BACKGROUND: Occupational reintegration after anterior cruciate ligament (ACL) rupture is an important clinical issue including economic and health-related perspectives. This study aims to develop and validate a clinical prediction model of return to work in patients with ACL reconstruction surgery considering evidence-based clinical, anthropometric and occupational factors. METHODS: Data of 562 patients with an ACL rupture receiving an arthroscopic ACL reconstruction were used for analysis. A model for the binary outcome of experiencing an inability to work period of less or more than 14 days (model 1), and a model for finding predictor variables that are linearly associated with a continuous longer inability to work period of over 14 days (model 2) was calculated. Pre-operative determinants including patient characteristics and peri-operative factors were used as predictors for both models. RESULTS: For model 1, the highest increase in odds was observed for the occupational type of work, followed by injury of the medial collateral ligament together with partial weight bearing. Small protective effects were observed for female sex, meniscal suture and work with light occupational strain. The type of occupational work, together with revision surgery, a longer duration of limited range of motion and the presence of cartilage therapy were risk factors for longer inability to work. Discrimination and calibration statistics were satisfactory in internal validation. CONCLUSION: Within the framework of clinical consideration, these prediction models will serve as an estimator for patients, their treating physicians and the socioeconomic partners to forecast the individual cost and benefit of ACL injury.