Load distribution in early osteoarthritis

Histological and immunohistochemical analyses of articular cartilage during onset and progression of pre- and early-stage osteoarthritis in a rodent model

Early diagnosis and treatment of pre- and early-stage osteoarthritis (OA) is important. However, the cellular and cartilaginous changes occurring during these stages remain unclear. We investigated the histological and immunohistochemical changes over time between pre- and early-stage OA in a rat model of traumatic injury. Thirty-six male rats were divided into two groups, control and OA groups, based on destabilization of the medial meniscus. Histological and immunohistochemical analyses of articular cartilage were performed on days 1, 3, 7, 10, and 14 postoperatively. Cell density of proteins associated with cartilage degradation increased from postoperative day one. On postoperative day three, histological changes, including chondrocyte death, reduced matrix staining, and superficial fibrillation, were observed. Simultaneously, a compensatory increase in matrix staining was observed. The Osteoarthritis Research Society International score increased from postoperative day seven, indicating thinner cartilage. On postoperative day 10, the positive cell density decreased, whereas histological changes progressed with fissuring and matrix loss. The proteoglycan 4-positive cell density increased on postoperative day seven. These findings will help establish an experimental model and clarify the mechanism of the onset and progression of pre- and early-stage traumatic OA.

Mesenchymal stem cell implantation provides short-term clinical improvement and satisfactory cartilage restoration in patients with knee osteoarthritis but the evidence is limited: a systematic review performed by the early-osteoarthritis group of ESSKA-European knee associates section

PURPOSE

Implantation of mesenchymal stem cells (MSCs) is a potential cell-based modality for cartilage repair. Currently, its clinical use largely surrounds focal cartilage defect repair and intra-articular injections in knee osteoarthritis. The MSCs' implantation efficacy as a treatment option for osteoarthritis remains contentious. This systematic review aims to evaluate studies that focused on MSCs implantation in patients with knee OA to provide a summary of this treatment option outcomes.

METHODS

A systematic search was performed in PubMed (Medline), Scopus, Cinahl, and the Cochrane Library. Original studies investigating outcomes of MSCs implantations in patients with knee OA were included. Data on clinical outcomes using subjective scores, radiological outcomes, and second-look arthroscopy gradings were extracted.

RESULTS

Nine studies were included in this review. In all included studies, clinical outcome scores revealed significantly improved functionality and better postoperative pain scores at 2-3 years follow-up. Improved cartilage volume and quality at the lesion site was observed in five studies that included a postoperative magnetic resonance imaging assessment and studies that performed second-look arthroscopy. No major complications or tumorigenesis occurred. Outcomes were consistent in both single MSCs implantation and concurrent HTO with MSCs implantation in cases with excessive varus deformity.

CONCLUSION

According to the available literature, MSCs implantation in patients with mild to moderate knee osteoarthritis is safe and provides short-term clinical improvement and satisfactory cartilage restoration, either as a standalone procedure or combined with HTO in cases with axial deformity. However, the evidence is limited due to the high heterogeneity among studies and the insufficient number of studies including a control group and mid-term outcomes.

LEVEL OF EVIDENCE

IV.

Implantable Shock Absorber Provides Superior Pain Relief and Functional Improvement Compared With High Tibial Osteotomy in Patients with Mild-to-Moderate Medial Knee Osteoarthritis: A 2-Year Report

OBJECTIVE

Up to 10 million Americans below the age of 65 years have symptomatic knee osteoarthritis (OA) and may not yet be candidates for arthroplasty. In response, a subcutaneous implantable shock absorber (ISA) that unloads the knee has been developed. The safety and effectiveness of ISA treatment were compared against a surgical unloading control, high tibial osteotomy (HTO).

DESIGN

This was a prospective open-label cohort study with a historical control arm. Subjects underwent ISA placement or HTO. The primary endpoint was a composite variable combining pain, function, specific adverse events, integrity of implant or hardware, and conversion to subsequent surgery. Pain and function outcomes (Western Ontario and McMaster Universities Arthritis Index scores) were assessed through 24 months. Adverse events were tracked.

RESULTS

The primary endpoint demonstrated superiority of the ISA arm versus the HTO arm, with 85.6% of ISA subjects meeting all criteria compared with 65.5% of HTO subjects. In addition, all 5 secondary endpoints showed superiority of ISA over HTO. At 24 months, the proportions of subjects considered responders were 95.8% (ISA) versus 87.9% (HTO) for pain and 91.7% (ISA) versus 81.3% (HTO) for function. The ISA procedure was well tolerated, with 13.4 days to full weightbearing status versus 58.0 days for the HTO arm.

CONCLUSIONS

Treatment with an ISA demonstrated noninferiority and superiority versus treatment with HTO in subjects aged 25-65 years who had OA of the medial knee. Treatment with ISA has high clinical benefit and is durable through at least 24 months.

An implantable shock absorber yields an 85% survival-from-arthroplasty rate through 5 years in working-age patients with medial compartment knee osteoarthritis

PURPOSE

To evaluate the 5-year rate of survival without undergoing arthroplasty or high tibial osteotomy (HTO) in subjects with mild-to-moderate medial compartment knee osteoarthritis (OA) who were treated with an implantable shock absorber (ISA) system.

METHODS

Three prospective, sequential, multicenter, international, single-arm clinical trials were conducted comprising subjects who received an ISA for symptomatic medial knee OA after failing ≥ 6 months of conservative therapy. Study outcomes were analyzed cumulatively and by enrollment group when all subjects' follow-up data exceeded the 2-year threshold after ISA implantation. Primary outcome was survival rate without conversion to arthroplasty/HTO. Secondary outcomes were changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function scores after ISA implantation.

RESULTS

All 171 enrolled subjects (age 51 ± 9 years, body-mass index 28.5 ± 3.5 kg/m², 38% female; study knee Kellgren-Lawrence score 2.7 ± 0.9 points) were followed for a minimum of 2, and up to 5, years after device implantation. Overall, 90.6% (155/171) of subjects survived without requiring arthroplasty/HTO at last follow-up (mean 3.2 ± 1.6 years). The Kaplan-Meyer median 3- and 5-year survival-without-arthroplasty point estimates were 89.8% (95% CI 86.5‒95.7%) and 84.9% (95% CI 75.1‒91.1%), respectively. The median 3-year estimated survival rate for the most recent study (n = 81) was 97.3%. The mean WOMAC Pain score decreased 71% from baseline to last follow-up after ISA implantation, from 58 ± 13 to 16 ± 17 points (p < 0.0001). The Function score improved 69%, decreasing from 56 ± 18 to 17 ± 17 points (p < 0.0001).

CONCLUSIONS

In younger patients with mild-to-moderate symptomatic medial compartment knee OA, implantation of the ISA device resulted in a 5-year survival rate of 85% from undergoing arthroplasty or HTO. The ISA system may be an effective treatment option for working-age patients with medial knee OA who are not candidates for or do not desire more invasive surgical approaches.

LEVEL OF EVIDENCE

II.

Unloader bracing in osteoarthritis of the knee - Is there a direct effect on the damaged cartilage?

BACKGROUND

Unloading knee braces represent a conservative treatment option for non-pharmalogical management of unicompartmental osteoarthritis of the knee. Though there is consensus on the clinical effectiveness of unloading, the effect mechanism of bracing remains part of a debate. Our study was designed to assess the effect of unloader bracing on damaged cartilage via MRI cartilage mappings.

METHODS

Fourteen patients (7 female, 7 male, mean age 43.1 ± 9.4 years) with unicompartmental cartilage wear in knees with varus or valgus malalignment were enrolled. Clinical scores, radiographs and MR-graphic properties (T2/T2* mapping, T1 Delayed Gadolinium Enhanced MRI of the cartilage (dGEMRIC) mapping, high-resolution PDw sequences) of knee cartilage were recorded before and three months after brace use.

RESULTS

Bracing the knees for a mean of 14.4 ± 2.0 weeks (range 11 to 18 weeks) resulted in significant pain reduction (VAS changed from 5.9 ± 2.0 to 2.0 ± 1.3, p < 0.001) and improvement in knee function (KOOS increased from 42.1 ± 22.7 to 64.8 ± 18.7, p < 0.001). In the affected cartilage regions T2 relaxation times significantly decreased from 56.1 ± 11.4 ms to 46.5 ± 11.2 ms (p < 0.05). No changes in T1-dGEMRIC and T2* relaxation times, thickness or the extent of the damaged cartilage area could be detected.

CONCLUSIONS

Our results suggest, that unloader bracing improves the biochemical properties of the damaged cartilage by increasing collagen and proteoglycan concentration as well as decreasing the cartilage edema.

Two-year clinical results of a novel load redistribution device for the treatment of medial knee OA

PURPOSE

A potential method to relieve the pain from medial osteoarthritis of the knee is to offload the medial compartment. The Latella^™ Knee Implant is a novel device designed to offload the medial compartment. The objective of the Cotera-1 study was to evaluate the preliminary safety and feasibility of the Latella implant to treat patients with medial OA of the knee, by a 2-year follow-up of a prospective multicenter feasibility study (Cotera-1) performed in the Netherlands and UK METHODS: In this first-in-man study, 11 participants received the Latella implant and were followed for 2 years, documenting physician assessment, Patient-Reported Outcome (PRO) scoring (KOOS, IKDC, Kujala, SF-36); Patient Global Assessment (PGA), radiographic analysis and MRI analysis, complications, reoperation rate and hip-knee-ankle axis.

RESULTS

The Latella Knee Implant system proved to be well tolerated and demonstrated a low-risk safety profile up to 24 months post-treatment. A responder analysis was performed of the subjects who still had the Latella implanted at 24-month time point (n = 9). Based on a MCID of eight for KOOS pain sub-scale, 78% of the subjects at the 24 month time point would be considered as responders. Similarly, based on improvement in the medial knee pain compared to baseline using the NRS scale of 1-10, 89% of the subjects at the 24-month time point would be considered as responders. Two patients were revised during follow-up: one for arthrofibrosis and one converted to TKA for progression of OA.

CONCLUSIONS

The early clinical experience with the Latella Knee Implant in this pilot feasibility study has been encouraging. It appears to be a safe implant with possible effect on medial OA. Additional studies need to be performed to assess the safety and efficacy of the procedure in a larger patient population.

LEVEL OF EVIDENCE

II.

Optimization of backpack loads using gait parameters in school boys

BACKGROUND

Backpacks are an efficient way of manual carriage used by people of all ages, and is commonly used by schoolchildren. Carrying heavy backpacks may result in cumulative trauma later in life due to biomechanical adaptations during gait. Gait parameters are known to be sensitive to force vectors, which can be altered by load carrying. This study attempts to find the most favorable backpack weight using gait changes as an indicator.

METHODS

This was an observational study conducted on twenty typically developing boys aged between 9 and 14 years. Gait analysis was done using standard recommendations, with increasing backpack loads with respect to their body weights. Gait cycles were captured using video cameras and analyzed using Kinovea0.8.25 motion analyzing software.

RESULTS

As the backpack load increased, significant kinematic changes were noted in the child's ankle, knee, and hip joints. These changes were evident when the backpack load increased beyond 15% of their body weight.

CONCLUSIONS

This study concludes that the optimum weight that can be carried without having an impact on dynamic posture will be less than 15% of the body weight.

Two-Year Results of the PHANTOM High Flex Trial: A Single-Arm Study on the Atlas Unicompartmental Knee System Load Absorber in Patients With Medial Compartment Osteoarthritis of the Knee

The Atlas Knee System was designed to fill the gap between no longer effective conservative treatments and more invasive surgery for young patients with medial knee osteoarthritis (OA). This article reports on the 2-year results of a single-arm study of 26 subjects who previously reported favorable clinical outcomes 1 year post implantation. Western Ontario and McMaster Universities Osteoarthritis Index pain and function scores improved by a clinically meaningful amount relative to baseline, and subjects had a return to normal range of motion. This study confirmed that the benefit of a joint unloading device in the management of young patients with medial knee OA is maintained over 2 years. This trial was registered with ClinicalTrials.gov (NCT02711254).

Preliminary study on a novel minimally invasive extra-articular implant for unicompartmental knee osteoarthritis

The purpose of this research was to study the efficacy of a novel implant for osteoarthritic knees. This implant is designed to eliminate excessive loads through the knee and to provide suitable conditions for possible tibiofemoral cartilage repair. The implant was designed for the medial side of the knee joint. Finite Element Analysis (FEA) was performed for an extended knee position of the knee joint. Von Mises stress and contact pressure distributions on the medial and lateral compartments were investigated as well as stress distributions throughout the implant's plates. Comparison of FEA results with and without the implant showed that the maximum von Mises stress and contact pressure experienced by the femoral cartilage were reduced by 40% and 35%, respectively, after introducing the implant. Furthermore, after attaching the implant, the femur was slightly abducted and more stress and pressure were perceived in the lateral compartment compared to the model without implant. The maximum von Mises stress in the implant (96 MPa) was far lower than the yield strength of Ti-6Al-4V (∼900 MPa), the selected material for manufacturing the implant. According to the above points, this initial study shows promise for the new prosthesis.

Clinical Management in Early OA

Knee osteoarthritis affects an important percentage of the population throughout their life. Several factors seem to be related to the development of knee osteoarthritis including genetic predisposition, gender, age, meniscal deficiency, lower limb malalignments, joint instability, cartilage defects, and increasing sports participation. The latter has contributed to a higher prevalence of early onset of knee osteoarthritis at younger ages with this active population demanding more consistent and durable outcomes. The diagnosis is complex and the common signs and symptoms are often cloaked at these early stages. Classification systems have been developed and are based on the presence of knee pain and radiographic findings coupled with magnetic resonance or arthroscopic evidence of early joint degeneration. Nonsurgical treatment is often the first-line option and is mainly based on daily life adaptations, weight loss, and exercise, with pharmacological agents having only a symptomatic role. Surgical treatment shows positive results in relieving the joint symptomatology, increasing the knee function and delaying the development to further degenerative stages. Biologic therapies are an emerging field showing early promising results; however, further high-level research is required.

Intraoperative validation of quantitative T2 mapping in patients with articular cartilage lesions of the knee

OBJECTIVE

The aim of this study was to compare T2 relaxation times of knee cartilage with intraoperative results for the assessment of early osteoarthritis (OA) and to define T2 values for the differentiation between healthy and degenerated cartilage.

DESIGN

Twenty-one patients with cartilage lesions or moderate OA were examined using 3T magnetic resonance imaging (MRI). In this prospective study, a total of 882 regions of interest (ROIs) were examined by a sagittal, multi-echo, spin-echo T2 sequence and a morphological high-resolution three-dimensional, fat-saturated proton-density space sequence. Cartilage lesions were identified arthroscopically, graded by the International Cartilage Repair Society (ICRS) score in 42 defined ROIs per patient and consecutively compared with mean T2 values using analysis of variance and Spearman's rank correlation test. Receiver operating characteristics (ROC) curves were developed to identify threshold T2 values to differentiate between the ICRS grades.

RESULTS

A total of 882 ROIs were examined and graduated in ICRS score 0 (67.3%), 1 (25.2%), 2 (6.2%) and the merged ICRS 3 and 4 (1.0%). T2 values increased with increasing grade of cartilage damage with a statistically significant positive correlation between T2 values and ICRS scores. A T2 value threshold of 47.6 ms was identified to differentiate between ICRS score 0 (normal) and all other grades (ROC curve analysis).

CONCLUSION

T2 mapping might provide a diagnostic tool for the detection of early knee-joint cartilage damage and for the non-invasive differentiation between ICRS grades by MRI in clinical practice.

A Novel Implant System for Unloading the Medial Compartment of the Knee by Lateral Displacement of the Iliotibial Band

Background:

Medial knee osteoarthritis (OA) typically occurs with excessive mechanical load within the medial compartment, resulting in degeneration of the articular cartilage.

Purpose:

A novel extracapsular implant (Latella Knee Implant) has been developed to unload the medial compartment of the knee. The implant displaces the iliotibial band (ITB) over the lateral femoral condyle, thereby increasing its effective moment arm, resulting in a transfer of load from the medial compartment to the lateral compartment of the knee. A cadaveric study was performed to evaluate the effect of altering the moment arm of the ITB on knee biomechanics.

Study Design:

Controlled laboratory study.

Methods:

A 6-degrees-of-freedom robotic testing system was utilized to measure medial and lateral compartment loads in 8 fresh-frozen cadaveric knees at various ITB loads and knee flexion angles. Measurements were made with and without the implant in place. The system measured the compartment forces at flexion angles between 0° and 30° under 3 simulated loading conditions (300 N quadriceps, 100 N hamstrings, and [1] 0 N ITB, [2] 50 N ITB, [3] 100 N ITB).

Results:

Lateral displacement of the ITB between 15 and 20 mm resulted in medial compartment unloading between 34% and 65%.

Conclusion:

Unloading the medial compartment with this novel implant has the potential to address the treatment gap for patients with medial knee OA.

Clinical Relevance:

Currently, there exists a treatment gap for patients with medial compartment OA who have exhausted conservative management but whose disease and symptoms do not warrant more invasive surgical procedures. An extracapsular implant to unload the medial compartment could fill this treatment gap by providing patients and surgeons with a less invasive option for early to mid-stage OA. Unloading the medial compartment may alleviate pain and improve function, allowing patients with early-stage medial OA to remain active longer prior to considering more invasive options such as arthroplasty.