Knee Joint Distraction Research Articles

‘The unexpected journey’: a qualitative interview study exploring patient and health professionals experiences of participating in the knee arthroplasty versus joint distraction study (KARDS)

ObjectiveThe aim of the knee arthroplasty versus joint distraction (KARDS) randomised trial was to investigate whether knee joint distraction (KJD) is non-inferior to knee arthroplasty, also known as knee replacement...

Two-year post-distraction cartilage-related structural improvement is accompanied by increased serum full-length SIRT1

BackgroundPreviously, fragments from Sirtuin 1 (SIRT1) were identified in preclinical and clinical samples to display an increase in serum levels for N-terminal (NT) SIRT1 vs. C-terminal (CT) SIRT1, indicative of early signs of OA. Here we tested NT/CT SIRT1 levels as well as a novel formulated sandwich assay to simultaneously detect both domains of SIRT1 in a manner that may inform us about the levels of full-length SIRT1 in the circulation (flSIRT1) of clinical cohorts undergoing knee joint distraction (KJD).MethodsWe employed an indirect ELISA assay to test NT- and CT-SIRT1 levels and calculated their ratio. Further, to test flSIRT1 we utilized novel antibodies (Ab), which were validated for site specificity and used in a sandwich ELISA method, wherein the CT-reactive served as capture Ab, and its NT-reactive served as primary detection Ab. This method was employed in human serum samples derived from a two-year longitudinal study of KJD patients. Two-year clinical and structural outcomes were correlated with serum levels of flSIRT1 compared to baseline.ResultsAssessing the cohort, exhibited a significant increase of NT/CT SIRT1 serum levels with increased osteophytes and PIIANP/CTX-II at baseline, while a contradictory increase in NT/CT SIRT1 was associated with less denuded bone, post-KJD. On the other hand, flSIRT1 exhibited an upward trend in serum level, accompanied by reduced denuded bone for 2-year adjusted values. Moreover, 2 year-adjusted flSIRT1 levels displayed a steeper linear regression for cartilage and bone-related structural improvement than those observed for NT/CT SIRT1.ConclusionsOur data support that increased flSIRT1 serum levels are a potential molecular endotype for cartilage-related structural improvement post-KJD, while NT/CT SIRT1 appears to correlate with osteophyte and PIIANP/CTX-II reduction at baseline, to potentially indicate baseline OA severity.

Assessment of clinical, functional and radiological outcomes in young patients with grade 3 and 4 osteoarthritis of the knee joint undergoing knee joint distraction with and without arthroscopic debridement and chondroplasty-a prospective, comparative and randomized controlled study

Background: Treatment of severe osteoarthritis (OA) in relatively young patients is challenging. Although successful, Total knee arthroplasty (TKA) has a limited lifespan, with the risk of revision surgery, especially in active young patients. Our study aims to assess the comparative clinical, functional and radiological outcomes of knee joint distraction (KJD) with and without arthroscopic debridement and chondroplasty in OA of knee in the young, in a randomized controlled trial. Methods: Our study was a prospective randomized trial with equal allocation. A total of 160 patients needing intervention for knee arthritis, in the age group of <55 years were included as per the inclusion criteria, and were randomized into 2 groups. Group A included 80 patients who underwent KJD alone. Group B included 80 patients who underwent KJD with arthroscopic debridement and chondroplasty. All patients were followed up to 24 months post intervention. Clinical (Visual analogue scale-VAS), functional (Western Ontario and McMaster universities OA index-WOMAC) and radiological (Joint space width-JSW) outcomes were then compared and assessed. Results: Both the groups showed statistically significant improvement of clinical, functional and radiological outcome scores compared to baseline levels. The mean improvement in KJD+SCOPY group was statistically superior to that of KJD group with regard to clinical and functional outcome scores; however, the radiological improvement though being statistically significant in both groups compared to baseline levels, but one group was not superior to that of other. Conclusions: KJD in patients with OA of knee (Kellegren Lawrence grade 3-4) aged <55 years results in improvement of clinical, functional and radiological parameters at 2 year follow up. Addition of arthroscopic debridement and chondroplasty to KJD makes it superior to KJD alone in terms of improvement in clinical, functional and radiological outcomes. We recommend arthroscopic debridement and chondroplasty coupled with KJD for compliant patients of less than 55 years with grade 3-4 OA of the knee.

Knee Joint Distraction with an External Fixator Requires Further Investigation

No abstract

New concept of orthosis treatment for knee osteoarthritis: Clinical and radiological outcomes.

Given the increasing numbers of young patients with knee osteoarthritis there is a need for treatments that can postpone a joint prosthesis (total knee replacement). As an alternative to the effective yet invasive knee joint distraction procedure, a knee orthosis was developed aiming to unload the affected knee and improving synovial fluid flow. The aim of this study was to examine the effectiveness of using a load-reducing orthosis for two months on functioning, pain, and disease progression (e.g. amount of damaged cartilage) in patients with symptomatic osteoarthritis of the knee for at least one year. This is an interventional single-center pilot study. Ten patients with symptomatic osteoarthritis of one knee (5males/5 females; median age 57; age range 42-59) used a custom-made orthosis for 60 days during daily life activities that involved knee loading (e.g. standing, walking, but not during stair climbing). Cycling was not allowed. Clinical outcomes were assessed up to 24 months after intervention at 6 timepoints using patient reported-outcome measures Western Ontario and McMaster Universities Osteoarthritis (WOMAC) range 0-100; Visual Analogue Scale (VAS), range 0-100 for pain. Minimum joint space width (mJSW) was assessed using knee images digital analysis (KIDA) and articular cartilage volume with magnetic resonance imaging (MRI) using custom software at baseline and at 12 and 24 months follow-up. Clinically beneficial effects were found for functioning (WOMAC improvement compared to baseline ranged between 18 points at 3 months follow-up and 31 points at 12 months follow-up, with only the 24-months follow-up (improvement of 27 points) not reaching statistical significance (p< 0.05)) and for pain (VAS improvement compared to baseline at follow-up time points ranged between 41-56 points; all p< 0.05). No improvements in mJSW- or MRI-derived parameters were found. This study demonstrates that use of a custom-made knee-unloading orthosis for 60 days can result in improved functional ability and decrease in pain in relatively young patients with knee osteoarthritis. No effect on disease progression could be evidenced.

The Feasibility of Hinged Knee Arthrodiastasis for Cartilage Regeneration: A Systematic Review of the Literature.

Knee joint distraction (KJD) is a potential technique for cartilage regeneration in young patients with osteoarthritis of the knee. Static distraction has been utilised typically; however, a significant proportion of patients complain of knee stiffness post-distractor removal. The use of a hinged distractor may reduce the duration and severity of post-treatment knee stiffness by maintaining the range of motion during distraction. Furthermore, improved cartilage regeneration has been demonstrated in hinged ankle joint distraction as compared to static, and this may also be demonstrated at the knee. An evidence review was undertaken to inform further research and a potential change in practice. A systematic review of all primary research on hinged knee joint distraction for cartilage regeneration. An online systematic search of citation databases was conducted. Quality assessment and data extraction were undertaken by two separate researchers. The literature search returned a small number of relevant studies, of which 7 were included. Three of these were animal studies, two cadaveric and two case series. The study quality was low or very low. There was significant methodological heterogeneity with difficulties encountered in the transfer of constructs from animal and cadaveric studies to humans. Issues faced included difficulties with hinge placement and pin site pain in motion. The feasibility of hinged knee joint distraction has yet to be proven. Any further research attempting to establish the benefits of hinged-over static knee distraction will have to take construct design considerations into account. Lineham B, van Duren B, Harwood P, et al. The Feasibility of Hinged Knee Arthrodiastasis for Cartilage Regeneration: A Systematic Review of the Literature. Strategies Trauma Limb Reconstr 2023;18(1):37-43.

Surgical interventions for symptomatic knee osteoarthritis: a network meta-analysis of randomized control trials

BackgroundMultiple surgical interventions exist for the treatment of symptomatic knee osteoarthritis, but the surgeon and patient may often have difficulty deciding which interventions are the best option.MethodsWe conducted a systematic review to identify randomized clinical trials (RCTs) that compared complications, revisions, reoperations, and functional outcomes among TKA (total knee arthroplasty), UKA (unicompartmental knee arthroplasty), HTO (high tibial osteotomy), BCA (bicompartmental knee arthroplasty), BIU (bi-unicompartmental knee arthroplasty), and KJD (knee joint distraction). The PubMed, Embase, and Cochrane databases were reviewed for all studies comparing two or more surgical interventions. Direct-comparison meta-analysis and network meta-analysis (NMA) were performed to combine direct and indirect evidence. The risk of bias was assessed using the revised Cochrane risk of bias tool for RCTs.ResultsThis NMA and systematic review included 21 studies (17 RCTs), with a total of 1749 patients. The overall risk-of-bias assessment of the RCTs revealed that 7 studies had low risk, 5 had some concerns, and 9 had high risk. SUCRA (the surface under the cumulative ranking curve) rankings revealed that KJD had the greatest risk of appearing postoperative complications, revisions, and reoperations, and UKA or TKA had the lowest risk. The majority of comparisons among various treatments showed no difference for functional outcomes.ConclusionEach surgical intervention is noninferior to other treatments in functional outcomes, but UKA and TKA are better options to treat OA according to SUCRA rankings by comparing complications, revisions, and reoperations. KJD is an imperfect option for treating OA. Other treatments should be carefully considered for each patient in accordance with their actual conditions. However, this conclusion is limited by the selection of reviewed publications and individual variation of surgical indications for patients.Trial registrationThis study was registered with Research Registry (reviewregistry1395).

JOINT REPAIR EVALUATED ON RADIOGRAPHS IS ASSOCIATED WITH PAIN AND SYNOVIAL FLUID MARKER CHANGES AFTER KNEE JOINT DISTRACTION TREATMENT

Knee joint distraction (KJD) has been associated with clinical and structural improvement and synovial fluid (SF) marker changes. However, structural changes have not yet been shown satisfactorily in regular care, since radiographic acquisition was not fully standardized. AI-based modules have shown great potential to reduce reading time, increase inter-reader agreement and therefore function as a tool for treatment outcome assessment. The objective was to analyse structural changes after KJD in patients using this AI-based measurement method, and relate these changes to clinical outcome and SF markers.20 knee OA patients (&lt;65 years old) were included in this study. KJD treatment was performed using an external fixation device, providing 5 mm distraction for 6 weeks. SF was aspirated before, during and immediately after treatment. Weight-bearing antero-posterior knee radiographs and WOMAC questionnaires were collected before and ~one year after treatment. Radiographs were analysed with the Knee Osteoarthritis Labelling Assistant (KOALA, IB Lab GmbH, Vienna, Austria), and 10 pre-defined biomarker levels in SF were measured by immunoassay. Radiographic one-year changes were analysed and linear regression was used to calculate associations between changes in standardized joint space width (JSW) and WOMAC, and changes in JSW and SF markers.After treatment, radiographs showed an improvement in Kellgren-Lawrence grade in 7 of 16 patients that could be evaluated; 3 showed a worsening. Joint space narrowing scores and continuous JSW measures improved especially medially. A greater improvement in JSW was significantly associated with a greater improvement in WOMAC pain (β=0.64;p=0.020). A greater increase in MCP1 (β=0.67;p=0.033) and lower increase in TGFβ1 (β=-0.787;p=0.007) were associated with JSW improvement.Despite the small number of patients, also in regular care KJD treatment shows joint repair as measured automatically on radiographs, significantly associated with certain SF marker change and even with clinical outcome.

Artificial intelligence in osteoarthritis: repair by knee joint distraction shows association of pain, radiographic and immunological outcomes.

Knee joint distraction (KJD) has been associated with clinical and structural improvement and SF marker changes. The current objective was to analyse radiographic changes after KJD using an automatic artificial intelligence-based measurement method and relate these to clinical outcome and SF markers. Twenty knee osteoarthritis patients were treated with KJD in regular care. Radiographs and WOMAC were collected before and ∼1 year post-treatment. SF was aspirated before, during and after treatment; biomarker levels were assessed by immunoassay. Radiographs were analysed to obtain compartmental minimum and standardized joint space width (JSW), Kellgren-Lawrence (KL) grades, compartmental joint space narrowing (JSN) scores, and osteophytosis and sclerosis scores. Results were analysed for the most affected compartment (MAC) and least affected compartment. Radiographic changes were analysed using the Wilcoxon signed rank test for categorical and paired t-test for continuous variables. Linear regression was used to calculate associations between changes in JSW, WOMAC pain and SF markers. Sixteen patients could be evaluated. JSW, KL and JSN improved in around half of the patients, significant only for MAC JSW (P < 0.05). MAC JSW change was positively associated with WOMAC pain change (P < 0.04). Greater monocyte chemoattractant protein 1 (MCP-1) and lower TGFβ-1 increases were significantly associated with changes in MAC JSW (P < 0.05). MCP-1 changes were positively associated with WOMAC pain changes (P < 0.05). Automatic radiographic measurements show improved joint structure in most patients after KJD in regular care. MAC JSW increased significantly and was associated with SF biomarker level changes and even with improvements in pain as experienced by these patients.

Progress on knee cartilage repair by knee joint distraction

Knee joint distraction is a new technology for the treatment of knee osteoarthritis in recent years. It could reduce knee pain and improve knee function, which is inseparable from the role of cartilage repair. The mechanism and influencing factors of knee joint distraction in repairing cartilage are the focus of current research. In this paper, the author reviewed literature and found that knee joint distraction could reduce knee joint load and provide a appropriate mechanical environment for cartilage repair, and it is resulting hydrostatic pressure fluctuation in the knee joint not only helps cartilage to absorb nutrients, but also promotes cartilage formation genes and inhibits cartilage matrix degrading enzyme gene expression. In addition, knee joint distraction creates conditions for synovial mesenchymal stem cells to be collected to cartilage injury, and improves ability of synovial mesenchymal stem cells to proliferate and differentiate into a chondrogenic lineage. Knee joint distraction could reduce inflammatory reaction and cartilage injury of knee joint by reducing content of inflammatory factors and inhibiting expression of inflammatory genes. At present, it is known that the factors affect repair of cartilage by knee joint distraction include, increasing weight-bearing activity and height and time of distraction is helpful for cartilage repair, male patients and patients with higher severity of knee osteoarthritis have better cartilage repair effect after knee joint distraction.The better efficacy of cartilage repair on the first year after knee joint distraction predicts a higher long-term survival rate of knee joint distraction with knee preservation. However, the research on the above hot spots is only at the initial stage and further exploration is still needed, in order to better guide clinical application of knee joint distraction.

The catabolic-to-anabolic shift seen in the canine osteoarthritic cartilage treated with knee joint distraction occurs after the distraction period.

BackgroundCartilage regenerative mechanisms initiated by knee joint distraction (KJD) remain elusive. Animal experiments that are representative for the human osteoarthritic situation and investigate the effects of KJD at consecutive time points could be helpful in this respect but are lacking. This study investigated the effects of KJD on the osteoarthritic joint of dogs on two consecutive timepoints.MethodsOsteoarthritis was bilaterally induced for 10 weeks in 12 dogs using the groove model. Subsequently, KJD was applied to the right hindlimb for 8 weeks. The cartilage, subchondral bone and synovial membrane were investigated directly after KJD treatment, and after 10 weeks of follow-up after KJD treatment. Macroscopic and microscopic joint tissue alterations were investigated using the OARSI grading system. Additionally, proteoglycan content and synthesis of the cartilage were assessed biochemically. RT-qPCR analysis was used to explore involved signaling pathways.ResultsDirectly after KJD proteoglycan and collagen type II content were reduced accompanied by decreased proteoglycan synthesis. After 10 weeks of follow-up, proteoglycan and collagen type II content were partly restored and proteoglycan synthesis increased. RT-qPCR analysis of the cartilage suggests involvement of the TGF-β and Notch signalling pathways. Additionally, increased subchondral bone remodelling was found at 10 weeks of follow-up.ConclusionWhile the catabolic environment in the cartilage is still present directly after KJD, at 10 weeks of follow-up a switch towards a more anabolic joint environment was observed. Further investigation of this timepoint and the pathways involved might elucidate the regenerative mechanisms behind KJD.The Translational Potential of this ArticleFurther elucidation of the regenerative mechanisms behind KJD could improve the existing KJD treatment. Furthermore, these findings could provide input for the discovery or improvement of other joint regenerative treatment strategies.

Clinical and cost-effectiveness of Knee Arthroplasty versus Joint Distraction for Osteoarthritis (KARDS): protocol for a multicentre, phase III, randomised control trial

IntroductionKnee replacement (KR) is a clinically proven procedure typically offered to patients with severe knee osteoarthritis (OA) to relieve pain and improve quality of life. However, artificial joints fail over...

Subchondral bone changes after joint distraction treatment for end stage knee osteoarthritis

Increased subchondral cortical bone plate thickness and trabecular bone density are characteristic of knee osteoarthritis (OA). Knee joint distraction (KJD) is a joint-preserving knee OA treatment where the joint is temporarily unloaded. It has previously shown clinical improvement and cartilage regeneration, indicating reversal of OA-related changes. The purpose of this research was to explore 3D subchondral bone changes after KJD treatment using CT imaging. Twenty patients were treated with KJD and included to undergo knee CT imaging before, one, and two years after treatment. Tibia and femur segmentation and registration to canonical surfaces were performed semi-automatically. Cortical bone thickness and trabecular bone density were determined using an automated algorithm. Statistical parametric mapping (SPM) with two-tailed F-tests was used to analyze whole-joint changes. Data was available of 16 patients. Subchondral cortical bone plate thickness and trabecular bone density were higher in the weight-bearing region of the most affected compartment (MAC; mostly medial). Especially the MAC showed a decrease in thickness and density in the first year after treatment, which was sustained towards the second year. KJD treatment results in bone changes that include thinning of the subchondral cortical bone plate and decrease of subchondral trabecular bone density in the first two years after treatment, potentially indicating a partial normalization of subchondral bone.

Knee Joint Distraction in a Dog as Treatment for Severe Osteoarthritis

AbstractOsteoarthritis (OA) is the most common joint disease diagnosed in veterinary practice. There is no cure; where conservative treatment fails, a joint prosthesis is the last resort. In human OA patients, temporary distraction is a joint-preserving treatment which provides clinical and structural benefits, and postpones the need for total knee replacement for up to 9 years. In this single case, feasibility of knee joint distraction (KJD) was assessed in a 9-year-old female Dobermann with severe OA. Osteoarthritis of the left stifle joint was diagnosed clinically and radiographically. Knee joint distraction was applied for 7 weeks using a custom-made, hinged, external fixator. Follow-up of 1 year included owner questionnaires, orthopaedic examination, radiography, and force plate analysis. Additionally, synovial fluid biomarkers were assessed. Application and removal of the KJD frame were successfully accomplished without surgical complications. During KJD, the dog tolerated the frame well and maintained the use of the left hindlimb. Mild pin tract infection developed during the distraction period, which responded well to oral antibiotic medications. Owners reported clinical improvement during KJD and the follow-up period. This was confirmed by force plate analysis, demonstrating improvement from 3 months and onward. KJD proved to be a feasible strategy to treat end-stage OA in this single case; clinical efficacy remains to be determined in a larger cohort.

JOINT REPAIR EVALUATED AUTOMATICALLY ON RADIOGRAPHS IS ASSOCIATED WITH PAIN AND SYNOVIAL FLUID MARKER CHANGES AFTER KNEE JOINT DISTRACTION TREATMENT

Knee joint distraction (KJD) has been associated with clinical and structural improvement and synovial fluid (SF) marker changes. However, structural changes have not yet been shown satisfactorily in regular care, since radiographic acquisition was not fully standardized. AI-based modules have shown great potential to reduce reading time, increase inter-reader agreement and therefore function as a tool for treatment outcome assessment. To 1) analyze structural changes after KJD in patients using this AI-based measurement method, and relate these changes to 2) clinical outcome and 3) SF markers. 20 knee OA patients (<65 years old) were included in this study. KJD treatment was performed using an external fixation device, providing 5 mm distraction for 6-7 weeks. SF was aspirated before, during and immediately after treatment. Weight-bearing antero-posterior knee radiographs and WOMAC questionnaires were collected before and ∼one year after treatment. Radiographs were analyzed with the Knee Osteoarthritis Labelling Assistant (KOALA, IB Lab GmbH, Vienna, Austria) to obtain whole-joint KL grade, medial and lateral joint space narrowing (JSN) scores, compartmental continuous minimum and standardized JSW, and osteophytes and sclerosis scores of the medial and lateral tibia and femur. 10 Pre-defined biomarker levels in SF were measured by immunoassay. Radiographic one-year changes were analyzed using Wilcoxon Signed Rank tests for categorical and paired t-test for continuous variables. Linear regression was used to calculate associations between changes in standardized joint space width (JSW) and WOMAC, and changes in JSW and SF markers. After treatment, radiographs showed an improvement in Kellgren-Lawrence grade in 7 of 16 patients that could be evaluated; 3 showed a worsening. Joint space narrowing scores and continuous JSW measures improved especially medially. Radiographic changes were not statistically significant (p>0.1), except for the medial JSW (p<0.05). A greater improvement in JSW was significantly associated with a greater improvement in WOMAC pain (β=0.64; p=0.020). A greater increase in MCP1 (β=0.67; p=0.033) and lower increase in TGFβ1 (β=-0.787; p=0.007) were associated with JSW improvement. Despite the small number of patients, also in regular care KJD treatment shows joint repair as measured automatically on radiographs, significantly associated with certain SF marker change and even with clinical outcome. Versus Arthritis project grant (20783), Centre for OA Pathogenesis Versus Arthritis (grants 20205 and 21621), the Kennedy Trust for Rheumatology Research, and ReumaNederland (ISP14-3-301/16-1-404). CS, EB, MD: ImageBiopsyLab GmbH. NA CORRESPONDENCE ADDRESS: m.p.jansen-36@umcutrecht.nl

Clinical Feasibility of Personalized Articulating Knee Joint Distraction

Introduction: Knee Joint Distraction (KJD) is a joint preserving procedure that can postpone arthroplasty in case of knee osteoarthritis. Distraction is applied with an external rigid fixation device for six weeks. To reduce the burden during treatment due to the absence of joint flexion, we developed a personalized articulating KJD-device. Its technical feasibility, joint-specific motion reproduction, was previously pre-clinically demonstrated. In this study, clinical feasibility of this new device was tested in three patients. Materials and Methods: Patients received conventional KJD treatment with a rigid distraction device. After two to four weeks, the device was removed during a one-day hospital visit and the joint was flexed on a Continuous Passive Motion (CPM) device until 30 degrees of flexion was reached, or motion became too painful. Subsequently, the articulating frame was assembled and personalized with custom hinge parts based on a non-invasive joint motion measurement. Weight-bearing and non-weight-bearing radiographs were intended to be taken at 0, 15, and 30 degrees of flexion for joint space width measurements. Finally, the articulating device was replaced by the rigid distractor and conventional treatment was continued. Results: For none of the patients, the articulating distractor could be personalized adequately. Insufficient joint motion was achieved during CPM due to intolerable pain at the pin sites. Conclusions: Despite confirmation of joint-specific articulating distraction on cadaveric legs, clinical feasibility could not be demonstrated, mainly due to painful motion of soft tissues along the bone pins. Safe and solid anatomical location of pins is considered to hamper articulating distraction.

Clinical outcomes of knee joint distraction combined with marrow stimulation procedures for patients with advanced knee osteoarthritis

BackgroundKnee joint distraction (KJD) has received much attention as a joint preserving surgery, especially in young patients with advanced knee osteoarthritis (OA). MethodsThis study included 16 patients with advanced knee OA who underwent KJD combined with marrow stimulating techniques and were followed up for more than 2 years. The patients’ clinical scores, including the Japanese Orthopaedic Association (JOA) score, Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales, ROM, joint space width, and semiquantitative MRI were evaluated. The factors affecting clinical outcomes were analyzed. ResultsPostoperatively, the JOA score and the individual scores of the KOOS subscales improved significantly (JOA score: P = 0.0028, KOOS-symptoms: P = 0.0016, -pain: P = 0.0011, -ADL: P = 0.0009, -sports/recreation: P = 0.0144, and -QOL: P = 0.0034). Although the extension of the knee joint did not change throughout the follow-up period, flexion of the joint deteriorated at the time of device removal but recovered to the preoperative level at the final follow-up. Preoperative joint space width was 2.4 ± 2.0 mm and at the final follow-up, it increased to 3.3 ± 1.5 mm, showing statistically significant improvement (P = 0.034). The postoperative semiquantitative MRI score also improved significantly (from 6.0 ± 3.0 to 42.1 ± 28.7, P = 0.0001). A high BMI was associated with a poor clinical outcome. ConclusionAlthough the effect of marrow stimulating techniques for cartilage repair was not well clarified and the complication rate was high, the clinical and radiographic outcomes showed significant improvement after KJD combined with marrow stimulating techniques in patients with advanced knee OA. However, we should be careful about suggesting this procedure in obese patients.

Comparison of Mechanical Performance between Circular Frames and Biplanar Distraction Devices for Knee Joint Distraction.

Aim and objectiveThis study was designed to test and compare the mechanical performance of the biplanar ArthroSave KneeReviver and a circular frame construct with the intended use of providing a mechanically favourable environment for cartilage regeneration across a knee joint.Materials and methodsThree similar constructs of the two devices were applied to biomechanical testing sawbones, with the knee distracted by 8 mm. The constructs were vertically loaded to 800 N in an Instron testing machine at 20 mm/minute. Tests were conducted in neutral hip flexion and at 12° of hip flexion and extension, to mimic leg position in gait. Displacement measurements were taken from the Instron machine, and three-dimensional joint motion was recorded using an Optotrak Certus motion capture system.ResultsOverall axial rigidity was similar between the two devices (circular frame, 81.6 N/mm ± 5.9; and KneeReviver, 79.5 N/mm ± 25.1 with hip neutral) and similar in different hip positions. At the point of joint contact, the overall rigidity of the circular frame increased significantly more than the KneeReviver (491 N/mm ± 27 and 93 N/mm ± 32, respectively, p <0.001). There was more variability between models in the KneeReviver. There was more off-axis motion in the KneeReviver, mainly due to increasing knee flexion on loading. This was exacerbated with the hip in flexion and extension but remained small, with the maximal off-axis displacement being 7 mm/3°.ConclusionThe circular frame provides a similar mechanical environment to the novel KneeReviver device, for which most clinical data are available. These findings suggest that both devices appear a viable option for knee joint distraction (KJD). Further clinical data will help inform mode of application.Clinical significanceKJD is a relatively novel technique for use in osteoarthritis (OA), and it remains unclear which distraction devices provide appropriate mechanics. Our testing gives evidence to support either option for further use.How to cite this articleChowdhury JMY, Lineham B, Pallett M, et al. Comparison of Mechanical Performance between Circular Frames and Biplanar Distraction Devices for Knee Joint Distraction. Strategies Trauma Limb Reconstr 2021;16(2):71–77.

Cartilage Repair Activity during Joint-Preserving Treatment May Be Accompanied by Osteophyte Formation

Knee joint distraction (KJD) treatment has shown cartilage repair and clinical improvement in patients with osteoarthritis, as has high tibial osteotomy (HTO). Following KJD, TGFβ-1 and IL-6 were increased in synovial fluid (SF), factors related to cartilage regeneration, but also to osteophyte formation. As such, osteophyte formation after both joint-preserving treatments was studied. Radiographic osteophyte size was measured before, one year, and two years after treatment. Changes were compared with natural progression in patients from the CHECK cohort before undergoing total knee arthroplasty. An additional KJD cohort underwent SF aspiration, and one-year Altman osteophyte score changes were compared to SF-marker changes during treatment. After two years, both KJD (n = 58) and HTO (n = 38) patients showed an increase in osteophyte size (+6.2 mm2 and +7.0 mm2 resp.; both p &lt; 0.004), with no significant differences between treatments (p = 0.592). Untreated CHECK patients (n = 44) did not show significant two-year changes (+2.1 mm2; p = 0.207) and showed significant differences with KJD and HTO (both p &lt; 0.044). In SF aspiration patients (n = 17), there were significant differences in TGFβ-1 changes (p = 0.044), but not IL-6 (p = 0.898), between patients with a decrease, no change, or increase in osteophyte Altman score. Since KJD and HTO showed joint space widening and clinical improvement accompanied by osteophyte formation, increased osteophytosis after joint-preserving treatments may be a bystander effect of cartilage repair activity related to intra-articular factors like TGFβ-1 and raises questions regarding osteophyte formation as solely characteristic of the joint degenerative process.

Knee joint distraction results in MRI cartilage thickness increase up to 10 years after treatment.

ObjectivesKnee joint distraction (KJD) has been shown to result in long-term clinical improvement and short-term cartilage restoration in young OA patients. The objective of the current study was to evaluate MRI cartilage thickness up to 10 years after KJD treatment, using a 3D surface-based approach.MethodsTwenty end-stage knee OA patients were treated with KJD. MRI scans (1.5 T) were performed before and at 1, 2, 5, 7, and 10 years after treatment. Tibia and femur cartilage segmentation and registration to a canonical surface were performed semi-automatically. Statistical parametric mapping with linear mixed models was used to analyse whole-joint changes. The influence of baseline patient characteristics was analysed with statistical parametric mapping using linear regression. Relevant weight-bearing parts of the femur were selected to obtain the average cartilage thickness in the femur and tibia of the most- (MAC) and least-affected compartment. These compartmental changes over time were analysed using repeated measures ANOVA; missing data was imputed. In all cases, P <0.05 was considered statistically significant.ResultsOne and 2 years post-treatment, cartilage in the MAC weight-bearing region was significantly thicker than pre-treatment, gradually thinning after 5 years, but still increased at 10 years post-treatment. Long-term results showed that areas in the least-affected compartment were significantly thicker than pre-treatment. Male sex and more severe OA at baseline somewhat predicted shorter-term benefit (P >0.05). Compartmental analyses showed significant short- and long-term thickness increase in the tibia and femur MAC (all P <0.05). ConclusionKJD results in significant short- and long-term cartilage regeneration, up to 10 years post-treatment.Trial registrationNetherlands Trial Register, https://www.trialregister.nl, NL419.