Unloading the osteoarthritic knee with a novel implant system

Longitudinal Relationship Between Tibiofemoral Contact Stress at Baseline and Worsening of Knee Pain Over 84 Months in the Multicenter Osteoarthritis Study

OBJECTIVE

The aim of the study was to determine whether tibiofemoral contact stress predicts risk for worsening knee pain over 84 ms in adults aged 50-79 yrs with or at elevated risk for knee osteoarthritis.

DESIGN

Baseline tibiofemoral contact stress was estimated using discrete element analysis. Other baseline measures included weight, height, hip-knee-ankle alignment, Kellgren-Lawrence grade, and Western Ontario and McMaster Universities Osteoarthritis Index pain subscale. Logistic regression models assessed the association between baseline contact stress and 84-mo worsening of Western Ontario and McMaster Universities Osteoarthritis Index pain subscale.

RESULTS

Data from the dominant knee (72.6% Kellgren-Lawrence grade 0/1 and 27.4% Kellgren-Lawrence grade ≥ 2) of 208 participants (64.4% female, mean ± SD body mass index = 29.6 ± 5.1 kg/m 2 ) were analyzed. Baseline mean and peak contact stress were 3.3 ± 0.9 and 9.4 ± 4.3 MPa, respectively. Forty-seven knees met the criterion for worsening pain. The highest tertiles in comparison with the lowest tertiles of mean (odds ratio [95% confidence interval] = 2.47 [1.03-5.95], P = 0.04) and peak (2.49 [1.03-5.98], P = 0.04) contact stress were associated with worsening pain at 84 mos, after adjustment for age, sex, race, clinic site, and baseline pain. Post hoc sensitivity analyses including adjustment for body mass index and hip-knee-ankle alignment attenuated the effect.

CONCLUSIONS

These findings suggest that elevated tibiofemoral contact stress can predict the development of worsening of knee pain.

Matrix metalloproteinase-13, NF-κB p65 and interleukin-1β are associated with the severity of knee osteoarthritis

Knee osteoarthritis (KOA) is a prevalent disease, especially in the elderly. The present study examined the expression of matrix metalloproteinase-13 (MMP-13), NF-κBp65 and interleukin (IL)-lβ in the synovial tissues of KOA patients and the role of MMP-13 and the NF-κBp65 signalling pathway in KOA pathogenesis. A total of 100 KOA patients were enrolled in our hospital from December 2015 to December 2017 and were classified into either a mild KOA group (Outerbridge grade 1 and 2) or a severe KOA group (Outerbridge grade 3 and 4). Non-OA patients were included as controls. Synovial tissues from patients in both groups were collected for detection of the mRNA and protein expression of MMP-13, NF-κBp65 and IL-lβ. Synovial tissue slices were subjected to haematoxylin and eosin staining and immunohistochemistry (SP method). Cartilage tissues were observed under a light microscope after Safranin O-fast green staining. Reverse transcription-quantitative PCR and western blot analyses demonstrated that the expression of MMP-13, NF-κBp65 and IL-lβ in the mild and severe groups were substantially upregulated compared with the control group (all P<0.05). A positive correlation between MMP-13 and NF-κBp65 expression in the KOA synovial tissues was identified (P<0.05). Immunohistochemistry revealed that the expression of MMP-13 and NF-κBp65 was related to the severity of KOA (MMP-13: severe, 92.54%; moderate, 76.52%; control: 32.14%; and NF-κBp65: severe, 85.56%; moderate, 48.12%; control: 28.32%). This evidence indicated that the severity of KOA was related to MMP-13 and NF-κBp65 expression. The NF-κB signalling pathway may be activated during OA progression, which could upregulate the expression of MMP-13 and IL-1β and accelerate the deterioration of articular cartilage.

A Case Report of the Successful Conversion of One of the Longest Standing KineSpring Joint Unloading Systems

Introduction

We present the case of a successful conversion of a KineSpring joint unloading system to a total knee replacement. This is, to the best of our knowledge, the so far longest surviving implant in Germany that has been successfully converted.

Case Report

The patient is a 75-year-old woman who presented to clinic with problems of her left knee. She had a KineSpring joint unloading system implanted in March 2011 for severe medial osteoarthritis of her left knee that was unresponsive to maximal conservative treatment. After nearly 7 pain-free years, we successfully converted the KineSpring joint unloading system into a total knee replacement (Vega, Aesculap, Germany).

Conclusion

The KineSpring joint unloading system is possible treatment option for younger patients with mild-to-moderate osteoarthritis of the knee reluctant to total knee replacement, without compromising further surgical options.

Can UKA after KineSpring system failure be a viable option? A case report

Background and aim of the Work: The KineSpring System is an alternative treatment offered in selected symptomatic patients suffering from mild to moderate medial knee osteoarthritis (OA). This device reduces medial compartment loads in the OA knee without compromising the integrity of the lateral or patellofemoral knee compartments, maintaining the normal knee anatomy. Currently, papers about KineSpring System installation show promising results. The current authors describe a case of unicompartmental knee arthroplasty (UKA) employed to treat medial knee OA after Kinespring system failure. Methods: A 64-year old male patient presented to our hospital after failure of a Kinespring system implantation into his left knee at an external hospital, where the outcomes obtained were not satisfactory. The surgical options discussed with the patient were the TKA or medial UKA. A medial UKA was preferred by the patient. Results: One year from UKA, the patient complained of frequent joint effusions and weight bearing pain despite a good ROM without radiographic signs of implant loosening. Therefore, after two years we replaced UKA with total knee arthroplasty (TKA). Conclusions: Further experience is needed to provide reliable clinical data about the results of the UKA after KineSpring System discharge. (www.actabiomedica.it)

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.

Severe metallosis and elevated chromium in serum following implantation of the joint unloading implant system

In recent years, the minimally invasive joint-preserving implant system has been developed. The main goal of this device is to unload the medial knee compartment without affecting the lateral compartment. The current authors describe a severe metallosis and elevated chromium in serum following implantation of the joint unloading implant system of a 50-year-old male patient, presented to our hospital 3 years after implantation of a KineSpring System into his left knee due to unicompartmental medial osteoarthritis (OA) in an external hospital. Radiographs showed radiological signs for loosening of the screws in the tibia and a progressive OA on the medial and patellofemoral compartments. Revision surgery with removing of the unloading device was performed at our hospital. The intraoperative situs presented a severe metallosis around the device. Five days after revision surgery, the laboratory parameters revealed an elevated value for chromium in serum, while nickel and cobalt values in serum were normal. Reliable clinical data about the long-term results of the KineSpring System is desperately needed. Further studies are warranted to work out the effects of cobalt and chromium levels and further side effects following the implantation of the extra-articular absorber system.

Feasibility of the Atlas Unicompartmental Knee System Load Absorber in Improving Pain Relief and Function in Patients Needing Unloading of the Medial Compartment of the Knee: 1-Year Follow-Up of a Prospective, Multicenter, Single-Arm Pilot Study (PHANTOM High Flex Trial)

In young patients with medial knee osteoarthritis (OA), surgical intervention may not be desirable due to preferences to avoid bone cutting procedures, return to high activity levels, and prolong implant survival. The Atlas Knee System was designed to fill the gap between ineffective conservative treatments and invasive surgery. This single-arm study included 26 patients, aged 25 to 65 years, who completed 12 months of follow-up. All dimensions of the Knee injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Society Score significantly improved from baseline to 12 months. About 96.2% and 92.3% of patients experienced a ⩾20% improvement in their KOOS pain and WOMAC pain scores, respectively, at 12 months. This study highlights the potential benefit of a joint unloading device in the management of young patients with medial knee OA. The trial is still ongoing and another analysis is planned at 24 months.

Patient Preferences Regarding Surgical Interventions for Knee Osteoarthritis

Surgical interventions for knee osteoarthritis (OA) have markedly different procedure attributes and may have dramatic differences in patient desirability. A total of 323 patients with knee OA were included in a dual response, choice-based conjoint analysis to identify the relative preference of 9 different procedure attributes. A model was also developed to simulate how patients might respond if presented with the real-world knee OA procedures, based on conservative assumptions regarding their attributes. The “amount of cutting and removal of the existing bone” required for a procedure had the highest preference score, indicating that these patients considered it the most important attribute. More specifically, a procedure that requires the least amount of bone cutting or removal would be expected to be the most preferred surgical alternative. The model also suggested that patients who are younger and report the highest pain levels and greatest functional limitations would be more likely to opt for surgical intervention.

Use of the KineSpring system in the treatment of medial knee osteoarthritis: preliminary results

PURPOSE

the purpose of this study was to analyze our preliminary results obtained with the KineSpring system in patients suffering from medial compartment knee osteoarthritis (OA).

METHODS

between September 2012 and May 2014, 53 patients underwent treatment with the KineSpring system. Patient self-assessment was performed pre-operatively and at 3, 6 and 12 months postoperatively, and included the KOOS, Tegner activity score, Lysholm functional knee score, VAS knee pain score, and IKDC score. Device- and procedure-related adverse events were recorded.

RESULTS

mean KOOS subscales, except for the Sport/Recreation subscale at six months, improved over time. Mean WOMAC Pain and Function domains, Lysholm score, IKDC score and VAS knee pain score improved over the follow-up period and were significantly improved at 3, 6 and 12 months postoperatively compared to baseline. Mean Tegner score improved slightly over time. In 5 of the 53 (9.4%) patients re-operation was necessary. In 3 patients the device was removed due to infection (one case) or persistent knee pain (two cases). Surgical arthrolysis was performed in two patients.

CONCLUSIONS

in our preliminary experience, the KineSpring system gave good short-term clinical results.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Device-length changes and implant function following surgical implantation of the KineSpring in cadaver knees

Introduction

The KineSpring implant system has been shown to provide load reductions at the medial compartment of the knee, and has demonstrated clinical success in reducing pain and increasing function in patients with medial knee osteoarthritis. These results depend on the ability of the KineSpring to rotate, lengthen, and shorten to accommodate knee motions, and in response to knee position and loading.

Purpose

The present study was undertaken to determine length changes of the implanted KineSpring in response to a range of knee positions, external knee loads, and placements by different orthopedic surgeons.

Materials and methods

KineSpring system components were implanted in ten cadaver leg specimens by ten orthopedic surgeons, and absorber-length changes were measured under combined loading and in different positions of the knee.

Results and conclusion

Spring compression consistent with knee-load reduction, and device lengthening and shortening to accommodate knee loads and motions were seen. These confirm the functionality of the KineSpring when implanted medially to the knee.

Joint unloading implant modifies subchondral bone trabecular structure in medial knee osteoarthritis: 2-year outcomes of a pilot study using fractal signature analysis

Background

Knee osteoarthritis (OA) is largely attributable to chronic excessive and aberrant joint loading. The purpose of this pilot study was to quantify radiographic changes in subchondral bone after treatment with a minimally invasive joint unloading implant (KineSpring^® Knee Implant System).

Methods

Nine patients with unilateral medial knee OA resistant to nonsurgical therapy were treated with the KineSpring System and followed for 2 years. Main outcomes included Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, function, and stiffness subscores and independent core laboratory determinations of joint space width and fractal signature of the tibial cortex.

Results

WOMAC scores, on average, improved by 92% for pain, 91% for function, and 79% for stiffness over the 2-year follow-up period. Joint space width in the medial compartment of the treated knee significantly increased from 0.9 mm at baseline to 3.1 mm at 2 years; joint space width in the medial compartment of the untreated knee was unchanged. Fractal signatures of the vertically oriented trabeculae in the medial compartment decreased by 2.8% in the treated knee and increased by 2.1% in the untreated knee over 2 years. No statistically significant fractal signature changes were observed in the horizontally oriented trabeculae in the medial compartment or in the horizontal or vertical trabeculae of the lateral compartment in the treated knee.

Conclusion

Preliminary evidence suggests that the KineSpring System may modify knee OA disease progression by increasing joint space width and improving subchondral bone trabecular integrity, thereby reducing pain and improving joint function.

Post-traumatic knee osteoarthritis in the young patient: therapeutic dilemmas and emerging technologies

Traumatic knee injury is common in young adults and strongly contributes to premature development of knee osteoarthritis (OA). Post-traumatic knee OA poses a therapeutic dilemma to the physician, since no known therapy has an acceptable safety profile, effectively relieves joint pain, and enjoys reasonable patient acceptance. Consequently, these young patients will ultimately be faced with the decision to either undergo surgical intervention, despite prosthesis durability concerns, or to continue with ineffective nonsurgical treatment. Emerging therapies, such as biologics, disease-modifying drugs, partial joint resurfacings, and minimally invasive joint-unloading implants are currently being studied to fill this therapeutic void in the young patient with post-traumatic knee OA.

The KineSpring(®) Knee Implant System: an implantable joint-unloading prosthesis for treatment of medial knee osteoarthritis

Symptomatic medial compartment knee osteoarthritis (OA) is the leading cause of musculoskeletal pain and disability in adults. Therapies intended to unload the medial knee compartment have yielded unsatisfactory results due to low patient compliance with conservative treatments and high complication rates with surgical options. There is no widely available joint-unloading treatment for medial knee OA that offers clinically important symptom alleviation, low complication risk, and high patient acceptance. The KineSpring^® Knee Implant System (Moximed, Inc, Hayward, CA, USA) is a first-of-its-kind, implantable, extra-articular, extra-capsular prosthesis intended to alleviate knee OA-related symptoms by reducing medial knee compartment loading while overcoming the limitations of traditional joint-unloading therapies. Preclinical and clinical studies have demonstrated excellent prosthesis durability, substantial reductions in medial compartment and total joint loads, and clinically important improvements in OA-related pain and function. The purpose of this report is to describe the KineSpring System, including implant characteristics, principles of operation, indications for use, patient selection criteria, surgical technique, postoperative care, preclinical testing, and clinical experience. The KineSpring System has potential to bridge the gap between ineffective conservative treatments and irreversible surgical interventions for medial compartment knee OA.