Risk of Arthroplasty in Patients with Subchondral Insufficiency Fractures of the Knee: A Matched Study of the Implantable Shock Absorber using a Validated Predictive Model.

Subchondral insufficiency fractures of the knee (SIFK) can result in high rates of osteoarthritis and arthroplasty. The implantable shock absorber (ISA) implant is a titanium and polycarbonate urethane device which reduces the load on the medial compartment of the knee by acting as an extra-articular load absorber while preserving the joint itself. The purpose of this study was to evaluate whether partially unloading the knee with the ISA altered the likelihood of progression to arthroplasty utilizing a validated predictive risk model (SIFK score). A retrospective case-control (2:1) study was performed on patients with SIFK without any previous surgery and on those implanted with the ISA with the primary outcome being progression to arthroplasty compared with nonoperative treatment at 2 years. Baseline and final radiographs, as well as magnetic resonance imagings, were reviewed for the evaluation of meniscus or ligament injuries, insufficiency fractures, and subchondral edema. Patients from a prospective study were matched using the exact SIFK Score, a validated predictive score for progression to arthroplasty in patients with SIFK, to those who received the ISA implant. Kaplan-Meier analysis was conducted to assess survival. A total of 57 patients (38 controls:19 ISA) with a mean age of 60.6 years and 54% female were included. The SIFK score was matched exactly between cases and controls for all patients. The 2-year survival rate of 100% for the ISA group was significantly higher than the corresponding rate of 61% for the control group (p < 0.01). In ISA, 0% of the patients converted to arthroplasty at 2 years, and 5% (one patient) had hardware removal at 1 year. When stratified by risk, the ISA group did not have a significantly higher survival compared with low-risk (p = 0.3) or medium-risk (p = 0.2) controls, though it had a significantly higher survival for high-risk groups at 2 years (100 vs. 15%, p < 0.01). SIFK of the medial knee can lead to significant functional limitation and high rates of conversion to arthroplasty. Implants such as the ISA have the potential to alter the progression to arthroplasty in these patients, especially those at high risk.

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.

Single-Stage Autologous Chondrocyte-Based Treatment for the Repair of Knee Cartilage Lesions: Two-Year Follow-up of a Prospective Single-Arm Multicenter Study.

BACKGROUND: There is an unmet need for a single-stage cartilage repair treatment that is cost-effective and chondrocyte-based. PURPOSE: To evaluate the safety and preliminary efficacy of autologous freshly isolated primary chondrocytes and bone marrow mononucleated cells (MNCs) seeded into a PolyActive scaffold in patients with symptomatic cartilage lesions of the knee. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 40 patients with symptomatic knee cartilage lesions were treated with freshly isolated autologous chondrocytes combined with bone marrow MNCs delivered in a biodegradable load-bearing scaffold. The treatment requires only 1 surgical intervention and is potentially a cost-effective alternative to autologous chondrocyte implantation. The primary chondrocytes and bone marrow MNCs were isolated, washed, counted, mixed, and seeded into a load-bearing scaffold in the operating room. Patients were followed up at 3, 6, 12, 18, and 24 months. Primary endpoints were treatment-related adverse events up to 3 months, adverse implant effects between 3 and 24 months, and the implant success rate at 3 months as measured by lesion filling. RESULTS: Successful lesion filling (≥67% on magnetic resonance imaging) was found in 40 patients at 3 months and in 32 of the 32 patients analyzed at 24 months. Significant improvement over baseline was found for visual analog scale for pain from 3 months onward; Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain and KOOS-Activities of Daily Living from 6 months onward; for KOOS-Symptoms and Stiffness, KOOS-Quality of Life and International Knee Documentation Committee from 12 months onward; and for KOOS-Sport and Recreation from 18 months onward. Hyaline-like repair tissue was found in 22 of 31 patients available for biopsy. Arthralgia and joint effusion were the most common adverse events. Scaffold delamination and adhesions led to removal of the implant in 2 patients. CONCLUSION: The treatment of knee cartilage lesions with autologous primary chondrocytes and bone marrow MNCs, both isolated and seeded into a load-bearing PolyActive scaffold within a single surgical intervention, is safe and clinically effective. Good lesion fill and sustained clinically important and statistically significant improvement in all patient-reported outcome scores were found throughout the 24-month study. Hyaline-like cartilage was observed on biopsy specimen in at least 22 of the 40 patients. REGISTRATION: NCT01041885 (ClinicalTrials.gov identifier).

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).

Treatment options for the symptomatic post-meniscectomy knee.

PURPOSE: To provide a current review on the evidence for management of the symptomatic meniscus-deficient knee. METHODS: A literature review was performed detailing the natural history and origin of symptoms in a meniscus-deficient knee, in addition to strategies for non-surgical management, meniscus scaffolds, meniscus allograft transplantation (MAT), isolated cartilage repair, unloading osteotomies, meniscus prosthesis, and joint replacements which were revealed as treatment possibilities. RESULTS: Meniscus deficiency was recognized to lead to an early onset knee osteoarthritis (OA). A subset of patients develop post-meniscectomy syndrome: dull and nagging pain after a short pain-free interval subsequently to meniscectomy, which can be accompanied by transient effusions. Evidence for non-surgical management of post-meniscectomy knee pain is lacking. Two available meniscus scaffolds, indicated for symptomatic segmental meniscus deficiency, show pain relief at mid-term follow-up, and effect on joint preservation is unclear. MAT represents a durable solution for sub/total meniscus deficiency (80% survival at 10 years), but it is still considered a temporary solution for post-meniscectomy pain. MAT may also reduce the progression of OA. Isolated cartilage repair without a meniscus reconstruction is commonly performed, but better results were reported with preserved or reconstructed menisci. Osteotomies are used in the combination of misaligned knee and meniscus reconstruction or as pain solution for irreversible unilateral knee structural changes following a meniscectomy. Polycarbonate-urethane medial meniscus prosthesis is currently undergoing clinical trial. Joint replacements should be limited to later stages of post-meniscectomy OA. CONCLUSIONS: Post-meniscectomy pain syndrome and post-meniscectomy knee OA are common findings after meniscus resection. Short-term pain relief is provided by non-surgical management, mid-term pain relief by meniscus scaffolds, and long-term relief by MAT, though each has differing indications. In later stages, osteotomies and joint replacements are indicated. LEVEL OF EVIDENCE: IV.

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.

Treating Early Knee Osteoarthritis with the Atlas® Unicompartmental Knee System in a 26-Year-Old Ex-Professional Basketball Player: A Case Study.

Knee osteoarthritis (OA) is a leading cause of disability among adults. Within the affected population, there exists a group of patients who have exhausted conservative treatment options and yet are not ideal candidates for current surgical treatments due to young age, early disease severity, or neutral mechanical knee alignment. For these patients, a new potential treatment option may be considered. We present an interesting case report of a young, ex-professional athlete treated with a minimally invasive load-altering implant (Atlas System) whose young age (26 years), disease status (tibiofemoral kissing lesions), and neutral mechanical limb alignment eliminated all traditional surgical treatment options such as high tibial osteotomy or arthroplasty. At 6 months after surgery, our patient demonstrated positive outcomes improvement in pain, function, and quality of life and had returned to high-impact athletic activity without symptoms. These initial results are promising, and longer follow-up data on the treatment will be necessary.

Short-term safety and efficacy of a novel high tibial osteotomy system: a case controlled study.

PURPOSE: To evaluate the safety and efficacy of the novel iBalance Medial Opening Wedge High Tibial Osteotomy (HTO) system in executing lower limb realignment in patients with symptomatic varus gonarthrosis. METHODS: A multicentre case series of iBalance medial opening wedge HTO was compared to an historic case-matched control series of HTO's performed using another implant. Subjects were prospectively observed at 3, 6 and 12 months after surgery. Primary endpoints included the reporting of adverse events, weight-bearing status without pain and radiographic evidence of bony union. Secondary endpoints included maintenance of osteotomy correction angle, patient reported outcome (KOOS and SF-36) and gait analysis. RESULTS: Thirty-two consecutive patients were included in the iBalance group (mean age 49.7, 30-67; M:F, 20:12), paired with 32 control subjects (49.8, 35-66; 21:11). Three patients (9.4%) in the iBalance group experienced a complication requiring intervention versus one patient (3.1%) in the control group. No statistically significant differences were seen between groups in terms of time to weight bearing, radiographic union, implant stability or patient reported outcome. Gait analysis revealed a statistically significant reduction in knee external adduction moment (P < 0.001). CONCLUSIONS: The iBalance medial opening wedge HTO system has been shown to be a safe, novel implant for use in proximal tibial osteotomy. This study shows that the iBalance medial opening wedge HTO system has an equivalent short-term safety and efficacy profile to the 2nd generation Puddu system.