Patient-specific metal implants for focal chondral and osteochondral lesions in the knee; excellent clinical results at 2 years

Personalized Resurfacing for Osteochondral Lesions of the Talus

Osteochondral lesions of the talus (OLTs) are the most common cause of chronic deep ankle pain. Joint-preserving surgeries include bone marrow stimulating, chondral transporting, and cellular-based procedures. Each procedure has its advantages and disadvantages. For that reason, a focal metallic inlay was developed as a bridge between biologics and conventional joint arthroplasty. Despite promising initial results, prefabricated implants are associated with unpredictable results. This article describes a novel customized patient-specific metal inlay as a treatment option for OLTs.

Treatment of knee cartilage lesions in 2024: From hyaluronic acid to regenerative medicine

Abstract

Intact articular cartilage plays a vital role in joint homeostasis. Local cartilage repairs, where defects in the cartilage matrix are filled in and sealed to congruity, are therefore important treatments to restore a joint equilibrium. The base for all cartilage repairs is the cells; either chondrocytes or chondrogeneic cells from bone, synovia and fat tissue. The surgical options include bone marrow stimulation techniques alone or augmented with scaffolds, chondrogeneic cell implantations and osteochondral auto- or allografts. The current trend is to choose one-stage procedures being easier to use from a regulatory point of view. This narrative review provides an overview of the current nonoperative and surgical options available for the repair of various cartilage lesions.

Level of Evidence

Level IV.

Evaluation of rabbit adipose derived stem cells fate in perfused multilayered silk fibroin composite scaffold for Osteochondral repair

Development of osteochondral tissue engineering approaches using scaffolds seeded with stem cells in association with mechanical stimulations has been recently considered as a promising technique for the repair of this tissue. In this study, an integrated and biomimetic trilayered silk fibroin (SF) scaffold containing SF nanofibers in each layer was fabricated. The osteogenesis and chondrogenesis of stem cells seeded on the fabricated scaffolds were investigated under a perfusion flow. 3-Dimethylthiazol-2,5-diphenyltetrazolium bromide assay showed that the perfusion flow significantly enhanced cell viability and proliferation. Analysis of gene expression by stem cells revealed that perfusion flow had significantly upregulated the expression of osteogenic and chondrogenic genes in the bone and cartilage layers and downregulated the hypertrophic gene expression in the intermediate layer of the scaffold. In conclusion, applying flow perfusion on the prepared integrated trilayered SF-based scaffold can support osteogenic and chondrogenic differentiation for repairing osteochondral defects.

Surgical Treatment of Focal Chondral Lesions of the Knee in the Military Population: Current and Future Therapies

INTRODUCTION

Chondral and osteochondral defects of the knee are common injuries in the military population that have a significant impact on readiness. Definitive treatment of these injuries is challenging since cartilage has a limited capacity for self-repair and regeneration. Management is particularly challenging in military patients who maintain a higher level of activity similar to athletes. Existing surgical techniques have variable results and often long recovery times, sparking the development of several new innovative technologies to return service members back to duty more quickly and effectively after cartilage injury. The purpose of this article is to review the current and future surgical treatments for chondral and osteochondral knee lesions and their relevance in managing these injuries in the military.

METHODS

In this review article, we describe the current treatments for chondral and osteochondral defects of the knee, reporting on outcomes in military populations. We explore emerging treatment modalities for cartilage defects, reporting innovations, stage of research, and current data. Published results of each treatment option in military populations are reviewed throughout the article.

RESULTS

This review includes 12 treatments for chondral lesions. Of these therapies, four are considered synthetic and the remaining are considered regenerative solutions. Regenerative therapies tend to perform better in younger, healthier populations with robust healing capacity. Success of treatment depends on lesions and patient characteristics. Nearly all modalities currently available in the USA were successful in improving patients from presurgical function in the short (<6 months) term, but the long-term efficacy is still challenged. Upcoming technologies show promising results in clinical and animal studies that may provide alternative options desirable for the military population.

CONCLUSIONS

The current treatment options for cartilage lesions are not entirely satisfactory, usually with long recovery times and mixed results. An ideal therapy would be a single procedure that possesses the ability to enable a quick return to activity and duty, alleviate pain, provide long-term durability, and disrupt the progression of osteoarthritis. Evolving technologies for cartilage lesions are expanding beyond currently available techniques that may revolutionize the future of cartilage repair.

Fostering Excellence in Knee Arthroplasty: Developing Optimal Patient Care Pathways and Inspiring Knowledge Transfer of Advanced Surgical Techniques

Osteoarthritis of the knee is common. Early sports trauma or cartilage defects are risk factors for osteoarthritis. If conservative treatment fails, partial or total joint replacement is often performed. A joint replacement aims to restore physiological biomechanics and the quality of life of affected patients. Total knee arthroplasty is one of the most performed surgeries in musculoskeletal medicine. Several developments have taken place over the last decades that have truly altered the way we look at knee arthroplasty today. Some of the fascinating aspects will be presented and discussed in the present narrative review.

Treatment of Articular Cartilage Defects: A Descriptive Analysis of Clinical Characteristics and Global Trends Reported from 2001 to 2020

PURPOSE

To evaluate the clinical characteristics and global trends in the surgical treatment of articular cartilage defects.

METHODS

Studies in English published between January 1, 2001 and December 31, 2020 were retrieved from MEDLINE, WOS, INSPEC, SCIELO, KJD, and RSCI on the "Web of Science." Patient data were extracted, including age, sex, defect location and laterality, duration of follow-up and symptoms, and body mass index (BMI). Data were further stratified according to the surgical method, lesion location, procedural type and geographical area, and time period. A comparative analysis was performed.

RESULTS

Overall, 443 studies involving 26,854 patients (mean age, 35.25 years; men, 60.5%) were included. The mean lesion size and patient BMI were 3.51 cm2 and 25.61 kg/m2, respectively. Cartilage defects at the knees, talus, and hips affected 20,850 (77.64%), 3,983 (14.83%), and 1,425 (5.31%) patients, respectively. The numbers of patients who underwent autologous chondrocyte implantation, arthroscopic debridement/chondroplasty, osteochondral allograft (OCA), osteochondral autologous transplantation, and microfracture were 7,114 (26.49%), 5,056 (18.83%), 3,942 (14.68%), 3,766 (14.02%), and 2,835 (10.56%), respectively. European patients were the most numerous and youngest. North American patients had the largest defects. The number of patients increased from 305 in 2001 to 3,017 in 2020. In the last 5 years, the frequency of OCAs showed a greatly increasing trend.

CONCLUSION

Clinical characteristics and global trends in the surgical treatment of articular cartilage defects were revealed. The choice of operation should be based on the patient characteristics and defect location, size, and shape, as well as the patient's preference.

2-year results of middle-aged patients with two-compartment cartilage lesions in one knee treated with two patient specific metal implants

PURPOSE

Focal chondral lesions of the femur are currently treated with biological repair or arthroplasty. However, some patients are not suitable for either one due to lesion size, age, or prior biological treatment attempts. While singular patient-specific focal mini metal implants already showed good results, the outcomes of bicompartmental implantation of these implants have not been discussed in the literature yet. This study aims to evaluate clinical outcomes of patients who underwent bicompartmental implantation of two patient-specific implants.

METHODS

This prospective, non-randomized, non-comparative pilot study evaluates results up to two years after bicompartmental implantation of two implants (Episealer Implant, Episurf, Stockholm, Sweden). A damage report is compiled using a special MRI program and patient specific implants are manufactured, including 3D-printed surgical instruments to provide exact placement of the implant. The patients were assessed repeatedly using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Visual Analogue Scale (VAS) for pain during the follow-up.

RESULTS

The scores were evaluated three, 12, and 24 months after surgery and showed good results. The median in both scores improved from 37.7 for the KOOS5 preoperatively to 69.1 after 24 months and from 69 for the VAS for pain preoperatively to 9 after 24 months.

CONCLUSION

Overall, for the small study group presented, the early results are promising. With noticeable improvement in KOOS and VAS for pain after two years, patient specific implants appear to become relevant in future standardized treatment of femoral chondral lesions. Especially with bicompartmental implantation, full arthroplasty can be delayed even further.

LEVEL OF EVIDENCE

IV.

High degree of consensus amongst an expert panel regarding focal resurfacing of chondral and osteochondral lesions of the femur with mini-implants

INTRODUCTION

The rationale for the use of mini-implants for partial resurfacing in the treatment of femoral chondral and osteochondral lesions is still under debate. The evidence supporting best practise guidelines is based on studies with low-level evidence. A consensus group of experts was convened to collaboratively advance towards consensus opinions regarding the best available evidence. The purpose of this article is to report the resulting consensus statements.

METHODS

Twenty-five experts participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted via an online survey of two rounds, for initial agreement and comments on the proposed statements. An in-person meeting between the panellists was organised during the 2022 ESSKA congress to further discuss and debate each of the statements. A final agreement was made via a final online survey a few days later. The strength of consensus was characterised as: consensus, 51-74% agreement; strong consensus, 75-99% agreement; unanimous, 100% agreement.

RESULTS

Statements were developed in the fields of patient assessment and indications, surgical considerations and postoperative care. Between the 25 statements that were discussed by this working group, 18 achieved unanimous, whilst 7 strong consensus.

CONCLUSION

The consensus statements, derived from experts in the field, represent guidelines to assist clinicians in decision-making for the appropriate use of mini-implants for partial resurfacing in the treatment of femoral chondral and osteochondral lesions.

LEVEL OF EVIDENCE

Level V.

Low local curvature index and history of previous surgery are risk factors for revision in focal metallic inlay implants

BACKGROUND

Focal chondral defects are debilitating lesions with poor healing potential. Focal metallic inlay implants were developed as a salvage procedure, whose reoperation causes and risk factors for revision are still debatable. The aim of this study is to analyze the local subchondral curvature matching of focal metallic inlay implants and its effects on survival and clinical results.

METHODS

Patients operated with a knee focal metallic inlay resurfacing implant between 2014 and 2017 were eligible. Surgery was indicated for painful, focal, full-thickness cartilage lesions that had failed alternative treatments. Inclusion criteria were patients treated for a lesion ≤ 5 cm2 in the femoral condyle, aged 40-65 years, with complete surgical records and a knee CT scan. The curvature index (Kindex) was calculated as the ratio of the mean curvature of the implant (K1) to the mean curvature of the subchondral bone (K2).

RESULTS

Sixty-nine patients were included, of which 60.9% were female. Mean age was 54.8 ± 6.0. Seven patients (10.1%) underwent revision surgery. When adjusted for age and sex, lesion size was not significantly correlated to revision in a multivariate regression model, while previous surgery and smaller K index were. A positive history for previous surgery was significantly correlated with worse clinical outcomes in surviving patients.

CONCLUSION

A positive history of previous knee surgery and a low local curvature index are risk factors for revision after focal metallic inlay implant resurfacing. Patients with a history of knee surgery should be counseled on the advantages and disadvantages before undergoing a focal resurfacing procedure.

Individualized metal implants for focal cartilage lesions in the knee can be cost-effective: A simulation on 47-year-old in a Swedish setting

OBJECTIVES

In the aging population, the knee is the joint most commonly causing impaired function and incapacity. While definite treatment by prosthetic replacement is often performed late, symptomatic knee cartilage lesions cause much suffering also in younger ages. Early intervention could, therefore, be instituted at an early stage to the benefit of both patients and society. Small, metal surface, resurfacing implants have been tested with promising results. A system that features patient-specific implants and surgical instruments shows good clinical results and favorable survival rates. This study aims to assess the cost utility of this metal device compared with microfracture (MFX), being the standard procedure in Sweden.

METHODS

We constructed a simulation model in Excel. In the model, a cohort of 47-year-old patients (which is the mean age of patients treated with the metal implant) with symptomatic knee cartilage lesions received either MFX or metal implantation. Outcomes for the cohort were simulated over 40 years, such as in a previously published model based on MFX, and sensitivity analyses (deterministic and probabilistic) of the results were undertaken. Data on transition probabilities, costs, and quality of life were taken from clinical data, published literature, and official price lists. Only direct medical costs were included.

RESULTS

Results from the analysis showed that the metal device is a cost-effective treatment strategy compared with MFX. The incremental cost-effectiveness ratio (ICER) reached acceptable levels at ∼5 years postoperatively. Over the full-time horizon of 40 years, the metal device was cost saving with concomitant gains in quality-adjusted life years (QALYs), translating to a dominant treatment strategy. Results were robust according to sensitivity analysis with the initial success rate of up to three years for both metal and MFX having the largest impact.

CONCLUSIONS

A metal implant may be a cost-effective treatment alternative for patients in their 40's when compared to MFX in a Swedish setting.

LEVEL OF EVIDENCE

5 [1].

Osteochondral Lesions of Ankle and Knee. Will Future Treatments Really Be Represented by Custom-Made Metal Implants?

Knee and ankle osteochondral lesions are structural defects of the cartilaginous surface and underlying subchondral bone which still represent a daily challenge for the orthopedic surgeon [...]

Good subjective outcome and low risk of revision surgery with a novel customized metal implant for focal femoral chondral lesions at a follow-up after a minimum of 5 years

BACKGROUND AND PURPOSE

Patients with focal cartilage lesions experience functional impairment. Results for biological treatments in the middle-aged patient is poor. Previous studies with focal prosthetic inlay resurfacing have shown a higher risk of conversion to total knee replacement at mid-term follow-up. A novel customized implant (Episealer, Episurf, Stockholm, Sweden) has been proposed to improve implant positioning and survival. The primary objective was to assess subjective-, objective function and implant survival at a minimum of five years after surgery.

MATERIALS AND METHODS

The inclusion criteria were patients aged 30-65 years with symptomatic focal chondral defects in the medial femoral condyle, International Cartilage Research Society grade 3 or 4 and failed conservative or surgical treatment. Minimum follow-up of 5 years. Clinical and radiologic assessments were made. Patient-reported outcome measurements at the latest follow-up were compared with the baseline data for the Knee injury and Osteoarthritis Outcome Score (KOOS), the EuroQoL (EQ-5D), the Tegner Activity Scale and a Visual Analog Scale of pain (VAS 0-10).

RESULTS

Ten patients with the mean follow-up period of 75 months (60-86 months, SD 10) were included. Signs of osteoarthritis were seen in one patient (Ahlbäck 1). No cases with revision to knee replacement. VAS for pain and KOOS showed improvements that reached significance for VAS (p ≤ 0.001) and the KOOS subscores Pain (p = 0.01), ADL (p = 0.003), Sport and Recreation (p = 0.024) and Quality of Life (p = 0.003).

CONCLUSION

A good subjective outcome, a low risk of progression to degenerative changes and the need for subsequent surgery were seen at the mid-term follow-up with this customized focal knee-resurfacing implant.

LEVEL OF EVIDENCE

Prospective case series, level 4.

Ultrasound-Based Quantification of Cartilage Damage After In Vivo Articulation With Metal Implants

OBJECTIVE

This study aims to evaluate the applicability of the ultrasound roughness index (URI) for quantitative assessment of cartilage quality ex vivo (post-mortem), after 6 months of in vivo articulation with a Focal Knee Resurfacing Implant (FKRI).

DESIGN

Goats received a metal FKRI (n = 8) or sham surgery (n = 8) in the medial femoral condyles. After 6 months animals were sacrificed, tibial plateaus were stained with Indian ink, and macroscopic scoring of the plateaus was performed based on the ink staining. The URI was calculated from high-frequency ultrasound images at several sections, covering both areas that articulated with the implant and non-articulating areas. Cartilage quality at the most damaged medial location was evaluated with a Modified Mankin Score (MMS).

RESULTS

The URI was significantly higher in the FKRI-articulating than in the sham plateaus at medial articulating sections, but not at sections that were not in direct contact with the implant, for example, under the meniscus. The mean macroscopic score and MMS were significantly higher in the FKRI-articulating group than in the sham group (P=0.035, P<0.001, respectively). Correlation coefficients between URI and macroscopic score were significant in medial areas that articulated with the implant. A significant correlation between URI and MMS was found at the most damaged medial location (ρ=0.72,P=0.0024).

CONCLUSIONS

This study demonstrates the potential of URI to evaluate cartilage roughness and altered surface morphology after in vivo articulation with a metal FKRI, rendering it a promising future tool for quantitative follow-up assessment of cartilage quality.

Eighty Percent Survival of Resurfacing Implants in the Knee After 10 Years: A Nationwide Cohort Study on 379 Procedures from the Danish Knee Arthroplasty Registry

OBJECTIVE

Focal cartilage injuries are debilitating and difficult to treat. Biological cartilage repair procedures are used for patients younger than 40 years, and knee arthroplasties are generally reserved for patients older than 60 years. Resurfacing implants are well suited for patients in this treatment gap. The objective was to investigate the 10-year survival of resurfacing implants in the Danish Knee Arthroplasty Registry.

DESIGN

In this retrospective cohort study, patients treated with resurfacing implants were followed longitudinally in the Danish Knee Arthroplasty Registry from 1997 to 2020. The primary endpoint was revision surgery. The survival of the resurfacing implants was analyzed by Kaplan-Meier method.

RESULTS

A total of 379 resurfacing implant procedures were retrieved from the Danish Knee Arthroplasty Registry. The mean age and weight of patients were 50 years (SD = 11) and 84 kg (SD = 17), respectively. The indications for surgery were as follows: secondary osteoarthritis (42%), primary osteoarthritis (32%), and osteochondral lesions (20%). Within the follow-up period, 70 (19%) of the implants were revised to arthroplasties. The 1-, 5-, and 10-year revision-free survival estimation was 0.95 (95% CI 0.93-0.97), 0.84 (95% CI 0.80-0.88), and 0.80 (95% CI 0.75-0.84), respectively. The median time to revision was 2 years.

CONCLUSION

The 10-year revision-free survival rate for resurfacing implants was 80%. Based on the revision rates, this treatment offers a viable alternative to biological cartilage repair methods in patients aged 40 to 60 years with focal cartilage pathology. Improved patient selection could further improve the implant survival rate. Further studies are needed to investigate this treatment method.

A Systematic Review of Focal Cartilage Defect Treatments in Middle-Aged Versus Younger Patients

Background:

Focal cartilage defects are often debilitating, possess limited potential for regeneration, are associated with increased risk of osteoarthritis, and are predictive for total knee arthroplasty. Cartilage repair studies typically focus on the outcome in younger patients, but a high proportion of treated patients are 40 to 60 years of age (ie, middle-aged). The reality of current clinical practice is that the ideal patient for cartilage repair is not the typical patient. Specific attention to cartilage repair outcomes in middle-aged patients is warranted.

Purpose:

To systematically review available literature on knee cartilage repair in middle-aged patients and include studies comparing results across different age groups.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic search was performed in EMBASE, MEDLINE, and the Cochrane Library database. Articles were screened for relevance and appraised for quality.

Results:

A total of 21 articles (mean Coleman Methodology Score, 64 points) were included. Two out of 3 bone marrow stimulation (BMS) studies, including 1 using the microfracture technique, revealed inferior clinical outcomes in middle-aged patients in comparison with younger patients. Nine cell-based studies were included showing inconsistent comparisons of results across age groups for autologous chondrocyte implantation (ACI). Bone marrow aspirate concentrate showed age-independent results at up to 8 years of follow-up. A negative effect of middle age was reported in 1 study for both ACI and BMS. Four out of 5 studies on bone-based resurfacing therapies (allografting and focal knee resurfacing implants [FKRIs]) showed age-independent results up to 5 years. One study in only middle-aged patients reported better clinical outcomes for FKRIs when compared with biological repairs.

Conclusion:

Included studies were heterogeneous and had low methodological quality. BMS in middle-aged patients seems to only result in short-term improvements. More research is warranted to elucidate the ameliorating effects of cell-based therapies on the aging joint homeostasis. Bone-based therapies seem to be relatively insensitive to aging and may potentially result in effective joint preservation. Age subanalyses in cohort studies, randomized clinical trials, and international registries should generate more evidence for the large but underrepresented (in terms of cartilage repair) middle-aged population in the literature.

Patient-specific resurfacing implant knee surgery in subjects with early osteoarthritis results in medial pivot and lateral femoral rollback during flexion: a retrospective pilot study

PURPOSE

Metallic resurfacing implants have been developed for the treatment of early, small, condylar and trochlear osteoarthritis (OA) lesions. They represent an option for patients who do not fulfill the criteria for unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA) or are too old for biological treatment. Although clinical evidence has been collected for different resurfacing types, the in vivo post-operative knee kinematics remain unknown. The present study aims to analyze the knee kinematics in subjects with patient-specific episealer implants. This study hypothesized that patient-specific resurfacing implants would lead to knee kinematics close to healthy knees, resulting in medial pivot and a high degree of femoral rollback during flexion.

METHODS

Retrospective study design. Fluoroscopic analysis during unloaded flexion-extension and loaded lunge was conducted at > 12 months post-surgery in ten episealer knees, and compared to ten healthy knees. Pre- and post-operative clinical data of the episealer knees were collected using a visual analog scale (VAS), the EQ 5d Health, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaires.

RESULTS

A consistent medial pivot was observed in both episealer and healthy knees. Non-significant differences were found in the unloaded (p = 0.15) and loaded (p = 0.51) activities. Although lateral rollback was observed in both groups, it was significantly higher for the episealer knees in both the unloaded (p = 0.02) and loaded (p = 0.01) activities. Coupled axial rotation was significantly higher in the unloaded (p = 0.001) but not in the loaded (p = 0.06) activity in the episealer knees. Improved scores were observed at 1-year post-surgery in the episealer subjects for the VAS (p = 0.001), KOOS (p = 0.001) and EQ Health (p = 0.004).

CONCLUSION

At 12 month follow-up, a clear physiological knee kinematics pattern of medial pivot, lateral femoral rollback and coupled axial external femoral rotation during flexion was observed in patients treated with an episealer resurfacing procedure. However, higher femoral rollback and axial external rotation in comparison to healthy knees was observed, suggesting possible post-operative muscle weakness and consequent insufficient stabilization at high flexion.

[Focal femoral resurfacing and unicompartmental knee replacement : Between osteotomy and total knee replacement]

Unicompartmental knee arthroplasty, especially for both femorotibial compartments of the knee, is an established partly joint-saving treatment option for osteoarthritis of the knee if the disease is limited to one compartment. Even smaller implants or resurfacing of the patellofemoral joint have been shown-in smaller patient collectives-to have the potential to yield good clinical results.

Patient-Specific Implants for Focal Cartilage Lesions in The Knee: Implant Survivorship Analysis up to Seven Years Post-Implantation

In the quest for increased surgical precision and improved joint kinematics, Computer-Assisted Orthopedic Surgery (CAOS) shows promising results for both total and partial joint replacement. In the knee, computer-assisted joint design can now be applied to the treatment of younger patients suffering pain and restriction of activity due to focal defects in their femoral articular cartilage. By taking MRI scans of the affected knee and digitally segmenting these scans, we can identify and map focal defects in cartilage and bone. Metallic implants matched to the defect can be fabricated, and guide instrumentation to ensure proper implant alignment and depth of recession in the surrounding cartilage can be designed from segmented MRI scans. Beginning in 2012, a series of 682 patient-specific implants were designed based on MRI analysis of femoral cartilage focal defects, and implanted in 612 knees. A Kaplan-Meier analysis found a cumulative survivorship of 96% at 7-year follow-up from the first implantation. Fourteen (2.3%) of these implants required revision due to disease progression, incorrect implant positioning, and inadequate lesion coverage at the time of surgery. These survivorship data compare favorably with all other modes of treatment for femoral focal cartilage lesions and support the use of patient-specific implants designed from segmented MRI scans in these cases.