A Comparison of the Outcomes for Cartilage Defects of the Knee Treated With Biologic Resurfacing Versus Focal Metallic Implants

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.

Focal resurfacing of the knee - A systematic review and meta-analysis

PURPOSE

In order to assess the published validity of focal resurfacing of the knee, a systematic review and meta-analysis were conducted to (i) evaluate revision rates and implant survival of focal resurfacing of the knee; (ii) explore surgical complications; and (iii) evaluate patient reported clinical outcome measures.

METHODS

PubMED, Cochrane Library and Medline databases were searched by 2 independent reviewers in February 2022 for prospective and retrospective cohort studies evaluating any of the following implant types: HemiCAP®, UniCAP®, Episealer® or BioBoly®. Data on incidence of revision, complications and various patient reported outcome measures, such as Knee Society Score (KSS) or Knee Injury and Osteoarthritis Outcome Score (KOOS) was sourced.

RESULTS

A total of 24 published studies were identified with a total of 1465 enrolled patients. A revision rate of 12.97% over a 5.9 year weighted mean follow-up period was observed across all implant types. However, in one series a Kaplan-Meir survival as high as 92.6% at a 10-year follow-up period was noted. A statistically significant improvement was documented across multiple subjective clinical outcomes scores, for example a mean 4.56 point improvement of the VAS (0-10) pain score. The Kellgren-Lawrence score was used to evaluate the radiological progression of osteoarthritis and showed a small significant reduction in all anatomical locations, hence not supporting the hypothesis that focal femoral implants can lead to the progression of osteoarthritis in the affected compartment. There was a low reported incidence of post-operative complications such as aseptic loosening or deep wound infection.

CONCLUSIONS

Focal femoral resurfacing appears to be a viable treatment option for focal symptomatic chondral lesions in patients beyond biological reconstruction, with low revision rates and high patient satisfaction especially at short and medium length follow-up.

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.

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.

Femoral condyle resurfacing using an inlay metal implant: low revision rate of 266 patients in a 5-10 years follow-up

PURPOSE

To assess the clinical outcome and survival of an inlay resurfacing prosthesis for focal femoral condyle chondral and osteochondral defects.

METHODS

Two hundred sixty-six patients (mean age, 38.25 years; range 25-56 years) with symptomatic femoral condyle chondral and osteochondral defects were reviewed. The mean follow-up period was 7.3 years (range 5-10 years). The medial femoral condyle was involved in 229 and the lateral condyle in 37 patients. Previous cartilage surgery was done in 235 patients. All patients were treated with focal femoral condyle resurfacing with the HemiCAP^® device. The preoperative and the last follow-up values of the Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), 36-item Short Form Survey (SF-36) and Visual Analogue Scale (VAS) were examined. Complications, reoperation rate and survival were analyzed.

RESULTS

At the last follow-up, all clinical score values showed significant improvement as compared with the corresponding preoperative values (p < 0.001). Age presented a negative correlation with KOOS (p = 0.03) and SF-36 improvement (p = 0.014). Kellgren-Lawrence grade influenced OKS (p = 0.036). BMI, gender, side, medial or lateral condyle and size did not affect the outcome. Patients who had previous biological cartilage procedures demonstrated better clinical improvement in comparison with those that did not have prior surgery (p < 0.05). Survival was 96.2% at 10 years, using as endpoint implant revision or/and progression of osteoarthritis. The cumulative hazard for any-reason reoperation was 12.0%.

CONCLUSIONS

Femoral condyle resurfacing using the HemiCAP^® device is an effective treatment option to address focal chondral and osteochondral defects. It can be successfully used either as a primary procedure or after prior biological cartilage reconstruction. Subjective clinical outcomes are expected to be good to excellent in mid- to long term, while reoperation and revision rates are low. Progression of osteoarthritis is the most common mode of failure; thus, patient selection is very important.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Focal articular surface replacement as primary treatment for focal chondral defects of the femoral condyles: A series of 157 cases

BACKGROUND

Focal chondral defects (FCDs) of the femoral condyle are common. Treatment has heretofore primarily consisted of non-surgical and biological treatments. Focal articular surface replacement (FASR) is an emerging technique utilizing small implants to essentially fill the FCD. Here we report functional outcome and re-operation rates following FASR as a primary treatment for FCDs of the femoral condyles.

METHODS

Retrospective analysis of a prospectively collected database including 327 FASR procedures was performed to identify patients who underwent FASR of the femoral condyle with a modular cementless metallic implant (HemiCAP^TM) as a primary procedure. Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), SF-36 Health Status Survey (SF-36) and Visual Analog Scale (VAS) were collected before and 6 weeks, 6 months, and 4 years after surgery. Implant revision and re-operation rate were recorded.

RESULTS

157 patients were included with a mean follow-up of 9.4 ± 1.3 years (range 7.0 to 11.4 years). The average age was 40.2 ± 5.3 years, 85% involved the medial condyle, and the average defect size was 3.6 ± 0.5 cm². Primary FASR resulted in functional improvement on the KOOS (+52%), OKS (+69%) and SF-36 (+50%) scores and a reduction in VAS scores (-70%) at 4-year follow-up. Revision rate was 0.64% and the re-operation rate was 11%.

CONCLUSION

This retrospective case-series supports primary FASR with HemiCAP^TM implants as an alternative to biological procedures to treat medium-sized FCDs (2.5-4 cm²) of the femoral condyle, although long-term follow-up is necessary to determine if the clinical outcome and low revision rate can be maintained.

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.

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.

Targeted treatment for osteoarthritis: drugs and delivery system

The management of osteoarthritis (OA) is a clinical challenge due to the particular avascular, dense, and occluded tissue structure. Despite numerous clinical reports and animal studies, the pathogenesis and progression of OA are still not fully understood. On the basis of traditional drugs, a large number of new drugs have been continuously developed. Intra-articular (IA) administration for OA hastens the development of targeted drug delivery systems (DDS). OA drugs modification and the synthesis of bioadaptive carriers contribute to a qualitative leap in the efficacy of IA treatment. Nanoparticles (NPs) are demonstrated credible improvement of drug penetration and retention in OA. Targeted nanomaterial delivery systems show the prominent biocompatibility and drug loading-release ability. This article reviews different drugs and nanomaterial delivery systems for IA treatment of OA, in an attempt to resolve the inconsonance between in vitro and in vivo release, and explore more interactions between drugs and nanocarriers, so as to open up new horizons for the treatment of OA.

Accurate Reporting of Concomitant Procedures Is Highly Variable in Studies Investigating Knee Cartilage Restoration

OBJECTIVE

Successful clinical outcomes following cartilage restoration procedures are highly dependent on addressing concomitant pathology. The purpose of this study was to document methods for evaluating concomitant procedures of the knee when performed with articular cartilage restoration techniques, and to review their reported findings in high-impact clinical orthopedic studies. We hypothesized that there are substantial inconsistencies in reporting clinical outcomes associated with concomitant procedures relative to outcomes related to isolated cartilage repair.

DESIGN

A total of 133 clinical studies on articular cartilage repair of the knee were identified from 6 high-impact orthopedic journals between 2011 and 2017. Studies were included if they were primary research articles reporting clinical outcomes data following surgical treatment of articular cartilage lesions with a minimum sample size of 5 patients. Studies were excluded if they were review articles, meta-analyses, and articles reporting only nonclinical outcomes (e.g., imaging, histology). A full-text review was then used to evaluate details regarding study methodology and reporting on the following variables: primary cartilage repair procedure, and the utilization of concomitant procedures to address additional patient comorbidities, including malalignment, meniscus pathology, and ligamentous instability. Each study was additionally reviewed to document variation in clinical outcomes reporting in patients that had these comorbidities addressed at the time of surgery.

RESULTS

All studies reported on the type of primary cartilage repair procedure, with autologous chondrocyte implantation (ACI) noted in 43% of studies, microfracture (MF) reported in 16.5%, osteochondral allograft (OCA) in 15%, and osteochondral autograft transplant (OAT) in 8.2%. Regarding concomitant pathology, anterior cruciate ligament (ACL) reconstruction (24.8%) and meniscus repair (23.3%) were the most commonly addressed patient comorbidities. A total of 56 studies (42.1%) excluded patients with malalignment, meniscus injury, and ligamentous instability. For studies that addressed concomitant pathology, 72.7% reported clinical outcomes separately from the cohort treated with only cartilage repair. A total of 16.5% of studies neither excluded nor addressed concomitant pathologies. There was a significant amount of variation in the patient reported outcome scores used among the studies, with the majority of studies reporting International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcomes Score (KOOS) in 47.2% and 43.6% of articles, respectively.

CONCLUSIONS

In this study on knee cartilage restoration, recognition and management of concomitant pathology is inadequately reported in approximately 28% of studies. Only 30% of articles reported adequate treatment of concomitant ailments while scoring their outcomes using one of a potential 18 different scoring systems. These findings highlight the need for more standardized methods to be applied in future research with regard to inclusion, exclusion, and scoring concomitant pathologies with regard to treatment of cartilage defects in the knee.

The partial femoral condyle focal resurfacing (HemiCAP-UniCAP) for treatment of full-thickness cartilage defects, systematic review and meta-analysis

Knee osteochondral defects are a common problem among people, especially young and active patients. So effective joint preserving surgeries is essential to prevent or even delay the onset of osteoarthritis for these group of patients. This study aims to critically appraise and evaluate the evidence for the results and effectiveness of femoral condyle resurfacing (HemiCAP/ UniCAP) in treatment of patients with focal femoral condyle cartilage defect. Using the search terms : HemiCAP, UniCAP, Episurf, focal, femoral, condyle, inlay and resur-facing, we reviewed the PubMed and EMBASE and the Cochrane Database of Systematic Reviews (CDSR) to find any articles published up to March 2020. The short term follow-up of the HemiCAP shows (6.74 %) revision rate. However, 29.13 % loss of follow up let us consider these results with caution especially if the revision rate progressively increased with time to 19.3 % in 5-7 years with no enough evidence for the long term results except the data from the Australian Joint Registry 2018, where the cumulative revision rate was 40.6 % (33.5, 48.4) at ten years. The UniCAP that used for defect more than 4 cm 2 has a high revision rate (53.66 %) which is considered unacceptable revision rate in com-parison to another similar prosthesis such as Uni-Knee Arthroplasty (UKA). The evidence from published studies and our meta- analysis suggests that partial resurfacing of the femoral condyle (HemiCAP) doesn’t support its usage as a tool to treat the focal cartilage defect in middle- aged patients. The UniCAP as femoral condyle resurfacing has very high revision rate at 5-7 years (53.66 %) which make us recommend against its usage.

[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.

Focal articular surface replacement of knee lesions after failed cartilage repair using focal metallic implants: A series of 132 cases with 4-year follow-up

BACKGROUND

Focal articular lesions of the knee can be treated using several different techniques with generally good results, but failures are difficult to manage. Focal articular surface replacement (FASR) using metal implants could be a promising technique that allows defect geometry matching, congruency restoration and defect propagation prevention.

METHODS

132 patients were included who underwent FASR between January 2009 and December 2013. Three different implants were used: 1. HemiCAP®; 2. UniCAP® and 3. HemiCAP® PF Classic for trochlear lesions. Primary outcome parameter was knee function assessed by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score with a 4-year follow-up, secondary outcomes included survivorship and complications. Statistical analyses were performed using GraphPad Prism.

RESULTS

For all 132 surgeries combined (102 HemiCAP®, 11 UniCAP® and 19 HemiCAP® PF Classic implants), WOMAC scores significantly improved from 6 weeks onward until the end of the study (p < 0.001 for all time points). 4-year survival rate was 97.7%, and a re-operation rate of 12.1% was found. The HemiCAP® group revealed a slower WOMAC improvement in patients aged ≥40 years, combined with a trend towards lower final WOMAC scores and a higher re-operation rate in patients with a BMI ≥ 25.

CONCLUSIONS

This report shows good to excellent clinical results of FASR as a salvage procedure after failed cartilage repair, with a low re-operation rate and a high survival of 97.7% at 4-year follow-up. Although longer follow-up is required, this could be a valuable treatment option in these challenging cases, without limiting future options for surgical interventions when deemed necessary.

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

PURPOSE

Surgical treatment options for the management of focal chondral and osteochondral lesions in the knee include biological solutions and focal metal implants. A treatment gap exists for patients with lesions not suitable for arthroplasty or biologic repair or who have failed prior cartilage repair surgery. This study reports on the early clinical and functional outcomes in patients undergoing treatment with an individualised mini-metal implant for an isolated focal chondral defect in the knee.

METHODS

Open-label, multicentre, non-randomised, non-comparative retrospective observational analysis of prospectively collected clinical data in a consecutive series of 80 patients undergoing knee reconstruction with the Episealer® implant. Knee injury and Osteoarthritis Outcome Score (KOOS) and VAS scores, were recorded preoperatively and at 3 months, 1 year, and 2 years postoperatively.

RESULTS

Seventy-five patients were evaluated at a minimum 24 months following implantation. Two patients had undergone revision (2.5%), 1 declined participation, and 2 had not completed the full data requirements, leaving 75 of the 80 with complete data for analysis. All 5 KOOS domain mean scores were significantly improved at 1 and 2 years (p < 0.001-0.002). Mean preoperative aggregated KOOS4 of 35 (95% CI 33.5-37.5) improved to 57 (95% CI 54.5-60.2) and 59 (95% CI 55.7-61.6) at 12 and 24 months respectively (p < 0.05). Mean VAS score improved from 63 (95% CI 56.0-68.1) preoperatively to 32 (95% CI 24.4-38.3) at 24 months. The improvement exceeded the minimal clinically important difference (MCID) and this improvement was maintained over time. Location of defect and history of previous cartilage repair did not significantly affect the outcome (p > 0.05).

CONCLUSION

The study suggests that at 2 years, Episealer® implants are safe with a low failure rate of 2.5% and result in clinically significant improvement. Individualised mini-metal implants with appropriate accurate guides for implantation appear to have a place in the management of focal femoral chondral and osteochondral defects in the knee.

LEVEL OF EVIDENCE

IV.

Ten-Year Average Full Follow-up and Evaluation of a Contoured Focal Resurface Prosthesis (HemiCAP) in Patients in the United Kingdom

A significant number of patients are affected by localized articular damage that is appropriate neither for traditional arthroplasty nor for biological repair. A focal resurfacing system using a matched contoured articular prosthetic (HemiCAP) has been introduced for the treatment of such cases. Independent long-term results of these implants are limited. We retrospectively evaluated the use of this resurfacing system in 14 patients (13 males, 1 female), with a mean age of 40.3 years (range: 28-49), with focal femoral condyle defects. The same consultant orthopaedic surgeon performed all procedures. Our primary outcome measure was revision rate. Secondary outcome measures included radiographic evaluation (prosthesis migration signs, radiolucency), patient-reported functional evaluation (knee injury and osteoarthritis outcome scores), and complications. A total of 10 patients were treated on the medial femoral condyle, 2 were treated on the lateral condyle, and 2 received bicondylar implants (14 in total). Average follow-up was 107 months (range: 59-135). Three patients were lost to follow-up at the time of study. One patient was excluded from the study. Of the 10 left, 2 had to be revised, leading the survival rate to be 80% at 9.4 years. In four contactable patients, average Knee injury and Osteoarthritis Outcomes score at 121 months postsurgery (9.75 years) was 92.9 (as compared with 57.7 preoperatively). There were no complications. This series demonstrates that focal resurfacing is a safe, suitable, and useful temporizing step in knee arthroplasty surgery. The use of the focal resurfacing implant in this way allows the delay in transition to knee arthroplasty. This series shows an excellent functional outcome for remaining implants at average 10 years, with low complication rates.

Focal inlay resurfacing for full-thickness chondral defects of the femoral medial condyle may delay the progression to varus deformity

INTRODUCTION

Full-thickness chondral defects at the knee joint predispose to the beginning of a degenerative process which final consequence is the compartment collapse and finally the deviation to varus, because the cartilage of the medial femoral condyle is the most frequently affected area. Likewise, people with these chondral defects are more likely to develop tricompartmental osteoarthritis, reason why early surgical management should be the treatment of choice. The aim of this study was to compare the pre- and post-operative lower limb alignment (mechanical axis), in cases of full-thickness chondral defects of the femoral medial condyle that have been managed by means of a prosthetic focal inlay resurfacing, at a minimum follow-up of five years.

METHODS

A retrospective study of patients treated for chondral defects in the medial femoral condyle was performed. The inclusion criteria were patients who had undergone a focal inlay resurfacing and minimum follow-up of 5 years. Patients that required a concomitant valguizing tibial osteotomy were finally excluded. The follow-up analysis was performed by means of radiological examinations performed prior to surgery and at the last follow-up visit. The mean limb mechanical axis of the operated knees was calculated both pre- and post-operatively, and comparisons between these two settings were performed.

RESULTS

Ten patients were included: eight men and two women. The mean age at the time of surgery was 55 (40-65) years. The mean follow-up was 9 years (range 5-15). The mean limb mechanical axis was 1.33 ± 4.16 in the pre-operative setting and 2.40 ± 5.50 in the post-operative setting (p = 0.441).

CONCLUSION

In the setting of small to moderate size, unique femoral medial condyle full-thickness chondral lesions, filling the defect with an inlay prosthetic resurfacing may protect against the progression to varus deformity.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

In vitro and in vivo study on the osseointegration of BCP-coated versus uncoated nondegradable thermoplastic polyurethane focal knee resurfacing implants

Focal knee resurfacing implants (FKRIs) are intended to treat cartilage defects in middle-aged patients. Most FKRIs are metal-based, which hampers follow-up of the joint using magnetic resonance imaging and potentially leads to damage of the opposing cartilage. The purpose of this study was to develop a nondegradable thermoplastic polyurethane (TPU) FKRI and investigate its osseointegration. Different surface roughness modifications and biphasic calcium phosphate (BCP) coating densities were first tested in vitro on TPU discs. The in vivo osseointegration of BCP-coated TPU implants was subsequently compared to uncoated TPU implants and the titanium bottom layer of metal control implants in a caprine model. Implants were implanted bilaterally in stifle joints and animals were followed for 12 weeks, after which the bone-to-implant contact area (BIC) was assessed. Additionally, 18F-sodium-fluoride (18F-NaF) positron emission tomography PET/CT-scans were obtained at 3 and 12 weeks to visualize the bone metabolism over time. The BIC was significantly higher for the BCP-coated TPU implants compared to the uncoated TPU implants (p = .03), and did not significantly differ from titanium (p = .68). Similar 18F-NaF tracer uptake patterns were observed between 3 and 12 weeks for the BCP-coated TPU and titanium implants, but not for the uncoated implants. TPU FKRIs with surface modifications could provide the answer to the drawbacks of metal FKRIs.

[Effectiveness of arthroscopic microfracture combined with osteochondral autologous transplantation for large area cartilage injury of femoral condyle of knee]

Objective

To explore the effectiveness of arthroscopic microfracture combined with osteochondral autologous transplantation (OAT) in treatment of large area (4-6 cm ²) cartilage injury of the femoral condyle of knee.

Methods

Between March 2016 and June 2017, 22 patients of large area cartilage injury of the femoral condyle of knee were treated with arthroscopic microfracture combined with OAT. There were 16 males and 6 females with an average age of 22-60 years (mean, 38.6 years). The cause of injury was traffic accident in 8 cases and sports injuries in 14 cases. The disease duration was 1-6 months (mean, 3.4 months). There were 15 cases of medial femoral condyle injuries and 7 cases of lateral condyle injuries. The area of cartilage defect was 4-6 cm ² (mean, 4.98 cm ²). According to the International Cartilage Repair Society (ICRS) classification, 9 cases were rated as grade Ⅲ and 13 cases as grade Ⅳ. Eighteen cases were combined with meniscus injuries. Preoperative visual analogue scale (VAS) score was 6.36±1.25 and Lysholm score was 36.00±7.77.

Results

All incisions healed by first intention. All patients were followed up 2-3 years with an average of 2.3 years. At 2 years after operation, the VAS score was 1.27±0.94 and the Lysholm score was 77.82±6.21, which were significantly improved when compared with those before operation ( t=16.595, P=0.000; t=21.895, P=0.000). At 2 years after operation, MRI showed that the cartilage defect was repaired well.

Conclusion

Arthroscopic microfracture combined with OAT can be used to treat large area cartilage injury of the femoral condyle of knee, and the good early effectiveness can be obtained.

Focal metallic inlay resurfacing prosthesis in articular cartilage defects: short-term results of 118 patients and 2 different implants

BACKGROUND

The goal of this study was to share our experience with two different inlay metallic implants in the treatment of knee cartilage defects and to analyze their effects on functional scores.

METHODS

This retrospective study included 118 patients operated on for focal full-thickness knee cartilage lesions, who were treated with a focal metallic inlay resurfacing prosthesis. A cobalt-chromium (Co-Cr) resurfacing implant was applied to 73 patients with a knee chondral lesion, and a biosynthetic implant was applied to 45. All patients were evaluated preoperatively and postoperatively using the KOOS, VAS, and Tegner activity scores.

RESULTS

The group with the Co-Cr-resurfacing implant showed a significantly greater improvement (p < 0.001) in the Tegner and VAS scores at the 2-year follow-up examination. The KOOS scores were similar in both groups. Median patient age was similar in both groups. All patients had a follow-up of at least 2 years. The preoperative and postoperative scores were compared and significant improvements (p < 0.001) were observed. The biosynthetic implant had a higher revision rate. In the univariate analysis, age and type of implant were significantly associated with revision surgery. In the multivariate Cox-regression analysis model, the type of implant was significantly associated with revision surgery.

CONCLUSION

All the patients operated with the above-mentioned implants showed significant improvements in pain and activity scores. Despite the overall good clinical results, 17% of patients with a biosynthetic implant and > 6% of patients with Co-Cr-resurfacing implant required revision surgery. Age and implant type were the main risk factors associated with revision.

A large knee osteochondral lesion treated using a combination of osteochondral autograft transfer and second-generation autologous chondrocyte implantation: A case report

Background

Full-thickness knee cartilage defects greater than 4 cm² are best treated with autologous chondrocyte implantation (ACI). Since the articular cartilage surrounding the site of implantation does not always have the normal thickness desirable for successful engraftment, there may be benefit in combining ACI with osteochondral autograft transfer, which provides immediate restoration of condylar contour and mechanical function.

Case presentation

A 19 year-old male who sustained a traumatic anterolateral femoral condyle osteochondral fracture underwent arthroscopic knee surgery three months after injury to harvest healthy cartilage to be sent to the Japan Tissue Engineering Co., Ltd. (J-TEC) for cartilage culture. The patient was re-admitted after four weeks to undergo a procedure using the Osteochondral Autograft Transfer System (OATS®) and the J-TEC autologous cultured cartilage (JACC®) system. Three 4.75-mm osteochondral cylindrical cores were harvested from non-weight-bearing areas of the knee and were transplanted to the lateral periphery of the lateral femoral condyle defect. The cultured cartilage was implanted to the remaining defect with a periosteal cover harvested from the anterolateral ridge of the lateral femoral condyle. Continuous passive range of motion exercises and gait retraining were immediately initiated, with strict no weight-bearing precaution on the operated limb. Partial weight-bearing was allowed four weeks after surgery, which was progressed to full weight-bearing after another two weeks.

Conclusion

ACI must be viewed as a complementary procedure to osteochondral transplantation and this hybrid technique appears to be a promising surgical approach and treatment option for large cartilage lesions, especially in the younger population.

Focal metallic inlay resurfacing prosthesis for the treatment of localized cartilage defects of the femoral condyles: a systematic review of clinical studies

PURPOSE

To systematically review the results of focal metallic inlay resurfacing prosthesis for the treatment of isolated cartilage defects of the femoral condyles.

METHODS

A systematic electronic search of the PubMed database and the Cochrane Library was performed in April 2017 to identify studies that reported clinical or radiographic outcome of focal metallic inlay resurfacing prosthesis for the treatment of isolated cartilage defects of the femoral condyles. Included studies were abstracted regarding study characteristics, patient demographics, prosthetic device and location, indications and contraindications, and outcome measures. Outcome of interest included functional outcome scores, radiographic measures, complications, re-operations, and conversion to arthroplasty. The methodologic quality of the included studies was assessed with the Coleman Methodology Score.

RESULTS

Six studies with a total of 186 patients met the inclusion criteria. Five studies were level IV evidence, and one was level III. The methodologic quality of the included studies was good, with a mean Coleman Methodology Score of 78. Two different implants were used: the HemiCAP^® (five studies; 66% of study group) and UniCAP^® (one study; 34%) implant. The mean age was 46-54 years, and the mean follow-up was 24 months to 7 years. Pre- and post-operative outcome scores were compared in all six studies, and five studies reported significant improvements at the final follow-up for all scores (objective und functional KSS, KOOS, WOMAC, Tegner, HSS Knee and Function score, SF-36 and SF-12 physical component score) except for the SF-36 and SF-12 mental component score. Progression of osteoarthritis was analysed using the Kellgren-Lawrence grading in three studies (30% of study group), with two studies reporting significant progression. The OARSI grading system was analysed in one study with no significant progression. The overall conversion rate to arthroplasty was 22% with considerable differences between the two implants: 9% for HemiCAP^® and 47% for UniCAP^®.

CONCLUSIONS

Focal metallic inlay resurfacing prosthesis seems to be a viable option for a carefully selected group of patients. Significant improvement in knee function and pain was observed in most patients. Uncertainty remains with regard to progression of osteoarthritis because of conflicting results and inconsistent reporting. One out of five patients has to be converted to arthroplasty after an average of 4 years. However, compared to the UniCAP^® implant, considerable lower conversion rates were reported for the smaller HemiCAP^® implant.

LEVEL OF EVIDENCE

Systematic review of level III and IV studies, Level IV.

The clinical outcome of the different HemiCAP and UniCAP knee implants: A systematic and comprehensive review

The focal metallic cartilage resurfacing is a surgical method that offers an appropriate step between the biological techniques and arthroplasty in middle-aged patients with full-thickness cartilage defects. The advantages of this technique are that it addresses the defect, respects healthy tissues and provides stability and contoured surface similar to a full arthroplasty. A systematic review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Two reviewers (MM and DC) independently conducted the search using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews (CDSR). These databases were searched for the terms hemicap knee implant and unicap knee implant and knee focal metallic implant. From the initial 21 studies that were evaluated, 10 were eligible for analysis. Considering both the HemiCAP focal implant and the HemiCap^® Wave patellofemoral prosthesis, we found a lack of mid- to long-term clinical outcomes in well-designed prospective clinical studies. No Level I or II studies were found, while the limited number of patients who were included undermines the overall clinical results of these studies. The progression of osteoarthritis, the persisting pain and the subsequent high revision or failure rates in the limited available studies with long-term follow-up, seem to be the major drawbacks of these partial resurfacing techniques. Utilization of partial resurfacing for femoral or patellofemoral compartments results in good short-term outcome for middle-aged patients as a step between biological technique and total knee arthroplasty. The surgeon should be cognizant and also notify the patient of the high failure rates that are reported in the literature in mid- to longterm follow-up and ultimately, the decision to perform partial resurfacing should be taken by both the patient and the orthopedic surgeon.

Focal articular prosthetic resurfacing for the treatment of full-thickness articular cartilage defects in the knee: 12-year follow-up of two cases and review of the literature

INTRODUCTION

The rationale of focal articular prosthetic resurfacing used as a primary arthroplasty procedure in the treatment of articular cartilage defects is still under debate. Conflicting reports raise concern about high rates of re-operations and continued development of osteoarthritis, while others have reported good outcomes. The goal of this paper is to present the long-term results of two patients with a 12-year follow-up and to report the results of a literature review.

MATERIALS AND METHODS

Two patients (male, 70 years; female 63 years) with a follow-up of 12 years were reviewed. Patients were evaluated with standard radiographs to assess the progression of osteoarthritis (OA), a clinical examination including the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Tegner activity scale. The literature review was performed using the search terms HemiCAP, focal, femoral, condyle, inlay, and resurfacing to identify articles published in the English language up until September 25, 2016.

RESULTS

The clinical and radiographic follow-ups of the patients were 11.9 and 11.8 years, respectively. Both patients were satisfied with their outcome and would have the operation again. Comparing the first postoperative to 12-year follow-up X-rays, the radiographic results demonstrated no signs of periprosthetic loosening, preservation of joint space, and no change in the osteoarthritic stage. KOOS Scores were 86 and 83 for pain, 89 and 93 for symptoms, 88 and 100 for activities of daily living (ADL), 75 and 65 for sports and recreation, and 75 and 81 for quality of life (QOL). The Tegner activity level was 5 and 4. The literature review comprised 6 studies with 169 focal articular prosthetic resurfacing procedures in 169 patients (84 male, 85 female) with a mean age at implantation ranging from 44.7 to 53.7 years and a follow-up range of 20 months to 7 years. Five studies were classified as level 4 and one as level 3. Clinical and radiographic results showed mainly good to excellent outcomes but were different among the studies depending on the indication. Re-operation rates ranged from 0 to 23% depending on the length of follow-up.

CONCLUSIONS

The results suggest that focal articular prosthetic resurfacing is an effective and safe treatment option in selected cases.