Osteochondral Plugs Research Articles

Characterization of biological and mechanical properties of 3D-bioprinted osteochondral plugs

Three-dimensional (3D) bioprinting offers significant potential for the repair of articular cartilage by engineering functional osteochondral tissue. However, progress has been hindered by a lack of printable bioinks that promote the development of bone and chondral tissue while also maintaining sufficient cytocompatibility and mechanical strength. Herein, we designed a biphasic osteochondral plug with distinct chondral and bone regions and developed suitable bioinks for each tissue using photorheology and compression testing. The chondral region consisted of human bone marrow-derived mesenchymal stem cells (hbMSCs) encapsulated in a chondral bioink composed of methacrylated hyaluronic acid and high molecular weight hyaluronic acid. The bone region was 3D bioprinted from an hbMSC-laden methacrylated gelatin (GelMA) bioink and a biodegradable thermoplastic and ceramic lattice that provided mechanical strength. The viability and functionality of hbMSC encapsulated in the bioinks were confirmed through live/dead assays, histology, biochemical assays, and fluorescence microscopy. Over 56 days of culture in a chondrogenic medium, hbMSCs encapsulated in chondral bioink deposited cartilage-like extracellular matrix components, such as type II collagen and glycosaminoglycans. Similarly, cells encapsulated in the bone bioink and cultured in osteogenic medium deposited hydroxyapatite, a key component of bone. These findings provide promising initial results for using 3D-bioprinted plugs to repair osteochondral defects in articular cartilage.  

Fresh Osteochondral Allograft Transplantation of the Capitellum for the Treatment of Osteochondritis Dissecans

Background: Osteochondritis dissecans (OCD) of the humeral capitellum is a rare and challenging condition to treat. Several surgical options exist, but in the last few years, the pendulum has swung from debridement and microfracture to restoration of the articular surface. Osteochondral autografts from the rib and knee have been described, but donor-site morbidity is a concern. Purpose: To expand the results of fresh osteochondral allograft transplantation (FOCAT) in a previously published report with inclusion of additional patients and a longer follow-up period. Study Design: Case series; Level of evidence, 4. Methods: After institutional review board approval, the charts of patients who underwent FOCAT for OCD of the capitellum between 2006 and 2022 by a single surgeon were reviewed. The majority of cases (94%) had unstable lesions (Minami grades 2 and 3). A trial of nonoperative treatment had failed in all. All patients underwent diagnostic arthroscopy, followed by a mini-open, ligament-sparing approach with grafting using commercially available guides and instruments. Results: A total of 35 patients were identified, of whom 25 were male. The mean age was 16 ± 3.9 years (range, 11-32 years). There were 24 baseball players (19 pitchers and 5 position players), 5 gymnasts, 3 cheerleaders/tumblers, 1 tennis player, 1 student (who did not participate in athletics), and 1 patient with avascular necrosis from chemotherapy. Eighteen patients had a mean flexion contracture of 14.1°± 11.9°. A single osteochondral allograft plug was used in 23 patients (mean diameter, 11.3 ± 2.8 mm), and 12 patients required 2 plugs (Mastercard technique). The mean follow-up was 92.6 ± 54.5 months (range, 24-204 months). There was significant improvement in Oxford (from 25.5 ± 4.9 to 46.7 ± 3.5; P < .00001) and visual analog scale for pain (from 7.5 ± 2 to 0.3 ± 1.0; P < .0001) scores. The mean Single Assessment Numeric Evaluation score at the time of follow-up was 90.6 ± 10.8 (range, 60-100). In overhead athletes, there was significant improvement in the Kerlan-Jobe Orthopaedic Clinic score (from 40.8 ± 11.8 to 90.6 ± 10.8; P < .00001). A postoperative magnetic resonance imaging scan was obtained in 16 (46%) patients at a mean of 32.6 months. In all cases, the graft was incorporated. All overhead athletes were able to return to their sport and perform at the same level or higher for >2 years. Two elbows required a subsequent arthroscopy for loose-body removal; otherwise, there were no other complications. Conclusion: FOCAT is an excellent option for treating OCD lesions of the humeral capitellum. Excellent outcomes and high return-to-sport rates were observed, with midterm follow-up showing no graft failures. FOCAT eliminates donor-site morbidity.

Outcomes following Arthroscopic Treatment of Off-Track Hill-Sachs Lesions Using Fresh Osteochondral Allograft Plugs: A Case Series

BackgroundOsteochondral allograft (OCA) transplantation is a well-described technique for the treatment of large, engaging Hill-Sachs lesions (HSLs). Traditionally, OCAs are size-matched to the defect, which can be expensive and time-consuming, and the majority of described techniques require an open approach. Recently, an all-arthroscopic approach to Hill-Sachs OCA transplantation using premade plugs was described, eliminating the need for size-matching and graft harvest. Hypothesis/PurposeThe purpose of this study was to evaluate postoperative outcomes of patients who have undergone arthroscopic treatment of HSLs using premade OCA plugs. We hypothesized that these patients would have improved pain and function without recurrent instability. MethodsA retrospective chart review was performed using operative reports for a single surgeon with search terms “Hill-Sachs” and “allograft.” Patients were excluded if an open approach was used or if graft harvest was performed. Postoperative imaging was reviewed to assess for graft incorporation and reconstitution of the HSL. Recurrent instability and reoperation were recorded. Patients completed surveys including the American Shoulder and Elbow Surgeons (ASES) score and the Western Ontario Shoulder Instability Index (WOSI). ResultsFive patients were identified through chart review and met inclusion criteria. All patients underwent concurrent labral repair and two patients underwent a concurrent open Latarjet procedure. Postoperative radiographs showed reconstitution of the HSLs in all patients. There were no complications in the postoperative period with no recurrent instability or reoperations in any patient. The average ASES score was 87% (higher score indicating better outcome) with standard deviation 9.7, and the average WOSI score was 27% (lower score indicating better outcome) with standard deviation 8.3. ConclusionFavorable outcomes can be expected after arthroscopic treatment of Hill-Sachs lesions using premade OCA plugs. Further research is needed to assess larger patient cohorts and compare outcomes to size-matched approaches.

Measurement of T1ρ dispersion with compressed sensing and magnetization prepared radial balanced steady-state free precessionin spontaneous human osteoarthritis.

To assess the potential for accelerating continuous-wave (CW) T1ρ dispersion measurement with compressed sensing approach via studying the effect that the data reduction has on the ability to detect differences between intact and degenerated articular cartilage with different spin-lock amplitudes and to assess quantitative bias due to acceleration. Osteochondral plugs (n = 27, 4 mm diameter) from femur (n = 14) and tibia (n = 13) regions from human cadaver knee joints were obtained from commercial biobank (Science Care, USA) under Ethical permission 134/2015. MRI of specimens was performed at 9.4T with magnetization prepared radial balanced SSFP (bSSFP) readout sequence, and the CWT1ρ relaxation time maps were computed from the measured data. The relaxation time maps were evaluated in the cartilage zones for different acceleration factors. For reference, Osteoarthritis Research Society International (OARSI) grading and biomechanical measurements were performed and correlated with the MRI findings. Four-fold acceleration of CWT1ρ dispersion measurement by compressed sensing approach was feasible without meaningful loss in the sensitivity to osteoarthritic (OA) changes within the articular cartilage. Differences were significant between intact and OA groups in the superficial and transitional zones, and CWT1ρ correlated moderately with the reference measurements (0.3 < r < 0.7). CWT1ρ was able to differentiate between intact and OA cartilage even with four-fold acceleration. This indicates that acceleration of CWT1ρ dispersion measurement by compressed sensing approach is feasible with negligible loss in the sensitivity to osteoarthritic changes in articular cartilage.

A Unique Approach to Irreparable Radial Head Fracture Using an Osteochondral Plug: A Case Report.

An 18-year-old male patient sustained a traumatic injury that resulted in the loss of approximately 50% of the radial head. Subsequently, reconstruction was performed by transplanting an osteochondral plug harvested from the lateral femoral condyle. At the 1-year postoperative follow-up, the patient was pain-free and had a good range of motion. Using a novel technique, an irreparable radial head fracture was reconstructed using an osteochondral plug from the lateral femoral condyle. Reconstruction with osteochondral plugs may be a treatment option for partial loss of the radial head.

Poster 281: What Donor Region has the Lowest Risk of Fracture During Insertion of an Osteochondral Autograft Transfer Plug: A Human Cadaver Analysis

Poster 281: What Donor Region has the Lowest Risk of Fracture During Insertion of an Osteochondral Autograft Transfer Plug: A Human Cadaver Analysis

AUTOLOGOUS OSTEOCHONDRAL TRANSPLANTATION FOR LARGE OSTEOCHONDRAL LESIONS OF THE TALUS IS A VIABLE OPTION IN AN ATHLETIC POPULATION

Autologous osteochondral transplantation (AOT) is an effective treatment for large Osteochondral Lesions of the Talus (OLT), however little is reported on an athletic population, who are likely to place higher demands on the reconstruction. The aim is to report the outcomes of large OLT (&gt;150mm2) within an athletic population. The study population was limited to professional or amateur athletes (Tegner score &gt;6) with an OLT of size 150mm2 or greater. The surgical intervention was AOT with a donor site from the lateral femoral condyle. Clinical outcomes at a minimum of 24 months included Return to Sport, VAS and FAOS Scores. In addition, graft incorporation was evaluated by MRI using MOCART scores at 12 months post-surgery. 38 athletes including 11 professional athletes were assessed. Mean follow-up was 46 months. Mean lesion size was 249mm2. 33 patients returned to sport at their previous level and one did not return to sport (mean return to play 8.2 months). Visual analogue scores improved from 4.53 pre-operatively to 0.63 post-operatively (p=0.002). FAOS Scores improved significantly in all domains (p&lt; 0.001). Two patients developed knee donor site pain, and both had three osteochondral plugs harvested. Univariant analysis demonstrated no association between pre-operative patient or lesion characteristics and ability to return to sport. However, there was a strong correlation between MOCART scores and ability to return to sport (AUC=0.89). Our study suggests that AOT is a viable option in the management of large osteochondral talar defects in an athletic population, with favourable return to sport levels, patient satisfaction, and FAOS/VAS scores. The ability to return to sport is predicated upon good graft incorporation and further research is required to optimise this technique. Our data also suggests that patients should be aware of the increased risk of developing knee donor site pain when three osteochondral plugs are harvested.

Effects of dexamethasone and IGF-1 on post-traumatic osteoarthritis-like catabolic changes in a human cartilage-bone-synovium microphysiological system in space and ground control tissues on earth

Post-traumatic Osteoarthritis (PTOA) results from traumatic joint injuries (such as an ACL rupture). Mechanical impact and an immediate synovial inflammatory response can result in joint tissue degradation and longer-term progression to PTOA. Astronauts are susceptible to increased exercise-related joint injuries leading to altered musculoskeletal physiology, further escalated due to microgravity and increased exposure to ionizing radiation. We applied a human Cartilage-Bone-Synovium (CBS) coculture model to test the potential of low-dose dexamethasone (Dex) and IGF-1 in ameliorating PTOA-like degeneration on Earth and the International Space Station-National Laboratory (ISS-NL, ISS for short). CBS cocultures were established using osteochondral plugs (CB) subjected to compressive impact injury (INJ) followed by coculture with synovium (S) explants. Study groups consisted of control (CB); disease [CBS + INJ]; treatment [CBS + INJ + Dex + IGF-1]; and drug-safety [CB + Dex + IGF-1]. Outcome measures included cell viability, altered matrix glycosaminoglycans (GAG) and collagens, multiplex-ELISA quantification of released cytokines, histopathology, and metabolomic and proteomic analyses of spent media. A 21-day study on ISS-NL explored PTOA-like pathogenesis and treatment in microgravity. Tissue cards for study groups were cultured in custom-built culture chambers within multi-use variable-g platforms (MVPs). A marked upregulation in the release of inflammatory cytokines and tissue-GAG loss was observed in CBS + INJ groups in space and ground controls utilizing tissues from the same donors, similar to that reported in a previous multi-donor study on Earth; these changes were partly ameliorated by Dex + IGF-1, but with donor variability. Metabolomic and proteomic analyses revealed an array of distinct differences between metabolites/proteins released to the medium in Space versus on Earth.

Surgical Management of Osteochondritis Dissecans of the Glenoid via Autologous Bone Marrow Aspirate Concentrate and Extracellular Matrix Graft in an Eighteen-Year-Old College Pitcher

Background: Osteochondritis dissecans (OCD) affects the shoulder in only 0.6% of patients aged 2 to 19 years with disease most commonly in the humeral head. When the glenoid is affected, it is often in male overhead throwing athletes and treated with fixation via autologous osteochondral plugs following bone marrow aspirate. Indications: The primary indication for surgical management of OCD is failure of conservative management, often with imaging showing disruption of the glenoid subchondral plate. This patient is an 18-year-old male pitcher with over 2 years of chronic, deep-seated shoulder pain unresponsive to conservative management. Technique Description: We present a primary arthroscopic technique of autologous bone marrow aspirate concentrate graft for management of OCD in an 18-year-old college baseball pitcher. The patient was placed in the left lateral decubitus position with an axillary roll and standard portals were established. A loose fragmented flap with no underlying osseous material was debrided and a 3-cm central area of bony loss was identified. Bone marrow aspirate of 80 mL was taken from the anterior superior iliac crest. The aspirate was mixed with Biocartilage (Arthrex) to fill the defect flush with the surrounding tissue and sealed with fibrin glue. Ports were closed and an abduction sling was applied. Results: A recent review article demonstrated that athletes who underwent surgical management of OCD lesions returned to sports an average of 1.2 months sooner than those managed non-operatively, though this difference was not significant. This patient had a full return to play at 9 months. At 1-year follow-up, he made a full recovery and is currently playing professionally without shoulder pain. Discussion/Conclusion: Autologous bone marrow aspirate defect filling is a viable treatment of OCD, even in high-level overhead throwing athletes. It allows for arthroscopic treatment with long-term success in the treatment of pain and function. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Comparison of two contrast-enhancing staining agents for use in X-ray imaging and digital volume correlation measurements across the cartilage-bone interface

ObjectiveThe pathogenesis of osteoarthritis (OA) is associated with subchondral bone changes, which is linked to abnormal strain distribution in the overlying articular cartilage. This highlights the importance of understanding mechanical interaction at the cartilage-bone interface. The aim of this study is to compare solutions of two contrast-enhancing staining agents (CESA) for combining high-resolution Contrast-Enhanced X-ray microfocus Computed Tomography (CECT) with Digital Volume Correlation (DVC) for full-field strain measurements at the cartilage-bone interface. DesignBovine osteochondral plugs were stained with phosphotungstic acid (PTA) in 70% ethanol or 1:2 hafnium-substituted Wells-Dawson polyoxometalate (Hf-WD POM) in PBS. Mechanical properties were assessed using micromechanical probing and nanoindentation. Strain uncertainties (from CECT data) were evaluated following two consecutive unloaded scans. Residual strains were computed following unconfined compression (ex situ) testing. ResultsPTA and Hf-WD POM enabled the visualisation of structural features in cartilage, allowing DVC computation on the CECT data. Residual strains up to ∼10,000 μɛ were detected up to the tidemark. Nanoindentation showed that PTA-staining caused an average ∼6-fold increase in articular cartilage stiffness, a ∼19-fold increase in reduced modulus and ∼7-fold increase in hardness, whereas Hf-WD POM-stained specimens had mechanical properties similar to pre-stain tissue. Micromechanical probing showed a 77% increase in cartilage surface stiffness after PTA-staining, in comparison to a 16% increase in stiffness after staining with Hf-WD POM. ConclusionHf-WD POM is a more suitable CESA solution compared to PTA for CECT imaging combined with DVC as it allowed visualisation of structural features in the cartilage tissue whilst more closely maintaining tissue mechanical properties.

MONITORING IN VITRO AND EX VIVO INFLAMMATION USING SINGLE-WALLED CARBON NANOTUBES (SWCNTS) SENSOR TECHNOLOGY

Osteoarthritis (OA) is a degenerative joint disease affecting millions worldwide. Early detection of OA and monitoring its progression is essential for effective treatment and for preventing irreversible damage. Although sensors have emerged as a promising tool for monitoring analytes in patients, their application for monitoring the state of pathology is currently restricted to specific fields (such as diabetes). In this study, we present the development of an optical sensor system for real-time monitoring of inflammation based on the measurement of nitric oxide (NO), a molecule highly produced in tissues during inflammation.Single-walled carbon nanotubes (SWCNT) were functionalized with a single-stranded DNA (ssDNA) wrapping designed using an artificial intelligence approach and tested using S-nitroso-N-acetyl penicillamine (SNAP) as a standard released-NO marker. An optical SWIR reader with LED excitation at 650 nm, 730 nm and detecting emission above 1000 nm was developed to read the fluorescence signal from the SWCNTs. Finally, the SWCNT was embedded in GelMa to prove the feasibility of monitoring the release of NO in bovine chondrocyte and osteochondral inflamed cultures (1–10 ng/ml IL1β) monitored over 48 hours. The stability of the inflammation model and NO release was indirectly validated using the Griess and DAF-FM methods. A microfabricated sensor tag was developed to explore the possibility of using ssDNA-SWCNT in an ex vivo anatomic set-up for surgical feasibility, the limit of detection, and the stability under dynamic flexion.The SWCNT sensor was sensitive to NO in both in silico and in vitro conditions during the inflammatory response from chondrocyte and osteochondral plug cultures. The fluorescence signal decreased in the inflamed group compared to control, indicating increased NO concentration. The micro-tag was suitable and stable in joints showing a readable signal at a depth of up to 6 mm under the skin.The ssDNA-SWCNT technology showed the possibility of monitoring inflammation continuously in an in vitro set-up and good stability inside the joint. However, further studies in vivo are needed to prove the possibility of monitoring disease progression and treatment efficacy in vivo.Acknowledgments: The project was co-financed by Innosuisse (grant nr. 56034.1 IP-LS)

Use of a novel magnetically actuated compression system to study the temporal dynamics of axial and lateral strain in human osteochondral plugs

The high water content of articular cartilage allows this biphasic tissue to withstand large compressive loads through fluid pressurization. The system presented here, termed the “MagnaSquish”, provides new capabilities for quantifying the effect of rehydration on cartilage behavior during cyclic loading. An imbalanced rate of fluid exudation during load and fluid re-entry during recovery can lead to the accumulation of strain during successive loading cycles - a phenomenon known as ratcheting. Typical experimental systems for cartilage biomechanics use continuous contact between the platen and sample, which may affect tissue rehydration by compressing the top layer of cartilage and slowing fluid re-entry. To address this limitation, we developed a magnetically actuated device that provides full lift-off of the platen in between loading cycles. We investigated strain accumulation in cadaveric human osteochondral plugs during 750 loading cycles, with two dimensional profiles of the cartilage captured at 30 frames per second throughout loading and 10 min of additional free swelling recovery. Axial and lateral strain measurements were extracted from the tissue profiles using a UNet-based deep learning algorithm to circumvent manual tracing. We observed increased axial strain accumulation with shorter inter-cycle recovery, with static loading serving as the extreme case of zero recovery. The loading waveform during the 750 cycles dictated the pace of the recovery during the extended free swelling period, as shorter inter-cycle recovery led to more persistent axial strain accumulation for up to five minutes. This work showcases the importance of fluid re-entry in resisting strain accumulation during cyclical compression.

In Situ Deposition of Drug and Gene Nanoparticles on a Patterned Supramolecular Hydrogel to Construct a Directionally Osteochondral Plug

HighlightsA multifactorial and oriented scaffolds was constructed to stimulate osteochondral regeneration.This is the first demonstration that both drug and gene nanoparticles were spatially deposited on a patterned film through metal-ligand interactions.For the first time, film-rolling approach was employed to construct osteochondral plug to mimick the Haversian canal structure of natural bone.

All-Arthroscopic Treatment of Off-Track Hill–Sachs Lesions Using Fresh Osteochondral Allograft Plugs: “Rocks in a Stream”

Osteochondral allograft transplantation is a well-described technique for the treatment of large, engaging Hill–Sachs lesions. Traditionally, osteochondral allografts are size-matched to the defect, which can be expensive and time-consuming, and the majority of described techniques require an open approach. This Technical Note describes an all-arthroscopic approach to Hill–Sachs osteochondral allograft transplantation using premade osteochondral allograft plugs, eliminating the need for size-matching and graft harvest. This approach works not by anatomically filling the defect, but rather by bridging the defect to prevent it from engaging the glenoid.

Reinforcing Tissue‐Engineered Cartilage: Nanofibrillated Cellulose Enhances Mechanical Properties of Alginate Dialdehyde–Gelatin Hydrogel

Cartilage tissue engineering offers a promising option for treating osteochondral defects. Alginate dialdehyde–gelatin (ADA–GEL) hydrogel has been explored as promising material for soft tissue scaffolds; however, its low stiffness has posed a constraint to load bearing applications. Herein, this limitation is addressed by introducing nanofibrillated cellulose (NFC) into the ADA–GEL matrix. The effect of NFC on the physicochemical properties of hydrogels is evaluated. Fourier transform infrared spectra demonstrate no chemical interaction between NFC and ADA–GEL, while scanning electron microscopy pictures reveal NFC fibers embedded in the hydrogel matrix, thus confirming the fiber‐reinforced composite hypothesis. NFC‐reinforced ADA–GEL (AG‐N) composite hydrogels exhibit increased stiffness, with a maximum compressive effective modulus of 19.6 ± 3.0 kPa at 25% w/w NFC content. ATDC5 cell viability and proliferation as well as chondrogenic differentiation are assessed using immunohistochemical staining for sulfated glycosaminoglycans and collagen type II. A possible application of AG‐N hydrogels as an osteochondral plug is also proposed, with polyetheretherketone as the subchondral bone anchor part. The mechanical properties of the resulting osteochondral device highlight its potential as a promising biomaterial for treatment of osteochondral defects. These findings provide valuable insights into the development of AG‐N hydrogels for load‐bearing tissue engineering applications.

Paper 10: Characterization of Bone in Osteochondral Allografts Utilizing Inflammatory-Mediated Cellular Death Pathways

Objectives: Osteochondral allografts are used to treat chondral and osteochondral defects. While prior studies have correlated cell death within the chondral component of osteochondral allografts directly with clinical outcomes, cell death within the subchondral and trabecular bone has not been well characterized. While prior studies have demonstrated a role for apoptosis in chondral cell death in osteochondral allografts, none have examined the role of pyroptosis and necroptosis in osteochondral allografts. These pathways are of particular relevance because persistent inflammation associated with osteochondral allografts on imaging is correlated with poor patient-reported outcomes. We report here a study examining cell death and mechanism in osteochondral allografts. Methods: Fresh human talus allografts were cultured for 14, 28, or 42 days at 4oC in standard clinical media. Osteochondral plugs were taken at the specified time points and fixed in 10% formalin. Cell death was measured in the cartilage, subchondral bone, and trabecular bone with TUNEL staining. The mechanism of cell death was further examined with staining for apoptosis (activated caspase 3), necroptosis (MLKL), and pyroptosis (cleaved gasdermin D). Percentage of cells staining positive was calculated in each zone (cartilage, subchondral bone, trabecular bone). Each time point included 4-5 replicates. Appropriate statistical comparisons were made between groups. Results: Cell death was significantly greater in the trabecular bone and subchondral bone than the cartilage. There was an increase in cell death over time in cartilage as well as subchondral bone. Apoptosis was the most prevalent mechanism of cell death, but necrosis and pyroptosis were present in all areas of bone and cartilage. Conclusions: This study suggests that a component of osteochondral allograft clinical outcomes may be related to viability of the bony component of the allograft. There is significantly greater cell death in the bone versus the cartilage and a significantly greater percentage of the cell death is through pyroptosis, an inflammatory-mediated pathway. Culture media and surgical strategies that limit the effect of inflammatory cell death in the bone component of osteochondral allograft may help to improve postoperative incorporation and control persistent inflammation that can complicate surgical outcomes.

Osteochondral Allograft and Concurrent Meniscal Allograft Transplantation

Background: Symptomatic, full-thickness chondral defects often are associated with meniscal deficiencies. These are difficult problems to manage in the young, high-demand patient population. A number of differing techniques have been published with no consensus. While more recent techniques have favored minimally invasive approaches, an open approach with tubercle osteotomy to maximize visualization of all knee compartments can still provide favorable outcomes when using a careful technique and postoperative protocol. Indications: Young, high-demand patients with long-standing meniscal deficiency and resultant chondral defects are indicated for cartilage restoration and preservation procedures. A meniscal allograft transplantation is indicated in symptomatic patients with prior total or subtotal meniscectomy. It is important to address other concomitant pathology such as instability, alignment, and chondral defects. Concomitant procedures are often performed with meniscal transplants, including osteochondral allograft transplantation for larger defects. Technique Description: This surgical technique video demonstrates a tibial tubercle osteotomy approach to gain access to both the medial and lateral tibiofemoral compartments. An arthroscopic-assisted bone slot technique was performed for meniscal allograft transplantation. Appropriately sized osteochondral allograft bone plugs were then transplanted onto the medial and femoral condyles with a press fit technique. Results: At 1-year follow-up, the presented patient has regained full motion and are back to full activities. Discussion/Conclusion: Full-thickness chondral defects associated with meniscal deficiency in a young, high-demand patient is a difficult problem to manage. Recent results using minimally invasive approaches have demonstrated favorable mid- and long-term outcomes. In patients with pathology that may preclude a minimally invasive approach, an open technique with osteotomy can still have a promising outcome. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Composition, architecture and biomechanical properties of articular cartilage in differently loaded areas of the equine stifle.

Strategies for articular cartilage repair need to take into account topographical differences in tissue composition and architecture to achieve durable functional outcome. These have not yet been investigated in the equine stifle. To analyse the biochemical composition and architecture of three differently loaded areas of the equine stifle. We hypothesise that site differences correlate with the biomechanical characteristics of the cartilage. Ex vivo study. Thirty osteochondral plugs per location were harvested from the lateral trochlear ridge (LTR), the distal intertrochlear groove (DITG) and the medial femoral condyle (MFC). These underwent biochemical, biomechanical and structural analysis. A linear mixed model with location as a fixed factor and horse as a random factor was applied, followed by pair-wise comparisons of estimated means with false discovery rate correction, to test for differences between locations. Correlations between biochemical and biomechanical parameters were tested using Spearman's correlation coefficient. Glycosaminoglycan content was different between all sites (estimated mean [95% confidence interval (CI)] for LTR 75.4 [64.5, 88.2], for intercondylar notch (ICN) 37.3 [31.9, 43.6], for MFC 93.7 [80.1109.6] μg/mg dry weight), as were equilibrium modulus (LTR2.20 [1.96, 2.46], ICN0.48 [0.37, 0.6], MFC1.36 [1.17, 1.56] MPa), dynamic modulus (LTR7.33 [6.54, 8.17], ICN4.38 [3.77, 5.03], MFC5.62 [4.93, 6.36] MPa) and viscosity (LTR7.49 [6.76, 8.26], ICN16.99 [15.88, 18.14], MFC8.7 [7.91,9.5]°). The two weightbearing areas (LTR and MCF) and the non-weightbearing area (ICN) differed in collagen content (LTR 139 [127, 152], ICN176[162, 191], MFC 127[115, 139] μg/mg dry weight), parallelism index and angle of collagen fibres. The strongest correlations were between proteoglycan content and equilibrium modulus (r: 0.642; p: 0.001), dynamic modulus (r: 0.554; p < 0.001) and phase shift (r: -0.675; p < 0.001), and between collagen orientation angle and equilibrium modulus (r: -0.612; p < 0.001), dynamic modulus (r: -0.424; p < 0.001) and phase shift (r: 0.609; p < 0.001). Only a single sample per location was analysed. There were significant differences in cartilage biochemical composition, biomechanics and architecture between the three differently loaded sites. The biochemical and structural composition correlated with the mechanical characteristics. These differences need to be acknowledged by designing cartilage repair strategies.

Raman Spectroscopy and Machine Learning Enables Estimation of Articular Cartilage Structural, Compositional, and Functional Properties.

To differentiate healthy from artificially degraded articular cartilage and estimate its structural, compositional, and functional properties using Raman spectroscopy (RS). Visually normal bovine patellae (n = 12) were used in this study. Osteochondral plugs (n = 60) were prepared and artificially degraded either enzymatically (via Collagenase D or Trypsin) or mechanically (via impact loading or surface abrasion) to induce mild to severe cartilage damage; additionally, control plugs were prepared (n = 12). Raman spectra were acquired from the samples before and after artificial degradation. Afterwards, reference biomechanical properties, proteoglycan (PG) content, collagen orientation, and zonal (%) thickness of the samples were measured. Machine learning models (classifiers and regressors) were then developed to discriminate healthy from degraded cartilage based on their Raman spectra and to predict the aforementioned reference properties. The classifiers accurately categorized healthy and degraded samples (accuracy = 86%), and successfully discerned moderate from severely degraded samples (accuracy = 90%). On the other hand, the regression models estimated cartilage biomechanical properties with reasonable error (≤ 24%), with the lowest error observed in the prediction of instantaneous modulus (12%). With zonal properties, the lowest prediction errors were observed in the deep zone, i.e., PG content (14%), collagen orientation (29%), and zonal thickness (9%). RS is capable of discriminating between healthy and damaged cartilage, and can estimate tissue properties with reasonable errors. These findings demonstrate the clinical potential of RS.

Realignment Surgery for Failed Osteochondral Autologous Transplantation in Osteochondral Lesions of the Talus Associated With Malalignment.

While osteochondral autologous transplantation (OAT) offers favorable results in most patients with osteochondral lesions of the talus (OLT), some patients continue to experience persistent pain following the procedure. Information regarding the etiology of this pain and outcomes of revision surgery are limited. This study aimed to report results of revision surgery with realignment procedures in patients with failed OAT who demonstrated concomitant malalignment at the distal tibia or hindfoot. Eight patients (8 ankles), who had been experiencing persistent pain for more than 1 year following OAT, underwent realignment procedures during revision surgery. All patients underwent primary OAT for the treatment of medial OLTs. Patients were divided into 2 groups based on the main location of deformity: the supramalleolar realignment group (SRG, 5 ankles) and the hindfoot realignment group (HRG, 3 ankles). No direct procedure was performed on the osteochondral lesion at the time of revision surgery. Ankle and hindfoot alignment were evaluated using 6 parameters in weightbearing radiographs. Computed tomography (CT) was used to assess for medial gutter narrowing, spur formation, and cyst volume around transplanted osteochondral plug preoperatively and postoperatively. Clinical outcomes were assessed using Foot Function Index and Visual Analogue Scale. All patients had medial gutter narrowing or spur formation, which are early signs of ankle arthritis. The SRG had varus distal tibial alignment with a median medial distal tibial angle of 85.7 degrees (interquartile range [IQR], 3.2). The HRG had valgus hindfoot alignment and a lower medial longitudinal arch with a median hindfoot moment arm of 8.4 mm (IQR, 6.1) and a median Meary's angle of 11.8 degrees (IQR, 1.4). Spontaneous restoration of the osteochondral lesion was observed after realignment surgery, with cyst volume decreasing from 0.2592 to 0.0873 cm3 (P < .05). Clinical scores improved in all patients. The current study demonstrates the effectiveness of realignment surgery in a selected patient group who experienced persistent pain and showed radiographic evidence of malalignment after primary OAT. Our study provides evidence supporting the use of realignment procedures in these cases, with results indicating improved patient-reported outcomes and spontaneous restoration of osteochondral lesions. Level IV: Case series.