Effectiveness of Lavage Techniques in Removing Immunogenic Elements from Osteochondral Allografts

Comparison of Revision and Primary Osteochondral Allograft Transplantation at Midterm Follow-up: Patient Reported Outcomes, Survivorship, and Reoperation Rates

BACKGROUND

Previous studies have observed promising short-term outcomes after revision osteochondral allograft (OCA) transplantation. However, few studies have examined midterm outcomes after revision OCA transplantation.

PURPOSE

To examine midterm outcomes after revision OCA transplantation of the femoral condyle and evaluate reoperation and survivorship compared with a matched cohort of patients who underwent primary OCA transplantation.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review of prospectively collected data identified patients undergoing revision OCA transplantation to the femoral condyle between 1999 and 2018 (minimum 5-year follow-up). A 1:2 cohort of patients who underwent revision OCA transplantation to patients who underwent primary OCA transplantation, matched by defect size, age, sex, and body mass index, was created. Patient-reported outcome measures and the incidence of reoperations or graft failures were collected. Failure was defined as subchondral collapse of the OCA transplantation as confirmed via second-look arthroscopy, revision OCA transplantation, or conversion to knee arthroplasty.

RESULTS

Fifteen patients who underwent revision OCA transplantation were matched to 30 patients who underwent primary OCA transplantation. The mean follow-up in the revision OCA transplantation group was 9.3 ± 3.0 years (range, 5.1-14.7 years), with a mean age of 31.4 ± 10.0 years (range, 19.9-52.7 years) and a mean body mass index of 25.9 ± 3.4 (range, 20.8-30.4). Revision OCA transplantation was performed to the lateral condyle in 53% of cases (8/15). A concomitant procedure was performed in 73% of patients (11/15), most commonly involving meniscal allograft transplantation (73% [8/11]), followed by realignment osteotomy (27% [3/11]). The Patient Acceptable Symptom State was achieved by a majority of patients who underwent revision OCA transplantation for all patient-reported outcome measures examined (International Knee Documentation Committee, 70%; Lysholm, 83%; Knee injury and Osteoarthritis Outcome Score [KOOS] Pain, 100%; KOOS Symptoms, 70%, KOOS Sport, 90%; KOOS Activities of Daily Living, 80%; KOOS Quality of Life, 80%), and there was no difference in the proportion of patients the Patient Acceptable Symptom State when compared with those undergoing primary OCA transplantation (P≥ .070) (see Table 3). Eight patients (53%) underwent revision OCA transplantation reoperation at a mean time of 3.9 ± 3.7 years (range, 0.6-11.2 years). Failures were observed in 20% (3/15) of patients who underwent revision OCA transplantation at a mean of 4.3 ± 1.9 years (range, 1.7-6.4 years). Graft survivorship free from reoperation (P = .905; revision 53% [8/15], primary 43% [13/30]) and failure (P = .577; revision 13% [2/15], primary 20% [6/30]) was not significantly different between revision and primary groups.

CONCLUSION

High rates of Patient Acceptable Symptom State achievement were observed after revision OCA transplantation. Although limited by sample size, no significant difference in graft survivorship free from failure was appreciated between revision versus primary OCA transplantation groups.

Culturing Osteochondral Explants Under Rotary Shaking or After Removing Bone Marrow Elements Increases Explant Cellular Viability

BACKGROUND

Reduced viability in the deepest zones of osteochondral allografts (OCAs) can weaken the subchondral interface, potentially increasing the risk of failure. This reduction may result from nutritional imbalances due to uneven media distribution or interference from bone marrow elements.

PURPOSE

To investigate whether culturing OCAs using a rotary shaker or removing the bone marrow elements would increase graft cellular viability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bovine osteochondral explants were stored for 28 days at 4°C under 3 different conditions (n = 6 explants per group): static (control group), rotary shaker at 150 rpm (shaker group), and static after removal of bone marrow elements using a Waterpik device (Waterpik group). Chondrocyte viability was assessed using live/dead staining across the entire tissue and in each zone (superficial, middle, deep). Subchondral bone viability was assessed using TUNEL (terminal deoxynucleotidal transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling) staining to detect apoptotic cells.

RESULTS

Both shaker (64.2%; P = .010) and Waterpik (65.6%; P = .005) conditions showed significantly higher chondrocyte viability compared with control (49.8%). When samples were analyzed by zone, the shaker and Waterpik groups displayed higher cellular viability at the middle zone (shaker = 60.6%, P < .001; Waterpik = 56.1%, P < .001) and deep zone (shaker = 63.1%, P = .018; Waterpik = 61.5%, P = .025) than the control group (25.6% at middle zone; 32.8% at deep zone). Additionally, shaker (56.7%; P = .018) and Waterpik (51.4%; P = .007) groups demonstrated a lower percentage of apoptotic cells in subchondral bone compared with control (88.0%). No significant differences were observed between the shaker and Waterpik groups in any of the analyses.

CONCLUSION

Both rotary shaking and removal of bone marrow elements during storage of osteochondral explants led to higher chondrocyte viability at the middle and deep zones of the graft compared with the static storage condition. Enhancing nutrition delivery to the graft could improve its quality, potentially improving outcomes of OCA transplantation.

CLINICAL RELEVANCE

The use of a rotary shaker or the removal of bone marrow elements may significantly improve the culture conditions, increasing graft viability and integrity after OCA storage.

Biomechanical properties of articular cartilage in different regions and sites of the knee joint: acquisition of osteochondral allografts

Osteochondral allograft (OCA) transplantation involves grafting of natural hyaline cartilage and supporting subchondral bone into the cartilage defect area to restore its biomechanical and tissue structure. However, differences in biomechanical properties and donor-host matching may impair the integration of articular cartilage (AC). This study analyzed the biomechanical properties of the AC in different regions of different sites of the knee joint and provided a novel approach to OCA transplantation. Intact stifle joints from skeletally mature pigs were collected from a local abattoir less than 8 h after slaughter. OCAs were collected from different regions of the joints. The patella and the tibial plateau were divided into medial and lateral regions, while the trochlea and femoral condyle were divided into six regions. The OCAs were analyzed and compared for Young's modulus, the compressive modulus, and cartilage thickness. Young's modulus, cartilage thickness, and compressive modulus of OCA were significantly different in different regions of the joints. A negative correlation was observed between Young's modulus and the proportion of the subchondral bone (r =  - 0.4241, P < 0.0001). Cartilage thickness was positively correlated with Young's modulus (r = 0.4473, P < 0.0001) and the compressive modulus (r = 0.3678, P < 0.0001). During OCA transplantation, OCAs should be transplanted in the same regions, or at the closest possible regions to maintain consistency of the biomechanical properties and cartilage thickness of the donor and recipient, to ensure smooth integration with the surrounding tissue. A 7 mm depth achieved a higher Young's modulus, and may represent the ideal length.

Knee Joint Preservation in Tactical Athletes: A Comprehensive Approach Based upon Lesion Location and Restoration of the Osteochondral Unit

The unique physical demands of tactical athletes put immense stress on the knee joint, making these individuals susceptible to injury. In order to ensure operational readiness, management options must restore and preserve the native architecture and minimize downtime, while optimizing functionality. Osteochondral lesions (OCL) of the knee have long been acknowledged as significant sources of knee pain and functional deficits. The management of OCL is predicated on certain injury characteristics, including lesion location and the extent of subchondral disease. Techniques such as marrow stimulation, allograft and autologous chondrocyte implantation are examined in detail, with a focus on their application and suitability in tactical athlete populations. Moreover, the restoration of the osteochondral unit (OCU) is highlighted as a central aspect of knee joint preservation. The discussion encompasses the biomechanical considerations and outcomes associated with various cartilage restoration techniques. Factors influencing procedure selection, including lesion size, location, and patient-specific variables, are thoroughly examined. Additionally, the review underscores the critical role of post-operative rehabilitation and conditioning programs in optimizing outcomes. Strengthening the surrounding musculature, enhancing joint stability, and refining movement patterns are paramount in facilitating the successful integration of preservation procedures. This narrative review aims to provide a comprehensive resource for surgeons, engineers, and sports medicine practitioners engaged in the care of tactical athletes and the field of cartilage restoration. The integration of advanced preservation techniques and tailored rehabilitation protocols offers a promising avenue for sustaining knee joint health and function in this demanding population.

High-Speed Centrifugation Efficiently Removes Immunogenic Elements in Osteochondral Allografts

OBJECTIVES

The current clinical pulse lavage technique for flushing fresh osteochondral allografts (OCAs) to remove immunogenic elements from the subchondral bone is ineffective. This study aimed to identify the optimal method for removing immunogenic elements from OCAs.

METHODS

We examined five methods for the physical removal of immunogenic elements from OCAs from the femoral condyle of porcine knees. We distributed the OCAs randomly into the following seven groups: (1) control, (2) saline, (3) ultrasound, (4) vortex vibration (VV), (5) low-pulse lavage (LPL), (6) high-pulse lavage (HPL), and (7) high-speed centrifugation (HSC). OCAs were evaluated using weight measurement, micro-computed tomography (micro-CT), macroscopic and histological evaluation, DNA quantification, and chondrocyte activity testing. Additionally, the subchondral bone was zoned to assess the bone marrow and nucleated cell contents. One-way ANOVA and paired two-tailed Student's t-test are used for statistical analysis.

RESULTS

Histological evaluation and DNA quantification showed no significant reduction in marrow elements compared to the control group after the OCAs were treated with saline, ultrasound, or VV treatments; however, there was a significant reduction in marrow elements after LPL, HPL, and HSC treatments. Furthermore, HSC more effectively reduced the marrow elements of OCAs in the middle and deep zones compared with LPL (p < 0.0001) and HPL (p < 0.0001). Macroscopic evaluation revealed a significant reduction in blood, lipid, and marrow elements in the subchondral bone after HSC. Micro-CT, histological analyses, and chondrocyte viability results showed that HSC did not damage the subchondral bone and cartilage; however, LPL and HPL may damage the subchondral bone.

CONCLUSION

HSC may play an important role in decreasing immunogenicity and therefore potentially increasing the success of OCA transplantation.

Osteochondral Allografts: Pearls to Maximize Biologic Healing and Clinical Success

We present an evidence-based approach to optimize the biologic incorporation of osteochondral allografts: (1) The donor graft is gradually rewarmed to room temperature to reverse the metabolic suppression from cold storage. (2) The graft is harvested while submerged in saline to limit thermal necrosis. (3) Subchondral bone depth is preferred at 4 to 6 mm depth (total plug depth ∼5-8 mm including articular cartilage) to reduce graft immunogenicity and to promote incorporation. (4) The bone is prepared with grooves/beveling to decrease impaction forces, increase access to subchondral deep zones during preparation, and promote graft-host interface healing. (5) High-pressure pulsed lavage is used to reduce antigenicity by removing marrow elements. (6) Pressurized carbon dioxide following pulsed lavage further reduces marrow elements and improves graft porosity for orthobiologic incorporation. (7) Orthobiologic substances (e.g., concentrated bone marrow aspirate) may enhance incorporation on imaging and result in greater osteogenic potential. (8) A suture is placed behind the graft to facilitate removal and repositioning; atraumatic graft insertion without high impaction forces maintains chondrocyte viability. These evidence-based pearls for osteochondral allograft handling optimize metabolic activity, reduce thermal necrosis, reduce antigenicity with removal of marrow elements, enhance biologic potential, and maintain chondrocyte viability to optimize biologic healing and clinical success.

The Missouri Osteochondral Preservation System Is Associated With Better Short-Term Outcomes Than Standard Preservation Methods When Performing Osteochondral Allograft Transplantation Using Shell Grafts for Patellofemoral Lesions

PURPOSE

To compare outcomes after whole-surface osteochondral allograft (OCA) transplantation using shell grafts for treatment of patellofemoral joint lesions with respect to surfaces treated and OCA preservation method.

METHODS

With institutional review board approval and informed consent, patients were prospectively enrolled into a registry to follow outcomes after OCA transplantation. Patients who received patellofemoral shell OCA to treat the entire articular surface of the patella, trochlea, or both, and with a minimum of 2-year follow-up data, including patient-reported outcome measures (PROMs), failures, and complications, were included. Functional graft survival was determined based on patients returning to functional activities without need for OCA revision or arthroplasty surgery and calculated using the formula: 100% - (%revision + %failure). Minimum clinically important differences were determined based on previously validated data. Outcomes were compared based on differences in graft preservation methodology (Missouri Osteochondral Preservation System [MOPS] or standard preservation [SP]) and based on surfaces treated (patella, trochlea, or both).

RESULTS

Fifty-eight patients met inclusion criteria. Mean age was 36.7 years (range 15-60 years) and mean body mass index was 28.9 (range 18-42). OCAs stored using SP methods were transplanted in 12 patients, mean follow-up was (66.1 months; range 54-70 months): OCAs stored using MOPS methods were transplanted in 46 patients, mean follow-up was (44.8 months; range 24-60 months). Graft survival rate at final follow-up was significantly greater (P = .025) for MOPS OCAs (98%) compared with SP OCAs (75%), whereas 2-year functional graft survival rates (MOPS 98% vs SP 83%; P = .1) were not. Reoperation rate was significantly greater (P = .0014) for SP cases compared with MOPS cases. PROMs showed statistically significant and clinically meaningful improvements through 4 years after unipolar patella, unipolar trochlea, and bipolar patellofemoral OCA transplantation using MOPS grafts. Unipolar patella OCA transplantations were associated with significantly more reduction in pain and significantly better PROMs at 1-year compared with unipolar trochlea and bipolar patellofemoral OCAs.

CONCLUSIONS

OCA transplantation using MOPS shell grafts for unipolar and bipolar patellofemoral resurfacing was associated with statistically significant and clinically meaningful improvements from preoperative levels of pain and function. The 2-year functional graft survival rate was 83% in the SP group and 98% in the MOPS group, such that MOPS was associated with better short-term outcomes than SP methods when performing OCA transplantation using shell grafts for patellofemoral lesions. Patients who received unipolar patella allografts reported the best outcomes in terms of pain and function.

LEVEL OF EVIDENCE

Level III, retrospective analysis of registry data.

Revision Lateral Femoral Condyle Osteochondral Allograft Transplantation With the Snowman Technique After Failed Previous Oblong Osteochondral Allograft

Osteochondral allograft transplantation provides components of both cartilage and subchondral bone and can be used in large and multifocal defects where autologous procedures are limited by donor-site morbidity. Osteochondral allograft transplantation is particularly appealing in the management of failed cartilage repair, as larger defects and subchondral bone involvement are often present, and the use of multiple overlapping plugs might be considered. The described technique provides our preoperative workup and reproducible surgical approach for patients who have undergone previous osteochondral transplantation with graft failure and are young, active patients who would not be otherwise suited for a knee arthroplasty procedure.

Assessment of Outcomes After Multisurface Osteochondral Allograft Transplantations in the Knee

Background

Treatment of multisurface articular cartilage lesions of the knee is a challenging problem.

Hypothesis

Large multisurface cartilage defects in the knee can be successfully managed with transplantation of high chondrocyte viability osteochondral allografts (OCAs) to result in statistically significant improvements in patient-reported outcome measures of pain and function.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients were prospectively enrolled into a registry to follow outcomes after OCA transplantation. The study included patients who received OCA transplantation for multisurface unipolar defects in 1 knee and had minimum 2-year follow-up data, including patient-reported outcome measures, failures, reoperations, and complications. The OCA transplants had been stored using 2 methods: standard preservation (SP) or Missouri Osteochondral Preservation System (MOPS). Preoperative data were compared with outcomes at 1 year and final follow-up, and risk factors for revision surgery or failure (total knee arthroplasty) were analyzed.

Results

The sample included 25 patients with a mean age of 37.2 years (range, 13-51 years), body mass index of 27.7 (range, 18-38), and follow-up of 45.1 months (median, 49 months; range, 24-68 months). OCAs stored using SP were transplanted into 6 patients, and those stored using MOPS were transplanted into 19 patients. The initial success rate was significantly higher for MOPS OCAs (94.7%) than SP OCAs (33.3%). There were statistically significant improvements in all patient-reported outcomes at 1 year and final follow-up in the MOPS cohort (P < .0001 for all). Revision surgery/failure was significantly associated with patients who were nonadherent to the prescribed postoperative restrictions and rehabilitation protocols (P = .038; odds ratio = 13.5) and with OCAs that had a viable chondrocyte density <70% of the established reference range mean at transplantation (P = .0037; odds ratio = 76).

Conclusion

OCA transplantation for treatment of large multisurface cartilage defects in the knee resulted in a 94.7% initial success rate when grafts with high viable chondrocyte density (≥70%) were used and when patients strictly adhered to prescribed postoperative rehabilitation protocols. Successful outcomes were associated with statistically significant improvements in patient-reported outcome measures of pain and function.

Fresh Osteochondral Allograft Transplantation in Osteochondritis Dissecans in the Knee Joint

Osteochondritis dissecans (OCD) is a chronic and painful joint condition that can occur from childhood through to adult life. Microtrauma, vascular insufficiency, or abnormal endochondral ossification are the most common causes of OCD. Reconstructive techniques for OCD of the knee are typically necessary when either non-operative or reparative/regenerative operative treatments fail, or when the OCD is irreversible. To analyze the clinical outcomes and failure rates of fresh osteochondral allograft transplantation (FOCA) used as a reconstructive strategy in OCD patients, an in-depth search was carried out on the PubMed, Scopus, and Web of Science databases concerning the existing evidence related to the use of FOCA for OCD patients in the knee joint. A total of 646 studies were found through the search and 2 studies were added after a cross-referenced examination of the articles within the bibliography. Six studies with a total of 303 OCD lesions treated with FOCA, with a mean follow-up of 6.3 years, were included. Although a limited number of low-level evidence studies on this topic are available in previous research, satisfactory clinical results and survival rates of the reconstruction are reported. However, to better define the real advantages of FOCA in the healing process of OCD lesions, comparative studies with different techniques are needed.

The impact of tourniquet on tibial bone cement penetration in different zones in primary total knee arthroplasty: a meta-analysis

Background

Cement mantle penetration and the cement–bone interface strength were critical to a successful primary total knee arthroplasty (TKA). It remained unclear whether decreased blood and fat in the cancellous bone achieved with the use of a tourniquet increases tibial cement mantle penetration in different zones on AP and lateral view in TKA according to criteria defined by the Knee Society Scoring System (KSS). The purpose of this study was to determine whether tourniquet use influences tibial cement mantle penetration in different zones on AP and lateral view in TKA according to KSS.

Methods

We conducted a meta-analysis to identify studies involving the impact of tourniquet use and no tourniquet use on tibial bone cement penetration in primary TKA in electronic databases, including Web of Science, Embase, PubMed, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CBM, VIP, Wanfang database, up to January 2021. Finally, we identified 1231 patients (1231 knees) assessed in twelve studies.

Results

Tourniquet use increases the cumulative cement mantle penetration (P < 0.00001), mean cement mantle penetration (P = 0.004), and cement mantle in zone 3(P < 0.0001) on AP view. However, there were no significant differences in cement mantle in zone 1(P = 0.5), zone 2(P =0 .54), zone 4(P = 0.07) on AP view, and zone 1(P = 0.32), zone 2(P = 0.38) on lateral view between two groups. There were also no significant differences in length of surgery(P = 0.7), change in hemoglobin(P = 0.4), transfusion rates(P = 0.47), and complications such as muscular calf vein thrombosis(P = 0.21), superficial infection (P = 0.72), and deep vein thrombosis (P = 0.66) between two groups.

Conclusion

The application of a tourniquet increases the thickness of the tibial bone cement penetration—the increase in the thickness of bone cement penetration mainly located in zone 3 on the anteroposterior (AP) view.

Systematic Review of Osteochondral Allograft Transplant Immunology: How We Can Further Optimize Outcomes

Despite the growing success for osteochondral allograft (OCA) transplantation in treating large articular cartilage lesions in multiple joints, associated revision and failure rates are still higher than desired. While immunorejection responses have not been documented, the effects of the host's immune responses on OCA transplantation failures have not been thoroughly characterized. The objective of this study was to systematically review clinically relevant peer-reviewed evidence pertaining to the immunology of OCAs to elucidate theragnostic strategies for improving functional graft survival and outcomes for patients undergoing OCA transplantation. This systematic review of Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, MEDLINE, PubMed, and EMBASE suggests that host immune responses play key roles in incorporation and functional survival of OCA transplants. OCA rejection has not been reported; however, graft integration through creeping substitution is reliant on host immune responses. Prolonged inflammation, diminished osteogenic potential for healing and incorporation, and relative bioburden are mechanisms that may be influenced by the immune system and contribute to undesirable outcomes after OCA transplantation. Based on the safety and efficacy of OCA transplantation and its associated benefits to a large and growing patient population, basic, preclinical, and clinical osteoimmunological studies on OCA transplantation that comprehensively assess and correlate cellular, molecular, histologic, biomechanical, biomarkers, diagnostic imaging, arthroscopic, functional, and patient-reported outcome measures are of high interest and importance.

Changes in knee range of motion after large osteochondral allograft transplantations

BACKGROUND

Our study purpose was to determine if primary osteochondral allograft (OCA) transplant surgeries for large (>4 cm²) single-surface, multisurface, or bipolar articular defects in the knee would be associated with significant gains in knee range of motion (ROM) at ≥1-year follow-up when compared to preoperative ROM.

METHODS

Patients were prospectively enrolled into a dedicated registry to follow outcomes after OCA with or without meniscal allograft transplantation using Missouri Osteochondral Preservation System (MOPS)-preserved allografts. Patients were included if they had surgery to repair at least one osteochondral defect, and when at least one year of ROM data and Visual Analog Scale pain scores were available. Data on complications and reoperations, patient-reported outcome measures, compliance with rehabilitation, revisions, or failures were recorded.

RESULTS

For patients who met inclusion criteria after OCA surgery (n = 75), overall ROM increased from 127.8 ± 17 degrees preoperatively, to 130.5 ± 14 post-operatively. Non-compliance was the largest factor contributing to postoperative ROM lag or loss. Knee manipulation/lysis of adhesion rates were comparable to rates in TKA and ACL procedures (2.96-4.54% for ACL/TKA, 4% for OCAs in the present study).

CONCLUSION

Results suggest that OCA with or without meniscal allograft transplantation in the knee using high-viability grafts, advanced graft cutting and implantation techniques, and procedure-specific rehabilitation protocols can result in consistently successful outcomes in a high percentage (92%) of selected patients. Most patients (95%) can expect to regain, or improve, to "full" functional range of motion (130°) at 1 year after surgery such that highly functional activities can be performed.

LEVEL OF EVIDENCE

Cohort study; Level III.

Prospective Assessment of Outcomes After Primary Unipolar, Multisurface, and Bipolar Osteochondral Allograft Transplantations in the Knee: A Comparison of 2 Preservation Methods

BACKGROUND

Articular cartilage lesions in the knee remain a challenging clinical problem.

HYPOTHESIS

A novel graft preservation method combined with surgical technique and patient management improvements would lead to consistently successful outcomes after osteochondral allograft (OCA) transplantation.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

With institutional review board approval and informed consent, patients were prospectively enrolled into a registry to follow outcomes after OCA transplantation. Patients were included when ≥1-year follow-up data were available, including complications and reoperations, patient-reported outcome measures (PROMs), compliance with rehabilitation, revisions, and failures.

RESULTS

For patients meeting inclusion criteria (N = 194), mean ± SD age was 37.9 ± 12.2 years and mean BMI was 28.9 ± 5; 38% received unipolar transplants (44% multisurface) and 62% received bipolar transplants. OCAs were preserved by standard tissue bank methods (standard preservation [SP]; 29%) or the novel method (Missouri Osteochondral Preservation System [MOPS]; 71%). Initial success rates were 79% for all cases combined, 60% for SP, and 84% for MOPS. MOPS cases were significantly (P = .028) more likely to be associated with successful outcomes when compared with SP cases. PROMs improved significantly (P < .05) for all cohorts through 3 to 4 years of follow-up. Revisions were performed in 19 cases (10%). MOPS grafts were associated with a significantly (P = .0014) lower revision rate (5%) than SP grafts (21%). Failures occurred in 26 patients (13%), with all undergoing total knee arthroplasty. Bipolar cases were significantly (P = .008) more likely to be associated with failure. MOPS grafts were associated with a significantly (P = .048) lower failure rate (11%) than were SP grafts (19%). Noncompliance with the prescribed rehabilitation protocol was significantly (P = .00008) more likely to be associated with failure.

CONCLUSION

Prospective data for 194 cases revealed that OCA transplantation for unipolar, multisurface, and bipolar cartilage restoration can be associated with consistently successful outcomes. The 5% revision rate, 11% failure rate, 82%-94% survival probability estimates, and continually improving PROMs through postoperative 3 to 4 years underscore major advances in outcomes as compared with previous reports. These encouraging results were realized with the use of a novel graft preservation method; autogenous bone marrow concentrate pretreatment of donor bone; advancements in graft cutting, implantation, and stabilization techniques; and procedure-specific rehabilitation protocols.

An Expert Consensus Statement on the Management of Large Chondral and Osteochondral Defects in the Patellofemoral Joint

Background

Cartilage lesions of the patellofemoral joint constitute a frequent abnormality. Patellofemoral conditions are challenging to treat because of complex biomechanics and morphology.

Purpose

To develop a consensus statement on the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint using a modified Delphi technique.

Study Design

Consensus statement.

Methods

A working group of 4 persons generated a list of statements related to the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint to form the basis of an initial survey for rating by a group of experts. The Metrics of Osteochondral Allografts (MOCA) expert group (composed of 28 high-volume cartilage experts) was surveyed on 3 occasions to establish a consensus on the statements. In addition to assessing agreement for each included statement, experts were invited to propose additional statements for inclusion or to suggest modifications of existing statements with each round. Predefined criteria were used to refine statement lists after each survey round. Statements reaching a consensus in round 3 were included within the final consensus document.

Results

A total of 28 experts (100% response rate) completed 3 rounds of surveys. After 3 rounds, 36 statements achieved a consensus, with over 75% agreement and less than 20% disagreement. A consensus was reached in 100.00% of the statements relating to functional anatomy of the patellofemoral joint, 88.24% relating to surgical indications, 100.00% relating to surgical technical aspects, and 100.00% relating to rehabilitation, with an overall consensus of 95.5%.

Conclusion

This study established a strong expert consensus document relating to the functional anatomy, surgical indications, donor graft considerations for osteochondral allografts, surgical technical aspects, and rehabilitation concepts for the management of large chondral and osteochondral defects in the patellofemoral joint. Further research is required to clinically validate the established consensus statements and better understand the precise indications for surgery as well as which techniques and graft processing/preparation methods should be used based on patient- and lesion-specific factors.

Pulse Lavage Fails to Significantly Reduce Bone Marrow Content in Osteochondral Allografts: A Histological and DNA Quantification Study

BACKGROUND

Current clinical practice calls for pulse lavage of fresh osteochondral allografts (OCAs) to reduce immunogenicity; however, there is limited evidence of its effectiveness in reducing allogenic bone marrow elements.

PURPOSE

To evaluate the effectiveness of pulse lavage in removing marrow elements from trabecular bone in fresh OCA transplantation.

STUDY DESIGN

Controlled laboratory study.

METHODS

The authors evaluated 48 fresh OCA plugs with 4 different common sizes (14- and 24-mm diameter, 6- and 10-mm thickness). Within each size group, half of the samples underwent pulse lavage (n = 6) with saline solution and half were left untreated (no lavage; control group, n = 6). For each treatment and size group, 3 samples were analyzed for DNA content as an indicator of the number of residual nucleated cells; the other 3 samples were histologically analyzed to assess the presence and distribution of cells within subchondral bone pores in 3 specific locations within the plug: peripheral, intermediate, and core.

RESULTS

Osteochondral plugs treated with pulse lavage did not show a significant decrease in DNA content in comparison with untreated plugs. Overall, histological analysis did not show a significant difference between the treated and untreated groups (P = .23). Subgroup analysis by size demonstrated decreased marrow content in treated versus untreated groups in the thinner plug sizes (14 × 6 mm and 24 × 6 mm). Histological evaluation by zone demonstrated a significant difference between groups only in the peripheral zone (P = .04).

CONCLUSION

Pulse lavage has limited effectiveness in removing marrow elements, in particular in plugs that are larger in diameter and, more importantly, in thickness. Better techniques for subchondral bone treatment are required for more thorough removal of potentially immunogenic marrow elements.

CLINICAL RELEVANCE

OCA transplantation has become an established treatment modality. Unfortunately, OCA is not without limitations, chiefly its mode of failure through inadequate integration of the allograft subchondral bone with subsequent collapse. In an effort to improve integration, current clinical practice calls for pulse lavage to remove allogenic bone marrow from the subchondral bone in hopes of decreasing the immunogenicity of the graft and facilitating revascularization.

The Effect of Tourniquet Use and Sterile Carbon Dioxide Gas Bone Preparation on Cement Penetration in Primary Total Knee Arthroplasty

BACKGROUND

Tourniquetless total knee arthroplasty (TKA) is experiencing resurgence in popularity due to potential pain control benefits. Furthermore, optimal cement technique and implant fixation remain paramount to long-term cemented TKA success, as aseptic loosening continues to be a leading cause of revision. The purpose of this study is to determine how tourniquet use and/or novel bone preparation using sterile, compressed carbon dioxide (CO₂) gas affected cement penetration in TKA.

METHODS

A retrospective review was performed on 303 consecutive primary TKAs with the same implant in 3 groups: (1) a tourniquet without sterile CO₂ compressed gas used for bone preparation, (2) no tourniquet with CO₂ gas, and (3) tourniquet use and CO₂ gas bone preparation. Cement penetration was measured on radiographs by two independent, blinded raters across 7 zones defined by the Knee Society Radiographic Evaluation System.

RESULTS

The 3 groups did not differ on age, body mass index, or gender (P ≥ .1). Cement penetration was greater in 6 of 7 zones with significantly greater cement penetration in 3 zones (tibial anteroposterior zone 2, femoral lateral zones 3A and 3P) in groups that utilized CO₂ gas bone preparation compared to the tourniquet only group (P ≤ .039).

CONCLUSION

Bone prepared with CO₂ gas showed significantly more cement penetration in 3 zones with greater cancellous bone. The results suggest that use of CO₂ gas bone preparation may achieve greater cement penetration than using a tourniquet with lavage only.

Treatment of unstable knee osteochondritis dissecans in the young adult: results and limitations of surgical strategies-The advantages of allografts to address an osteochondral challenge

Joint surface incongruence resulting from osteochondritis dissecans (OCD) alters the articular physiologic congruence, increasing the contact stress on adjacent joint surfaces and accelerating wear and the cascade of joint degeneration. Accordingly, the restoration of articular surface integrity is of major importance, especially in young adults where, in lesions left untreated or following simple fragment excision, early osteoarthritis can be anticipated. Therefore, the treatment algorithm in unstable knee OCD of the young adult foresees surgical options to restore the articular surface. Several procedures have been proposed, including refixation of the detached fragment bone marrow stimulation, osteochondral autograft implantation, fresh osteochondral allograft transplantation, and cell-based or cell-free regenerative techniques. The aim of this review was to summarize the evidence for these surgical strategies, reporting their results and limitations. The overall evidence documents positive results for each of the assorted surgical procedures applied to treat unstable OCD, thus indicating support for their selected use to treat osteochondral defects paying particular attention to their specific indications for the lesion characteristics. The fixation of a good quality fragment should be pursued as a first option, while unfixable small lesions may benefit from autografts. For large lesions, available cell-based or cell-free osteochondral scaffold are a feasible solution but with limitation in terms of regenerated tissue quality. In this light, fresh allografts may offer articular surface restoration with viable physiologic osteochondral tissue providing a predictably successful outcome, and therefore they may currently represent the most suitable option to treat unstable irreparable OCD lesion in young adults. LEVEL OF EVIDENCE: V.

Patellofemoral Cartilage Repair

Purpose of Review

This review provides an overview of well-established and newly developed cartilage repair techniques for cartilage defects in the patellofemoral joint (PFJ). An algorithm will be presented for approaching cartilage defects considering the distinct anatomy of both the patellar and trochlear articular surfaces.

Recent Findings

Recent studies on cartilage repair in the PFJ have demonstrated improved outcomes in an attempt to delay or obviate the need for arthroplasty, and improve symptoms in young patients. While autologous chondrocyte implantation shows good and excellent outcomes for chondral lesions, osteochondral defects are adequately addressed with osteochondral allograft transplantation. In case of patellar malalignment, concomitant tibial tubercle osteotomy can significantly improve outcomes. Particulated cartilage and bone marrow aspirate concentrate are potential new alternative treatments for cartilage repair, currently in early clinical studies.

Summary

Due to the frequency of concomitant anatomic abnormalities in the PFJ, a thorough clinical examination combined with careful indication for each procedure in each individual patient combined with meticulous surgical technique is central to achieve satisfying outcomes. Additional comparative studies of cartilage repair procedures, as well as investigation of newer techniques, are needed.

Fresh Osteochondral Allograft Transplantation for Focal Chondral Defect of the Humerus Associated With Anchor Arthropathy and Failed SLAP Repair

Isolated, full-thickness articular cartilage lesions of the glenohumeral joint can cause pain, mechanical symptoms, and impaired function. Reports on operative management of these injuries with arthroscopic techniques, such as marrow stimulation, have shown improvement in patient symptoms. In cases where the subchondral bone is involved, osteochondral allograft (OCA) transplantation has shown positive results for contained, focal cartilage defects. The technique for OCA transplantation to treat Hill-Sachs lesions has been reported in detail, and there are multiple case series reporting on the outcomes of OCA used for this purpose. This Technical Note shows the application of OCA to treat a case of anchor arthropathy where a glenoid anchor placed during arthroscopic stabilization causes iatrogenic damage to the humeral head. This type of injury can result in cartilage lesions in uncommon locations, such as on the posterior humeral head. In this description, the technical pearls and pitfalls of managing difficult-to-access posterior humeral head lesions are presented along with the senior authors' general technique for OCA to treat focal lesions of the humeral head cartilage.