Osteochondral autograft transplantation in the elbow

Surgical approaches to the capitellum: a comparative anatomic study

BACKGROUND

Osteochondritis dissecans (OCD) of the humeral capitellum is an important cause of elbow disability in young athletes. Large and unstable lesions sometimes require joint reconstruction with osteochondral autograft. Several approaches have been described to expose the capitellum for the purpose of treating OCD. The posterior anconeus-splitting approach and the lateral approach with or without release of the lateral ligamentous complex are the most frequently used for this indication. The surface accessible by these approaches has not been widely studied. This study compared the extent of the articular surface of the capitellum that could be exposed with the Kocher approach (without ligament release) vs. the posterior anconeus-splitting approach. A secondary outcome was the measurement of any additional area that could be reached with lateral ulnar collateral ligament release (Wrightington approach).

METHODS

The 3 approaches were performed on 8 adult cadaveric elbows: first, the Kocher approach; then, the anconeus-splitting approach; and finally, the Wrightington approach. The visible articular surface was marked out after completion of each approach.

RESULTS

The mean articular surface of the capitellum was 708 mm2 (range, 573-830 mm2). The mean visible articular surface was 49% (range, 43%-60%) of the total surface with the Kocher approach, 74% (range, 61%-90%) with the posterior anconeus-splitting approach, and 93% (range, 91%-97%) with the Wrightington approach. Although the Kocher approach provided access to the anterior part of the capitellum, the anconeus-splitting approach showed adequate exposure to the posterior three-quarters of the articular surface and overlapped the most posterior part of the Kocher approach. A combination of the 2 lateral ulnar collateral ligament-preserving approaches allowed access to 100% of the joint surface.

CONCLUSION

Most OCD lesions are located in the posterior area of the capitellum and can therefore be reached with the anconeus-splitting approach. When OCD lesions are located anteriorly, the Kocher approach without ligament release is efficient. A combination of these 2 approaches enabled the entirety of the joint surface to be viewed.

Preoperative Evaluation and Surgical Simulation for Osteochondritis Dissecans of the Elbow Using Three-Dimensional MRI-CT Image Fusion Images

We used our novel three-dimensional magnetic resonance imaging-computed tomography fusion images (3D MRI-CT fusion images; MCFIs) for detailed preoperative lesion evaluation and surgical simulation in osteochondritis dissecans (OCD) of the elbow. Herein, we introduce our procedure and report the findings of the assessment of its utility. We enrolled 16 men (mean age: 14.0 years) and performed preoperative MRI using 7 kg axial traction with a 3-Tesla imager and CT. Three-dimensional-MRI models of the humerus and articular cartilage and a 3D-CT model of the humerus were constructed. We created MCFIs using both models. We validated the findings obtained from the MCFIs and intraoperative findings using the following items: articular cartilage fissures and defects, articular surface deformities, vertical and horizontal lesion diameters, the International Cartilage Repair Society (ICRS) classification, and surgical procedures. The MCFIs accurately reproduced the lesions and correctly matched the ICRS classification in 93.5% of cases. Surgery was performed as simulated in all cases. Preoperatively measured lesion diameters exhibited no significant differences compared to the intraoperative measurements. MCFIs were useful in the evaluation of OCD lesions and detailed preoperative surgical simulation through accurate reproduction of 3D structural details of the lesions.

Outcomes of Osteochondral Autograft Transplantation in Pediatric Patients With Osteochondritis Dissecans of the Capitellum

PURPOSE

To assess the outcomes of osteochondral autograft transplantations in the treatment of osteochondritis dissecans of the capitellum in the pediatric population.

METHODS

Between 2011 and 2016, 15 patients who had undergone osteochondral autograft transplantation at a mean age of 13.7 years at surgery were identified. The donor site was from the superolateral, non-weight-bearing surface of the lateral femoral condyle of the ipsilateral knee.

RESULTS

Mean follow-up was 29.5 months, with no patients lost to follow-up. Mean arc of motion increased significantly from 121.9° preoperatively to 139.1° postoperatively. All 9 elite athletes returned to sports at an elite level: 7 returned to the same level of competition in the same sport, 1 retired from gymnastics due to multiple injuries but began diving at an elite level, and 1 retired from baseball unrelated to elbow symptoms but continued hockey at the same level. Of the 4 recreational athletes, all returned to sport. There were no intraoperative complications. The symptoms resolved completely in all but 2 patients, who improved over their preoperative condition. The donor site knee pain resolved in all patients at an average of 2.3 months. Postoperative imaging demonstrated the healing and incorporation of the plug in all patients.

CONCLUSIONS

In the treatment of osteochondritis dissecans of the capitellum, osteochondral autograft transplantation demonstrates excellent clinical and radiographic outcomes, with minimal short-term donor site morbidity and a high level of return to the sport.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Osteochondral Autograft Transplantation for Capitellar Osteochondritis Dissecans

Background

The goal of the osteochondral autograft transplantation (OAT) procedure is to replace both the bone and cartilage that have been compromised by osteonecrosis of the capitellum, a condition known as osteochondritis dissecans (OCD). In children, the vascularity of the capitellum is limited compared with that in adults because the physis acts as a physical barrier to vascular ingrowth from the metaphysis to the epiphysis. The necrotic subchondral bone cannot keep up with the weight-bearing demands of certain high-level athletes such as gymnasts, accumulating microfractures and eventually crumbling. Without the support of the subchondral bone, the overlying cartilage fractures and eventually comes loose, often floating around the joint as a loose body. Fibrocartilage may form to fill the void left behind but cannot restore either the structural integrity of the bone or the gliding and compressive properties of hyaline cartilage. Replacement of both the bone and the cartilage requires an osteochondral transplant. Fortunately, there are regions of the articular surface of the knee in which there is minimal load or contact and that are therefore expendable as donor osteochondral plugs. We prefer a single-plug technique whenever possible because it is easier to perform and only requires union of the plug to native bone across 1 interface. If a single plug will not cover the defect or cannot be made to match the contour of the capitellum, multiple plugs may be used (i.e., mosaicplasty).

Description

Place the patient with the operative side up in the lateral decubitus position with the arm in a holder. First, perform a diagnostic elbow arthroscopy. Use the proximal anteromedial portal to insert the scope across the front of the joint. Using a switching stick, make an anterolateral portal. Place a cannula to prevent having to go in and out of the joint multiple times, as this increases the risk of neurologic injury. Perform a synovectomy if necessary and remove any loose bodies. The absence of synovitis is a sign that the lesion has likely healed. Inspect the capitellum and radial head. The anterior margin of the OCD lesion of the capitellum will be barely visible as the joint is brought to extension.If the lesion is readily visible in the anterior compartment, the lesion will be too anterior to approach from an anconeus split approach. In this case, some have advocated a takedown of the lateral collateral ligament to aid in visualization from a lateral approach¹. We have had good success with a direct anterior approach between the brachialis and brachioradialis, mobilizing the radial nerve laterally.If the chondral injury is extensive or includes the articular surface of the radial head, then the injury is too advanced to successfully treat with an OAT procedure. In these cases, we perform an interposition arthroplasty of the radiocapitellar joint. Radial head resection is not an option in a child because of the high risk of proximal radial migration. Radial head replacement likewise is not an option because of the high risk of failure.Switch the viewing and working portals again with use of switching sticks and repeat the process for the medial side of the joint. Make a direct posterior and a proximal posterolateral portal. Never debride on or near the medial gutter because the ulnar nerve is immediately adjacent. Establish a soft spot portal and place the scope through it. Loose bodies and extensive synovitis are typically seen in this area when the soft spot portal is used as a viewing portal. The OCD lesion should be visible through the soft spot portal. If the lesion is not readily visible with some elbow flexion, then the lesion is probably too anterior for an anconeus split approach and an anterior approach should be considered.Challenge the lesion with a probe. If the cartilage is damaged but the subchondral bone holds firm, perform a microfracture technique. If the cartilage is soft or unstable and the underlying bone is compromised, perform an OAT procedure. In the majority of cases in which the lesion is accessible posteriorly, connect the proximal posterolateral portal and the soft spot portal and split the anconeus. The lesion will be visible in deep flexion. There are several options for instrumentation from multiple manufacturers that each have their own advantages and disadvantages. Using a recipient harvester, remove the diseased bone and cartilage to a stable rim, keeping the harvester as perpendicular to the surface as possible.At the knee, make a 3-cm transverse incision directly over the superolateral corner of the lateral femoral condyle. Harvest an appropriately sized plug from the superolateral corner of the articular surface. Inspect the plug because it will often be slightly thicker on one side. Rotate the plug to match the contour of the defect in the capitellum. Mallet the donor plug into the recipient deficit with gentle taps, using as few taps as possible to limit chondrocyte injury. Fill the defect in the knee with your choice of bone substitute. Close both wounds in layers.

Alternatives

Other options include allograft plugs, periosteal resurfacing, bone grafting, retrograde and antegrade drilling, and observation.

Rationale

The OCD lesion involves both bone and cartilage. There is now ample evidence that replacing both as a unit yields the best outcomes.

Expected Outcomes

Approximately 90% of patients will return to sports participation, and 80% of patients can expect to return to sport at their previous level of participation^1-3.

Important Tips

A diagnostic arthroscopy confirms the need for the OAT procedure and identifies other pathologies.Remove all of the diseased bone with the recipient harvester.Match the size and contour of the lesion as closely as possible with the plug.Immobilize the elbow in a cast for 4 weeks.

Evaluation and management of elbow injuries in the adolescent overhead athlete

With an increased interest in youth sports, the burden of overhead throwing elbow injuries accompanying early single-sport focus has steadily risen. During the overhead throwing motion, valgus torque can reach and surpass Newton meters (N m) during the late cocking and early acceleration phases, which exceeds the tensile strength (22.7–33 N m) of the ulnar collateral ligament. While the ulnar collateral ligament serves as the primary valgus stabilizer between and degrees of elbow flexion, other structures about the elbow must contribute to stability during throwing. Depending on an athlete’s stage of skeletal maturity, certain patterns of injury are observed with mechanical failures resulting from increased medial laxity, lateral-sided compression, and posterior extension shearing forces. Together, these injury patterns represent a wide range of conditions that arise from valgus extension overload. The purpose of this article is to review common pathologies observed in the adolescent overhead throwing athlete in the context of functional anatomy, osseous development, and throwing mechanics. Operative and non-operative management and their associated outcomes will be discussed for these injuries.

A novel three-dimensional MRI-CT image fusion technique for precise preoperative evaluation and treatment of capitellar osteochondritis dissecans

OBJECTIVES

We developed a novel method to create three-dimensional magnetic resonance imaging-CT (3D MRI-CT) fusion images for detailed lesion evaluation and surgical simulation in capitellar osteochondritis dissecans (COCD). This study aimed to clarify its usefulness.

METHODS

We enrolled 12 boys with COCD (mean age, 13.8 years) and preoperatively constructed 3D models of the humerus and articular cartilage from MR images obtained with a 3-T imager. For better visualization of the articular cartilage outline, we applied 7 kg of axial traction to the elbow during MRI. We also constructed a 3D model of the humerus from CT images. 3D MRI-CT fusion images were created using both models. The average distance difference between two corresponding points as per the 3D CT and 3D MRI models of the humerus was evaluated. Using the 3D MRI-CT fusion images, we measured longitudinal and transverse lesion diameters; evaluated articular cartilage fissures and defects, articular surface deformities, and the International Cartilage Repair Society (ICRS) classification; and validated the results using intraoperative findings.

RESULTS

The mean average distance difference was 0.75 mm. The 3D MRI-CT fusion images accurately reproduced lesion conditions in every case and correctly predicted the ICRS classification with 100% accuracy. Preoperatively measured longitudinal and transverse lesion diameters were not significantly different from intraoperative measurements (p = 0.79, 0.32 respectively).

CONCLUSION

3D MRI-CT fusion images provide a detailed evaluation of COCD lesion severity by presenting the exact positional relationship between the articular cartilage and subchondral bone.

KEY POINTS

• We developed a novel method to create three-dimensional magnetic resonance imaging-computed tomography (3D MRI-CT) fusion images for the evaluation of capitellar osteochondritis dissecans. • 3D MRI-CT fusion images enabled the accurate prediction of lesions and provided a detailed evaluation of lesion severity by presenting the exact positional relationship between the articular cartilage and subchondral bone.

Early Results of Single-plug Autologous Osteochondral Grafting for Osteochondritis Dissecans of the Capitellum in Adolescents

BACKGROUND

Osteochondral autologous transplantation surgery (OATS) has been advocated for unstable osetochondritis dissecans (OCD) lesions of the adolescent capitellum, though limited information is available regarding clinical and radiographic results in North American patients. We hypothesize that single-plug OATS is safe and effective in alleviating pain and restoring function in unstable OCD.

METHODS

Twenty-eight patients with unstable OCD treated with single-plug OATS were evaluated. Mean age at surgery was 14.2 years; there were 14 males. Etiology of OCD was presumed to be sports participation, including baseball (n=5) and gymnastics (n=11). Indications for surgery included unstable, deep OCD lesions; 2 lesions were uncontained, and 3 patients (11%) had OATS after failed prior surgery. OATS was performed by an anconeus muscle-splitting approach; donor grafts were harvested from the lateral femoral condyle by small arthrotomy. Functional outcomes were quantified using the Timmerman instrument. Median clinical and radiographic follow-up was 6.3 months (range, 5.0 to 27.0 mo) and 5.7 months (range, 5.0 to 26.7 mo), respectively. Furthermore, all patients returned functional questionnaires at a median of 9 months postoperatively (range, 5 to 27 mo).

RESULTS

Of the 26 patients who reported preoperative tenderness, 19 (73%) patients had no tenderness at most recent clinical follow-up (P=0.02). Of 18 patients with restricted elbow motion preoperatively, 13 had achieved full range of motion (P=0.10). Both elbow flexion and extension improved significantly [flexion: median change (interquartile range)=10 degrees (0 to 10 degrees), P=0.009; extension: 0 degree (-5 to 0 degrees), P <0.001). On postoperative magnetic resonance imaging, 86% (P<0.001) of elbows had restoration of articular congruity and 93% had complete graft incorporation. Objective [median change (interquartile range)=5 degrees (0 to 15 degrees)], subjective [25 degrees (15 to 40 degrees)], and overall [35 degrees (15 to 45 degrees)] Timmerman scores improved significantly (P=0.001, <0.001, and <0.001, respectively). Of the 13 patients with >6 months follow-up, 9 patients (69%) had returned to their primary sport (P=0.27) and 100% had returned to general sports participation. There were no postoperative complications. At final follow-up, all donor knees were asymptomatic with full motion and strength.

CONCLUSION

Single-plug OATS is safe and effective in improving pain and elbow function in adolescents with unstable OCD, with high return to sports rates and little donor-site morbidity.

LEVEL OF EVIDENCE

Level IV-case series.

Osteochondritis dissecans lesions of the capitellum in overhead athletes: a review of current evidence and proposed treatment algorithm

PURPOSE OF THE REVIEW

To review the most recent literature on osteochondritis dissecans (OCD) lesions of the capitellum in overhead athletes and describe a treatment algorithm based on current best evidence and surgeon experience.

RECENT FINDINGS

Recent research has included larger cohort studies with longer follow-up as well as quality systematic reviews and meta-analyses. These studies have focused on understanding how lesion characteristics such as size, location, and appearance on advanced imaging can predict treatment success. Current literature continues to support nonoperative management for stable lesions. Operative intervention is generally required for unstable lesions and treatment strategies are largely dictated by lesion size and location: debridement or reparative techniques for small lesions while larger lesions or those in high-stress locations are better served by bone and/or cartilage restoration procedures. There has been a rising interest in the use of allograft materials and cell-based therapies. Overhead athletes are uniquely predisposed to capitellar OCD due to the nature of forces applied to the radiocapitellar joint during repeated activity in the overhead position. Despite improvements in operative techniques, successful use of alternative graft materials, and a better understanding of how lesion characteristics influence results, there is still much to learn about this challenging disorder. Future research should focus on comparing operative techniques, refining their indications, and further developing a reliable treatment algorithm that best serves the overhead athlete.

A matched quantitative computed tomography analysis of 3 surgical approaches for osteochondral reconstruction of the capitellum

BACKGROUND

The location of capitellar osteochondritis dissecans (OCD) lesions in the sagittal plane guides the surgical approach used for autologous osteochondral transplantation. We sought to compare the capitellar region accessible for orthogonal graft placement through 3 approaches: (1) posterior anconeus-split approach; (2) lateral approach with lateral collateral ligament (LCL) preservation (LCL-preserving lateral approach); and (3) lateral approach with LCL release (LCL-sacrificing lateral approach).

METHODS

The 3 approaches were sequentially performed on 9 cadaveric elbows: posterior anconeus-split approach, LCL-preserving lateral approach, and LCL-releasing lateral approach. The extent of perpendicular access was delineated with Kirschner wires. Each specimen underwent computed tomography. The accessible region was quantified as degrees on the capitellum and converted into time on a clock, where 0° corresponds to the 12-o'clock position. Generalized estimating equation modeling was used to investigate for significant within-specimen, between-approach differences.

RESULTS

The LCL-preserving and LCL-sacrificing lateral approaches provided more anterior perpendicular access than the posterior anconeus-split approach (mean, 0° vs 83°; P < .001). The posterior anconeus-split approach provided more posterior perpendicular access (mean, 215.0°; P < .001) than the LCL-preserving (mean, 117°; P < .001) and LCL-sacrificing (mean, 145°; P < .001) lateral approaches. The LCL-sacrificing lateral approach provided more posterior exposure than the LCL-preserving lateral approach (mean, 145° vs 117°; P < .001). The mean arc of visualization was greater for the LCL-sacrificing lateral approach than for the LCL-preserving lateral approach (145° vs 117°, P < .001).

CONCLUSIONS

A capitellar OCD lesion can be perpendicularly accessed from a posterior anconeus-split approach if it is posterior to 83° (2:46 clock-face position). A laterally based approach may be required for lesions anterior to this threshold. These data inform clinical decisions regarding the appropriate surgical approach for any OCD lesion.

Visualization of the Capitellum During Elbow Arthroscopy: A Comparison of 3 Portal Techniques

Background:

Capitellar osteochondritis dissecans (OCD) is a debilitating condition of unknown etiology for which various arthroscopic treatments are available. Prior data suggest that greater than 75% of the capitellum can be visualized arthroscopically through a dual lateral portal approach. However, there is no literature assessing arthroscopic visualization of the capitellum via alternative portals.

Purpose:

To determine the percentage of capitellum visualized using the dual lateral, distal ulnar and soft spot, and posterolateral and soft spot portal configurations in a cadaver model.

Study Design:

Descriptive laboratory study.

Methods:

Arthroscopy was performed on 12 fresh-frozen cadaver elbows, 4 for each of the following approaches: dual lateral, distal ulna, and posterolateral. Electrocautery was used to mark the most anterior, posterior, medial, and lateral points seen on the capitellum. The radiocapitellar joint was subsequently exposed through an extensile posterior dissection, and the surface anatomy was reconstructed using the Microscribe 3D digitizing system. Using Rhinoceros software, the percentage of capitellum surface area visualized by each approach was determined.

Results:

The mean percentage of capitellum visualized for the dual lateral, distal ulna, and posterolateral approaches was approximately 68.8%, 66.3%, and 63.5%, respectively. There was no significant difference between the percentage of capitellum seen among approaches (P = .68). On average, 66.5% of the capitellum was visible through these 3 arthroscopic approaches to the elbow.

Conclusion:

Approximately 66.5% of the capitellum is visualized through the popularized posterior arthroscopic portals, with no significant differences found between the 3 investigated approaches.

Clinical Relevance:

As determined in this cadaveric model investigation, each portal technique provides equivalent visualization for capitellar OCD pathology.

Return to Play After Osteochondral Autograft Transplantation of the Capitellum: A Systematic Review

PURPOSE

To determine the rate of return to play and to identify lesion or osteochondral graft characteristics that may influence the return to competitive athletics after osteochondral autograft transplantation (OAT) for symptomatic osteochondritis dissecans (OCD) lesions.

METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A duplicate search of PubMed, Embase, Scopus, Web of Science, and CENTRAL databases was performed, beginning from the database inception dates through July 2016, for all articles evaluating the return to play after OAT for OCD lesions of the capitellum. A methodological quality assessment was completed for all included studies. Patient demographics, osteochondral lesion and graft characteristics, the number of patients, and timing of return to competitive activity were collected and evaluated. Association between graft size/number, the time to osseous healing, and return to sport was evaluated.

RESULTS

Seven articles met the inclusion criteria. All included studies were case series of moderate quality with a mean Methodological Index for Non-Randomized Studies score of 12/16. Overall, 94% (119/126) of patients undergoing OAT for OCD lesions of the capitellum successfully returned to competitive sports. The mean reported time for unrestricted return to athletic competition after OAT was 5.6 months (range, 3-14 months).

CONCLUSIONS

Current best evidence suggests that OAT is successful in treating advanced OCD lesions of the capitellum and returning athletes to high-level competition. Evidence supporting the association between the size and number of grafts used and the time to osseous healing and return to sport is currently limited. Our assessment of the time to return to athletic competition was limited because of variable surgical technique, postoperative rehabilitation protocols, and outcome assessment.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Current Concepts: Osteochondritis Dissecans of the Capitellum and the Role of Osteochondral Autograft Transplantation

Background: Osteochondritis dissecans (OCD) of the capitellum is a painful condition, which often affects young throwing athletes. Our current understanding regarding the etiology, risks factors, diagnosis, and efficacy of the available treatment options has expanded over recent years, however remains suboptimal. Recent data on patient-reported outcomes following osteochondral autograft transplantation (OAT) for the treatment of large osteochondral lesions of the capitellum have been promising but limited. This review seeks to critically analyze and summarize the available literature on the etiology, diagnosis, and reported outcomes associated with OCD of the capitellum and the use of OAT for its treatment. Methods: A comprehensive literature search was conducted. Unique and customized search strategies were formulated in PubMed, Embase, Scopus, Web of Science, and CENTRAL. Combinations of keywords and controlled vocabulary terms were utilized in order to cast a broad net. Relevant clinical, biomechanical, anatomic and imaging studies were reviewed along with recent review articles, and case series. Results: Forty-three articles from our initial literature search were found to be relevant for this review. The majority of these articles were either review articles, clinical studies, anatomic or imaging studies or biomechanical studies. Conclusions: Current evidence suggests that OAT may lead to better and more consistent outcomes than previously described methods for treating large OCD lesions of the capitellum.

Osteochondritis dissecans of the elbow

Capitellar osteochondritis dissecans (OCD) can be a significant problem in adolescent overhead athletes. The cause is likely multifactorial secondary to repetitive stresses, biomechanical mismatch, and a tenuous vascular supply of the capitellum. Recent literature reveals that the prevalence is likely higher than previously thought. This, in conjunction with increased levels of athletic competition in children at younger ages, has fed the recent interest in this topic. The literature continues to show that non-operative treatment is still successful for stable lesions. Unstable lesions, therefore, have been the focus of the new literature regarding operative management and outcomes. The aim of this paper is to provide a summary of current literature and an up-to-date approach to the diagnosis, evaluation, and treatment of osteochondritis dissecans of the capitellum.

Osteochondral Autograft Transplantation Surgery for Metacarpal Head Defects

Post-traumatic osteonecrosis of the metacarpal head is a challenging problem, particularly in younger patients in whom arthroplasty may not be a durable option. Although several osteochondral reconstructive options have been proposed, some are associated with considerable donor site morbidity and/or require the use of internal fixation. We present an application of osteochondral autograft transplantation surgery as a treatment option for focal metacarpal head lesions. An osteochondral plug from the non-weight-bearing articular surface of the knee is transferred and press-fit to resurface a focal metacarpal head defect. The technical pearls and pitfalls are reviewed, and an illustrative case is presented.

Evaluation of Knee Donor and Elbow Recipient Sites for Osteochondral Autologous Transplantation Surgery in Capitellar Osteochondritis Dissecans

BACKGROUND

Osteochondral autologous transplantation surgery (OATS) has been advocated for treatment of osteochondritis dissecans (OCD) of the capitellum in adolescents. However, little information is available regarding the optimal knee harvest site to match the contour and cartilage thickness of the recipient elbow lesion.

PURPOSE

To characterize the capitellar anatomic structure in adolescents with and without OCD and to compare these measurements to normal adolescent knees to identify the optimal site for osteochondral graft harvest.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-one patients with OCD were analyzed. Twenty-two patients with normal elbows and 25 age-, weight-, and height-matched patients with normal knees were also identified. Cartilage radii of curvatures (ROCs) in the sagittal and coronal-axial planes were measured on magnetic resonance imaging (MRI) of normal capitella and 5 sites (posterior lateral femoral condyle, medial and lateral middle trochlear ridges, and medial and lateral inferior trochlear ridges) in normal knees. Differences in ROC between the knee donor and capitellar recipient sites were calculated based on a 10-mm osteochondral plug diameter.

RESULTS

Overall, the mean apex differences between graft and recipient sites ranged from 0.4 to 0.9 mm, and mean edge differences ranged from 0.5 to 1.4 mm in the coronal-axial dimension. Of all knee sites tested, the posterior lateral femoral condyle had average ROCs (19.1 mm sagittal; 14.1 mm axial) most like the capitellum (10.6 mm sagittal, 12.6 mm coronal-axial), resulting in minimal apex and edge differences (apex difference = -0.6 mm; coronal-axial side difference = -0.5 mm; no sagittal side difference). Of the anterior nonweightbearing sites, the inferior medial trochlear ridge (28.3 mm sagittal ROC; 13.2 mm coronal-axial ROC) demonstrated the lowest apex and side differences when compared with the capitellum (apex difference = -0.8 mm; coronal-axial side difference = -0.8 mm; no sagittal side difference). The frequently used middle lateral trochlear ridge (28.8 mm sagittal; 8.7 mm coronal-axial ROCs) had the largest side difference (apex distance = -0.8 mm; coronal-axial side difference = -1.4 mm; no sagittal side difference).

CONCLUSION/CLINICAL RELEVANCE

In cases where a large single-plug OATS is considered, a 10-mm plug from the anterior nonweightbearing aspect of the distal femur is calculated to result in ≤1 mm of articular incongruity at the recipient capitellum. The inferior medial trochlear ridge should be considered as a donor site for OATS procedures for OCD given its accessibility and favorable geometry.