Peter C. Cannamela

The Incidence of Surgery in Osteochondritis Dissecans in Children and Adolescents.

Background: The frequency of osteochondritis dissecans (OCD), a disorder of the subchondral bone and articular cartilage, is not well described. Purpose: To assess the frequency of pediatric OCD lesions that progress to surgery based on sex, joint involvement, and age. Study Design: Descriptive epidemiology study. Methods: A retrospective chart review (2007-2011) was performed on OCD. Inclusion criteria included OCD of any joint and patients aged 2 to 19 years. Exclusion criteria included traumatic osteochondral fractures or coexistence of non-OCD intra-articular lesions. Differences in progression toward surgery were compared between age groups, sex, and joint location. Logistical regression analysis was performed by sex, age, and ethnicity. Results: Overall, 317 patients with a total of 334 OCD lesions were found. The majority of lesions (61.7%) were in the knee, with ankle, elbow, shoulder, and foot lesions representing 25.4%, 12.0%, 0.6%, and 0.3% of all lesions, respectively. The majority of joints needing surgery were in the knee (58.5%), with ankle and elbow lesions representing 22.9% and 18.6% of surgeries performed, respectively. The percentage of all OCD lesions progressing to surgery was 35.3%; surgical progression for knee, ankle, and elbow joints was 33.5%, 31.8%, and 55.0%, respectively. Logistic regression analysis found no statistically significant different risk of progressing to surgery for OCD of the knee, elbow, and ankle between sexes. Patients aged 12 to 19 years had a 7.4-times greater risk of progression to surgery for knee OCD lesions than 6- to 11-year-olds. Patients aged 12 to 19 years were 8.2 times more likely to progress to surgery for all OCD lesions than patients aged 6 to 11 years. Progression to surgery of ankle OCD did not significantly differ based on location. Three of 4 trochlear lesions progressed to surgery, along with 1 of 1 tibial, 1 of 3 patellar, 40.3% of lateral femoral condylar, and 28.2% of medial femoral condylar lesions. Conclusion: In this large cohort study of pediatric OCD patients, 35% progressed to surgery. Progression to surgery did not differ significantly between sexes with OCD of any joint. Progression to surgery for OCD of the knee, elbow, and ankle strongly correlated with patient age at the time of diagnosis. Clinical Relevance: The knowledge of likelihood of progression to surgery of OCD by location, sex, and age is useful in counseling patients and in planning treatment. This study confirms a worse prognosis in the nonoperative treatment of older patients with OCD.

The Relationship of the Femoral Physis and the Medial Patellofemoral Ligament in Children A Cadaveric Study

Background: Young athletes sustain patellar dislocations in a variety of sports. The medial patellofemoral ligament (MPFL) is a critical structure that functions as an anatomic checkrein to help prevent lateral patellar dislocation. Reconstruction of this ligament is challenging in patients with open physes because of concerns about iatrogenic damage to the femoral physis. Purpose: To evaluate the relationship of the distal femoral physis and the MPFL. Study Design: Descriptive laboratory study. Methods: In 15 cadaveric, pediatric knees (age, 7-11 years), markers were placed at the proximal/distal limits of the MPFL femoral attachment and were evaluated with computed tomography. The distance from the MPFL attachment midpoint to the most medial aspect of the distal femoral physis was measured. Results: The mean femoral width of the MPFL was 8.1 mm (range, 4.3-13.8 mm). The femoral MPFL midpoint was distal to the femoral physis in 11 specimens and proximal to the physis in 4 specimens. The most proximal portion of the MPFL femoral attachment extended above the medial physis in 7, was at the physis in 5, and was below the physis in 3 specimens. One specimen had the entire MPFL femoral attachment above the physis. For knees with the MPFL midpoint above the medial physis, the distance between the center of the MPFL and physis was 3.3 mm (range, 0.3-7.1 mm). For knees with the MPFL below the medial physis, the distance between the center of the MPFL and physis was −6.8 mm (range, −0.7 to −22.0 mm). Conclusion: The relationship of the femoral attachment of the MPFL and the medial femoral physis shows some anatomic variation. In all cases, the MPFL is close to the medial femoral physis, but the midpoint of the MPFL is at, slightly above, or slightly below the physis. Clinical Relevance: The relationship of the MPFL femoral attachment footprint to the femoral physis in the skeletally immature patient is not well understood, and access to pediatric cadaveric tissue is very limited. This small series demonstrates that there is considerable variation in the relationship between the MPFL and distal femoral physis. This anatomic information may guide MPFL reconstruction technique in young patients and reduce the risk of iatrogenic physeal arrest on the femur.

Anterolateral Ligament of the Knee Shows Variable Anatomy in Pediatric Specimens

BackgroundAnterior cruciate ligament (ACL) reconstruction failure rates are highest in youth athletes. The role of the anterolateral ligament in rotational knee stability is of increasing interest, and several centers are exploring combined ACL and anterolateral ligament reconstruction for these young patients. Literature on the anterolateral ligament of the knee is sparse in regard to the pediatric population. A single study on specimens younger than age 5 years demonstrated the presence of the anterolateral ligament in only one of eight specimens; therefore, much about the prevalence and anatomy of the anterolateral ligament in pediatric specimens remains unknown.Questions/purposesWe sought to (1) investigate the presence or absence of the anterolateral ligament in prepubescent anatomic specimens; (2) describe the anatomic relationship of the anterolateral ligament to the lateral collateral ligament; and (3) describe the anatomic relationship between the anterolateral ligament and the physis.MethodsFourteen skeletally immature knee specimens (median age, 8 years; range, 7–11 years) were dissected (12 male, two female specimens). The posterolateral structures were identified in all specimens, including the lateral collateral ligament and popliteus tendon. The presence or absence of the anterolateral ligament was documented in each specimen, along with origin, insertion, and dimensions, when applicable. The relationship of the anterolateral ligament origin to the lateral collateral ligament origin was recorded.ResultsThe anterolateral ligament was identified in nine of 14 specimens. The tibial attachment point was consistently located in the same region on the proximal tibia, between the fibular head and Gerdy’s tubercle; however, the femoral origin of the anterolateral ligament showed considerable variation with respect to the lateral collateral ligament origin. The median femoral origin of the anterolateral ligament was 10 mm (first interquartile 6 mm, third interquartile 13) distal to the distal femoral physis, whereas its median insertion was 9 mm (first interquartile 5 mm, third interquartile 11 mm) proximal to the proximal tibial physis.ConclusionsThe frequency of the anterolateral ligament in pediatric specimens we observed was much lower than other studies on adult specimens; future studies might further investigate the prevalence, development, and functional role of the anterolateral ligament of the knee.Clinical RelevanceThis study expands our understanding of the anterolateral ligament and provides important anatomic information to surgeons considering anterolateral ligament reconstruction concomitantly with primary or revision ACL reconstruction in pediatric athletes.

Variation in the Medial Patellofemoral Ligament Origin in the Skeletally Immature Knee: An Anatomic Study:

Background: The medial patellofemoral ligament (MPFL) is frequently reconstructed to treat recurrent patellar instability. The femoral origin of the MPFL is well described in adults but not in the skeletally immature knee. Purpose: To identify a radiographic landmark for the femoral MPFL attachment in the skeletally immature knee and study its relationship to the distal femoral physis. Study Design: Descriptive laboratory study. Methods: Thirty-six cadaveric specimens between 2 and 11 years old were dissected and examined (29 male and 7 female). Metallic markers were placed at the proximal and distal borders of the MPFL femoral origin footprint. Computed tomography scans with 0.625-mm slices in the axial, coronal, and sagittal planes were used to measure the maximum ossified height and ossified depth. The measurements were used to describe the position of the midpoint MPFL attachment with respect to the posterior-anterior and distal-proximal dimensions of the femoral condyle on the sagittal view and to describe the distance from the physis to the femoral origin of the MPFL. Results: In 23 of 36 specimens, the femoral origin of the MPFL was distal to the physis. Thirteen of the 36 specimens had an MPFL origin at or proximal to the physis, with a more proximal MPFL origin consistently seen in older specimens. The distance of the MPFL origin to the physis ranged from 15.1 mm distal to the physis to 8.3 mm proximal to the physis. The mean midpoint of the MPFL femoral origin was located 3.0 ± 5.5 mm distal to the physis for all specimens. For specimens aged <7 years, the mean MPFL origin was 4.7 mm distal to the physis, and for specimens aged ≥7 years, the mean MPFL origin was 0.8 mm proximal to the femoral physis. The MPFL origin was more proximal and anterior for those aged ≥7 years and more distal and posterior for those aged <7 years. Conclusion: Surgical reconstruction of the MPFL is a common treatment to restore patellar stability. There appears to be significant variability in the origin of the MPFL in skeletally immature specimens. This study demonstrated that the MPFL origin was more proximal and anterior with respect to the physis in the older age group. The MPFL origin footprint may be customized for different age groups. Clinical Relevance: This information shows anatomic variation of the MPFL origin with age, with older specimens having a footprint that was more proximal and anterior than younger specimens. Customization of the surgical technique might be considered based on patient age.

Biomechanical Comparison of Epiphyseal Anterior Cruciate Ligament Fixation Using a Cortical Button Construct Versus an Interference Screw and Sheath Construct in Skeletally Immature Cadaveric Specimens

Background: Anterior cruciate ligament (ACL) ruptures have become increasingly common in pediatric and adolescent athletes. While multiple methods exist, all-epiphyseal ACL reconstruction is a popular technique in the skeletally immature patient. Given the high rate of reruptures in this population and the increasing number of commercially available fixation devices, biomechanical testing is crucial to understand the performance of these devices in pediatric epiphyseal bone. To our knowledge, there has not been a biomechanical analysis of ACL fixation devices in skeletally immature bone. Purpose: To compare cortically based button fixation with interference screw and sheath fixation in skeletally immature femoral epiphyseal cadaveric bone. Our hypothesis was that there would be no difference in peak load to failure, stiffness, or cyclic displacement between these 2 fixation constructs. Study Design: Controlled laboratory study. Methods: Fresh-frozen matched-pair knees from 3 pediatric cadaveric specimens were obtained. A synthetic graft was fixed in an all-epiphyseal femoral tunnel. Both the lateral and medial condyles were utilized to increase the sample size. Specimens were randomized and assigned to receive either an interference screw and sheath construct designed for pediatric patients or an adjustable loop cortical button. Biomechanical testing was performed to obtain ultimate load to failure, stiffness, total displacement after 500 cycles, and the failure mode for each condyle. Results: Each medial and lateral condyle in 3 pairs of skeletally immature cadaveric knees (ages 7, 9, and 11 years) was utilized for testing. One specimen was excluded after it failed by having a transphyseal fracture. The median peak load to failure was 769.80 N (interquartile range [IQR], 628.50-930.41 N) for the screw and sheath group and 862.80 N (IQR, 692.34-872.65 N) for the button group (P = .893). The median displacement after 500 cycles for the screw and sheath group was 0.65 mm (IQR, 0.47-1.03 mm) and 1.13 mm (IQR, 0.96-1.25 mm) for the button group (P = .08). The median stiffness of the screw and sheath group was significantly higher than that of the button group (31.47 N/mm [IQR, 26.40-43.00 N/mm] vs 25.22 N/mm [IQR, 21.18-27.07 N/mm], respectively) (P = .043). Conclusion: When comparing femoral fixation with a screw and sheath construct developed for pediatric patients to an adjustable loop cortical button in skeletally immature bone, our results showed that fixation did not significantly differ with respect to cyclic displacement or peak load to failure. While the screw and sheath construct was significantly stiffer, its effect on clinical outcomes is not yet known. Clinical Relevance: With regard to femoral fixation, there is no significant biomechanical difference between the use of cortically based button fixation or interference screw and sheath fixation in pediatric epiphyseal cadaveric bone.

Developmental Anatomy of the ACL and Knee

The anterior cruciate ligament (ACL) originates from the mesenchyme and becomes a distinct cruciate ligament from the posterior cruciate ligament (PCL) by week 10. The ACL is associated with two distinct bundles, anteromedial (AM) and posterolateral (PL), that originate on the lateral femoral condyle and insert on the intercondylar spine of the tibia. As the primary stabilizer of the knee, the ACL is responsible for resisting anterior translation and rotation of the tibia on the femur. Both the physis (growth plate) and tibial tuberosity lie in close proximity to the ACL. Pediatric ACL reconstruction can be challenging due to the risk of causing damage to the physis, articular cartilage, lateral collateral ligament (LCL), popliteus tendon, and meniscus. Future prospective studies are needed to determine optimal techniques for management of ACL injuries in those with open growth plates.

The distance between the hamstring grafts and the physis and apophysis of the proximal tibia - implications for pediatric ACL reconstruction and physeal arrest

Objectives To evaluate the relationship of the gracilis and semitendinosus tendon and the proximal tibial physis and apophysis regions on human paediatric knee specimens. Methods Metallic markers were placed at the proximal and distal extents of the anterior margin of the pes anserine in 24 paediatric knee specimens (ages 2 to 11 years). CT scans from each specimen were analysed using OsiriX. The distance from the proximal and distal tibial epiphysis and pes anserine insertion (proximal and distal extent) was measured in the sagittal plane. The medial–lateral distance from the centre of the apophysis to the pes anserine insertion was measured in the axial plane. Results In the sagittal plane, the anteroproximal pes anserine insertions were found to be distal to the proximal tibia physis by a mean of 21.4 mm (range 13.1–30.5 mm). In the axial plane, the mean distance from the anteroproximal extent of the pes anserine to the tibial apophysis was 6.6 mm (range 3.1–12.3 mm). No clear trend was observed based on age. Conclusions The distance from the pes anserine insertions to the physis apophyseal region of the tibia is relatively small. Dissections in this area should consider the intimate relationships of the physeal/apophyseal structures. Techniques that strip the tendons and surrounding periosteum from the insertions may damage the peripheral regions of physeal/apophyseal regions. Graft harvest from the pes anserine (gracilis and semitendinosus) should consider modifications of the surgical technique that avoid direct injury to the vulnerable physeal/apophyseal regions. Level of evidence Level IV.

Anatomic all-epiphysial tibial tunnels for anterior cruciate ligament reconstruction in skeletally immature knees may be placed without damaging the anterior meniscus root

Objectives The purpose of this study was to evaluate the spatial relationship of the anterior horns of the menisci and the tibial tunnel during all-epiphysial drilling of skeletally immature specimens and identify any iatrogenic damage or destabilisation to the meniscus and meniscal root. Methods Four skeletally immature cadaveric knee specimens (aged 9–11 years) were used to create three-dimensional models from CT images. All-epiphysial anterior cruciate ligament (ACL) tibial tunnel drilling was performed in 14 specimens (aged 7–11 years), entering the joint surface at the ACL footprint and avoided the proximal tibial physis. The anterior meniscal roots and horns were closely inspected visually and probed for stability, prior to drilling. After drilling, the meniscus and attachment points were re-evaluated for damage to the meniscus, meniscus root and probed to evaluate for destabilisation. Results All-epiphysial tunnels entered the joint at the anatomic ACL tibial footprint. Direct visual inspection of the menisci demonstrated an absence of damage to either meniscus or anterior horn regions in all specimens. Probing and traction of the medial and lateral meniscal tissue did not demonstrate evidence of instability or destabilisation of the anterior horn or meniscus root before or after drilling. All tunnels were circumferentially intact at the joint surface, with no evidence of superior tunnel perforation due to shallow tunnel angle. Conclusion In this study, tunnel placement did not produce damage to either meniscus, nor noticeably destabilise the meniscal roots. This study also demonstrated that drill holes can be placed within the ACL footprint without entering the joint on the proximal tibia surface anterior to the ACL attachment, although the ‘safe zone’ for drill hole placement is limited. All-epiphysial ACL tibial tunnels can create a large aperture at the tibial joint surface, but these tunnels can be placed at the anatomic footprint of the ACL, without causing gross anterior medial or lateral meniscus horn or root injury.

Avoiding tibia physeal injury during double-bundle posterior cruciate ligament reconstruction

Background Anatomic studies of the paediatric posterior cruciate ligament (PCL) demonstrate that the tibial attachment spans the epiphysis, physis and metaphysis. To better reproduce the anatomy of the PCL and avoid direct physeal injury, a double-bundle PCL reconstruction technique that includes both an all-epiphysial and an all-metaphyseal tibial tunnel has been proposed. The purpose of this study was to evaluate tibial tunnel placement in a paediatric double-bundle PCL reconstruction technique that avoids direct physeal injury using a 3-D computer model. Methods Ten skeletally immature cadaveric knee specimens (ages 5–11) were used to create 3-D model reconstructions from CT scans. All-metaphyseal and all-epiphysial tibial tunnels were simulated with the goal of maintaining adequate spacing (≥2 mm) between the tibial physis and tunnels to avoid injury. The all-metaphyseal tunnel, simulated at sizes of 5, 6 and 7 mm, entered anteriorly, below the tibial tubercle (apophysis) and exited posteriorly in the metaphyseal PCL footprint, distal to the proximal tibial physis. Four-millimetre all-epiphysial proximal tibial tunnels were simulated to enter the epiphysis anteromedially and exit posteriorly at the central epiphysial region of the PCL footprint, proximal to the physis. The distance was measured from the all-metaphyseal tunnels to the physis posteriorly and from the all-epiphysial tunnels to the physis, both anteriorly and posteriorly. Results In all specimens, the 4 mm all-epiphysial tunnel and the 5, 6 and 7 mm all-metaphyseal tunnels maintained adequate spacing, ≥2 mm from the physis. In the specimens aged 5–7 years, the 5, 6 and 7 mm all-metaphyseal tunnels measured a mean distance of 3.5, 2.8 and 2.5 mm from the physis, respectively. In the specimens aged 8–11 years, the 5, 6 and 7 mm all-metaphyseal tunnels measured a mean distance of 3.4, 2.9 and 2.6 mm from the physis. In the specimens aged 5–7 years, the all-epiphysial tunnel measured a mean of 2.1 mm to the physis anteriorly and a mean of 2.8 mm posteriorly. In the specimens aged 8–11 years, the all-epiphysial tunnel measured a mean of 2.2 mm to the physis anteriorly and 2.4 mm posteriorly. Conclusion These computer-aided 3-D models of paediatric knees illustrate that 5, 6 and 7 mm all-metaphyseal tunnels as well as 4 mm all-epiphysial tunnels can be placed without direct injury to the proximal tibial physis. The margin of error for direct physeal injury is small, especially for the all-epiphysial tunnel. Further, the all-epiphysial tunnel, while reproducing the anatomy of the PCL epiphysial attachment, may also produce a more extreme ‘killer turn’ of the graft. Modifications to the all-epiphysial tunnel may be considered to reduce the impact of the high ‘killer turn’ angle on the tibia. Level of evidence IV.

Ossification Variants in the Femoral Condyles and Trochleae are Caused by Lesions of Osteochondrosis Manifesta in Children

Objectives: Over the last 50 years, the genesis of OCD lesions has been thought secondary to a primary bone necrosis origin. This theory has been challenged recently, as histological studies performed on specimens obtained from asymptomatic mammals, have revealed that ischemic necrosis of epiphyseal cartilage (rather than bone) is the precursor lesion of osteochondrosis dissecans (OCD) in several animal species. The earliest lesion identified histologically is osteochondrosis (OC) latens, in which the area of necrosis is confined to epiphyseal cartilage. As the ossification front advances, the area of necrosis causes a delay/failure in endochondral ossification that is visible radiographically and by CT and is termed OC manifesta. Juvenile osteochondritis dissecans (JOCD) in children has many similarities to OCD in animals; however, subclinical disease in children has not been studied due to the invasive nature of this work and the difficulty in obtaining appropriate cadaveric specimens. Lesions of OC latens are not recognized in children, and lesions resembling OC manifesta identified by CT are often considered to be normal ossification variants. Previous work by our group identified 32 suspected OC manifesta lesions in the medial and lateral femoral condyles (MFC and LFC) and the lateral trochlear ridge (LTR) in 14 cadaveric specimens from children ranging in age from 7 to 11 years. Our aim was to determine if skeletally immature human knees contained histological evidence of delayed endochondral ossification occurring secondary to ischemic necrosis of epiphyseal cartilage. Methods: Eleven sites (4 MFC, 4LFC, 3LTR) containing suspect OC manifesta lesions identified on CT from five male children (age range 7-11 years) were decalcified in 10% EDTA. Areas corresponding to the CT lesions were trimmed into 3-mm thick slabs (n=2-4 slabs/site), processed into paraffin, sectioned at 5 µm, and stained with hematoxylin and eosin. All sections (n= 30 total) were examined by four veterinary pathologists/radiologists with extensive experience in the study of OC in pigs and horses. Results: All sites examined contained at least one section containing histological evidence of one or more areas of OC manifesta Lesions were evidenced by focal failure of endochondral ossification accompanied by remnants of necrotic blood vessels, chondrocyte necrosis with matrix degeneration. Some lesions were accompanied by evidence of repair/healing response, including chondrocyte clusters, proliferating blood vessels, and fibrous connective tissue. Conclusion: Similar to other mammals, human OCD lesions appear to develop as a primary defect secondary to avascular necrosis of epiphyseal cartilage, rather than primary avascular necrosis in bone. Our findings strongly support a common pathogenesis of OCD in humans and mammals. Historically, ossification variants have been considered a developmental anomaly with a benign clinical course. Our histologic findings suggest that ‘ossification variants’ may in face be delayed presentations of a continuum of OCD lesion development that starts years earlier due to primary epiphyseal cartilage necrosis. Some of these ‘variants’ may progress to healing, but many may progress to frank ‘osteochondritis dissecans’, suggesting that these lesions that are idenfitifed on xray or with MRI sequences require close follow-up.