Anatomic and Biomechanical Properties of Flat Medial Patellofemoral Ligament Reconstruction Using an Adductor Magnus Tendon Graft: A Human Cadaveric Study

Background: In contrast to the majority of existing techniques for reconstruction of the medial patellofemoral ligament (MPFL), the technique described in this article uses the adductor magnus muscle tendon to gain a flat, broad graft, leaving its distal femoral insertion intact, and does not require drilling within or near the femoral physis. It also allows for soft tissue patellar fixation and could facilitate anatomic MPFL reconstruction in skeletally immature patients. Purpose: To evaluate the anatomic and structural properties of the native MPFL and the adductor tendon (AT), followed by biomechanical evaluation of the proposed reconstruction. Study Design: Descriptive laboratory study. Methods: The morphological and topographical features of the AT and MPFL were evaluated in 12 fresh-frozen cadaveric knees. The distance between the distal insertion of the AT on the adductor tubercle and the adductor hiatus, as well as the desired length of the graft, was measured to evaluate this graft’s application potential. Load-to-failure tests were performed to determine the biomechanical properties of the proposed reconstruction construct. The construct was placed in a uniaxial testing machine and cyclically loaded 500 times between 5 and 50 N, followed by load to failure, to measure the maximum elongation, stiffness, and maximum load. Results: The mean ± SD length of the AT was 12.6 ± 1.5 cm, and the mean distance between the insertion on the adductor tubercle and adductor hiatus was 10.8 ± 1.3 cm, exceeding the mean desired length of the graft (7.5 ± 0.5 cm) by 3.3 ± 0.7 cm. The distal insertion of the AT was slightly proximal and posterior to the insertion of the MPFL. The maximum elongation after cyclical loading was 1.9 ± 0.4 mm. Ultimately, the mean stiffness and load to failure were 26.2 ± 7.6 N/mm and 169.7 ± 19.2 N, respectively. The AT graft failed at patellar fixation in 2 of the initially tested specimens and at the femoral insertion in the remaining 10. Conclusion: The described reconstruction using the AT has potential for MPFL reconstruction. The AT graft presents a graft of significant volume, beneficial anatomic topography, and adequate tensile properties in comparison with the native MPFL following the data from previously published studies. Clinical Relevance: Given its advantageous anatomic relationship as an application that avoids femoral drilling and osseous patellar fixation, the AT may be considered a graft for MPFL reconstruction in skeletally immature patients.

PATTERNS OF ADDUCTOR HIATUS IN NIGERIANS: A CADAVERIC STUDY

Introduction: Adductor hiatus (AH), an osseo- muscular or osseo- fibrous space between adductor magnus muscle or aponeurosis and the shaft of femur has been classified into four different types. The interest in the hiatus is due to the large vascular structures that traverses the hiatus which is of concern to the surgeons. Materials and Methods: A total of 61 embalmed cadavers (102 limbs), 35 female lower limbs and 67 male lower limbs were dissected to show AH. Results: The bridging fibrous which shows the highest frequency was observed in 44 limbs. It exhibited incidence of 43.1% prevalence of AH shape on both sexes. The incidence in male was 27.5% while in female it was 15.7%. The bridging muscular type, the least occurrence shows incidence of 17.6% in both sexes; in males, 13.7% and in females, 3.9%. Oval fibrous type shows a prevalence of 20.5% in both sexes, 12.7% in males and 7.8% in females. Oval muscular type shows 18.6% incidence in both sexes. In males, 11.8% and in females, 6.9%. The distance from the apex of AH to the adductor tubercle was measured and shows a range of 5.0cm-17.0cm with a mean distance of 10.3cm. Conclusion: The result of this study showed that bridging fibrous AH type exhibited the highest prevalence depicting variation from another racial study. Therefore to adopt an appropriate surgical intervention in a situation of adductor canal outlet syndrome, the surgeon has to be aware of the population variations. KEY WORDS: Adductor hiatus, Adductor magnus, femoropopliteal compression, Nigerians.

Differential anatomy within the femoral origin of the medial patellofemoral complex: Implications or reconstruction

Objectives: The medial patellofemoral complex (MPFC) includes the medial patellofemoral ligament (MPFL) and medial quadriceps tendon femoral ligament (MQTFL). Recent reports have described reconstruction of this fan-shaped ligament to treat patellar instability using a double stranded technique to recreate both components of the complex, with a common origin on the medial femur. Much effort has been placed on accurately identifying the “point” of femoral origin during reconstruction due to the influence of femoral tunnel position on MPFC graft function, however, the MPFC origin is elongated in nature. Therefore, the purpose of this study was to describe the shape and orientation of the MPFC origin and identify the difference between the most proximal and distal margins of the elongated femoral footprint. Methods: 20 paired fresh frozen cadaveric knees were dissected. From an intraarticular approach, the MPFC was exposed and followed to its footprint on the medial femur. All other soft tissue was removed from the distal femur, and the footprint of the MPFC, the adductor tubercle and medial epicondyle were marked. Images of the medial femur were analyzed using Image J software. The length and width of the MPFC footprint was described to the nearest 0.1mm, as well as the angle of the long axis of the footprint relative to the axis of the femoral shaft (0.1 degrees). The position of the footprint’s most proximal and distal margins were identified and described in relation to the adductor tubercle and medial epicondyle. The positions for each were compared using paired t tests. Results: 17 knees from 10 cadavers (7M, 3F, mean age 73.1) were included in this study. The MPFC femoral footprint had a length of 11.7mm+/-1.8mm (Range 9.6,15.7) and a width of 1.7mm+/-0.4mm (Range, 0.9, 2.2). The long axis of the footprint was found to lie at an angle 14.6+/-16.6 degrees anterior to the axis of the femoral shaft. The most proximal fibers originated 7.4mm+/-3.8mm anterior and 1.8mm+/-4.7mm distal to the adductor tubercle, and 4.1mm+/-2.6mm posterior and 8.4mm+/-5.6mm proximal to the medial epicondyle. The most distal fibers originated 4.9mm+/-4.2mm anterior and 1.3mm+/-4.3mm and distal to the adductor tubercle, as well as 7.1mm+/-2.4mm posterior and 0.5mm+/-5.6mm distal to the medial epicondyle. Overall, the distal margin of the footprint was 10.9mm+/-1.7mm distal (p<0.001) and 2.6mm+/-3.2mm more posterior (p=0.005) than the proximal margin of the MPFC origin. Conclusions: The femoral footprint of the MPFC is ribbon shaped, with the distal margin being 10.9 mm distal and 2.6 mm posterior to the proximal margin. This differential anatomy of the femoral origin suggest that MPFL and MQTFL reconstruction may require separate placements of the femoral tunnels to anatomically recreate these fibers. Further biomechanical studies are needed to determine the optimal femoral tunnel placement in the setting of double-limbed MPFC reconstruction, as well as the long term benefit of this technique in the treatment of patellar instability.

The third osseous ambiguous tubercle-A study on Indian population

Background & Aim: Bony prominences on the medial side of the lower end of femur include the adductor tubercle and the medial epicondyle. A third osseous ambiguous tubercle or the Gastrocnemius tubercle is often noted about which there is not much mention in standard textbooks of Anatomy. This tubercle gives attachment to the medial head of gastrocnemius muscle. Its clinical relevance cannot be under estimated particularly in cases of treatment of rupture of medial head of gastrocnemius [Tennis leg] and while raising of Gastrocnemius flaps. Materials and Methods: This study was conducted in150 dry femora and in 10 dissected knee joints [Total femora 160 : 150 dry bones+ 10 cadaveric femora] gross specimens. The presence of gastrocnemius tubercle, supracondylar tubercle, the distances between gastrocnemius tubercle and adductor tubercle, medial epicondyle and condylar margin were measured. Results: The incidence of gastrocnemius tubercle was 55% and was predominantly noted on the right side [63%]. The average distance between the gastrocnemius tubercle and the adductor tubercle was 6 mm, and the average distance between the gastrocnemius tubercle and medial epicondyle was 15 mm. The incidence ofsupracondylartubercle was 71% and in 95% of the bones it was noted above the medial condylar margin. Conclusion: The awareness of the presence of gastrocnemius tubercle and supracondylar bony prominences in the medial side of lower end of femur will be of much use to the Orthopaedic surgeons and Plastic surgeons

Radiographic Morphology and Method for Localization of the Adductor Tubercle on Anterior–Posterior Knee Radiographs

The adductor tubercle (AT) is a landmark for joint line identification in knee arthroplasty. Up to now, there has not been a dedicated study to define its morphology on an anterior–posterior (AP) radiograph. As a result, radiographic localization of the AT has been inconsistent and confusing. Ten bone specimens, each with the AT labeled with a metal marker, were radiographed to demonstrate the AT appearance on AP radiographs. Based on this knowledge, a method to locate the AT was developed. A total of 200 clinical radiographs were examined to further confirm the observed radiographic morphology with emphasis on the visibility of the AT and its association with the rotational status of the knee on radiographs. One hundred of them were used to test the reliability of this method of AT identification. Of the 200 ATs, 153 (76%) were clearly visible on radiographs as a faint pyramid-shaped shadow protruding outward from the inflexion point of the concave–convex silhouette over the femoral shaft-condylar junction, allowing direct identification. For invisible ATs (24%), this inflexion point was found to be a useful surrogate landmark for their identification. Locating the AT using this technique showed a good intra- and interobserver reliabilities. The proposed method may be valuable for the consistent use of this landmark in joint line identification on radiographs.