Histological analysis of the tibial anterior cruciate ligament insertion.

PURPOSE: This study was performed to investigate the morphology of the tibial anterior cruciate ligament (ACL) by histological assessment. METHODS: The native (undissected) tibial ACL insertion of six fresh-frozen cadaveric knees was cut into four sagittal sections parallel to the long axis of the medial tibial spine. For histological evaluation, the slices were stained with haematoxylin and eosin, Safranin O and Russell-Movat pentachrome. All slices were digitalized and analysed at a magnification of 20×. RESULTS: The anterior tibial ACL insertion was bordered by a bony anterior ridge. The most medial ACL fibres inserted from the medial tibial spine and were adjacent to the articular cartilage of the medial tibial plateau. Parts of the bony insertions of the anterior and posterior horns of the lateral meniscus were in close contact with the lateral part of the tibial ACL insertion. A small fat pad was located just posterior to the functional ACL fibres. The anterior-posterior length of the medial ACL insertion was an average of 10.8 ± 1.1 mm compared with the lateral, which was only 6.2 ± 1.1 mm (p < 0.001). There were no central or posterolateral inserting ACL fibres. CONCLUSIONS: The shape of the bony tibial ACL insertion was 'duck-foot-like'. In contrast to previous findings, the functional mid-substance fibres arose from the most posterior part of the 'duck-foot' in a flat and 'c-shaped' way. The most anterior part of the tibial ACL insertion was bordered by a bony anterior ridge and the most medial by the medial tibial spine. No posterolateral fibres nor ACL bundles have been found histologically. This histological investigation may improve our understanding of the tibial ACL insertion and may provide important information for anatomical ACL reconstruction.

Unicompartmental knee arthroplasty in patients with full versus partial thickness cartilage loss (PTCL): equal in clinical outcome but with higher reoperation rate for patients with PTCL.

PURPOSE: While the classical indications and contraindications for unicondylar knee arthroplasty (UKA) are widely accepted there is not yet consensus if patients with partial thickness cartilage loss (PTCL) are equally suited for treatment with UKA. The aim of our study was to determine if patients with partial thickness cartilage loss do equally well after treatment with UKA. METHODS: The study retrospectively analyzed the clinical results as well as the survival rates of 64 patients treated with UKA with the medial Oxford knee system. 32 patients had shown PTCL on preoperative radiographs, while the matched control group presented with full thickness cartilage loss (FTCL) medially. Outcome parameters were the Oxford Knee Score (OKS), the American Knee Society Score (AKS), and radiographic analysis. RESULTS: Postoperative improvement in OKS was 16 (SD 9.0) for patients with PTCL and 17 (SD 8.1) for patients with FTCL. There were no significant differences in the clinical scores between the two groups. Five Patients with PTCL had reoperation whereas there were only two in the bone on bone group. Cumulative survival at 5 years for all revisions was 84 % (95 % CI 72-92 %) for the PTCL group and 97 % (95 % CI 92-100 %) for the FTCL group. This difference was not yet significant (log rank: p = 0.095). CONCLUSIONS: Patients with PTCL are not equally suited for treatment with UKA like patients with bone on bone. Although PTCL has equal clinical results, it was associated with higher revision rates in our series.

"We create chemistry for a sustainable future": chemistry creates sustainable solutions for a growing world population.

On April 6, 1865, Friedrich Engelhorn founded the company "Badische Anilin- & Sodafabrik" in Mannheim, Germany. This Essay, commemorating the 150th anniversary of BASF, introduces several outstanding examples of innovation from the history of BASF and highlights how chemical and technical competencies developed in the past still play an essential role in current projects.

Flat midsubstance of the anterior cruciate ligament with tibial "C"-shaped insertion site.

PURPOSE: This anatomical cadaver study was performed to investigate the flat appearance of the midsubstance shape of the anterior cruciate ligament (ACL) and its tibial "C"-shaped insertion site. METHODS: The ACL midsubstance and the tibial ACL insertion were dissected in 20 cadaveric knees (n = 6 fresh frozen and n = 14 paraffined). Magnifying spectacles were used for all dissections. Morphometric measurements were performed using callipers and on digital photographs. RESULTS: In all specimens, the midsubstance of the ACL was flat with a mean width of 9.9 mm, thickness of 3.9 mm and cross-sectional area of 38.7 mm(2). The "direct" "C"-shaped tibial insertion runs from along the medial tibial spine to the anterior aspect of the lateral meniscus. The mean width (length) of the "C" was 12.6 mm, its thickness 3.3 mm and area 31.4 mm(2). The centre of the "C" was the bony insertion of the anterior root of the lateral meniscus overlayed by fat and crossed by the ACL. No posterolateral (PL) inserting ACL fibres were found. Together with the larger "indirect" part (area 79.6 mm(2)), the "direct" one formed a "duck-foot"-shaped footprint. CONCLUSION: The tibial ACL midsubstance and tibial "C"-shaped insertion are flat and are resembling a "ribbon". The centre of the "C" is the bony insertion of the anterior root of the lateral meniscus. There are no central or PL inserting ACL fibres. Anatomical ACL reconstruction may therefore require a flat graft and a "C"-shaped tibial footprint reconstruction with an anteromedial bone tunnel for single bundle and an additional posteromedial bone tunnel for double bundle.

Restoration of the tibial ACL footprint area and geometry using the Modified Insertion Site Table.

PURPOSE: This article is based on the concept of complete footprint restoration. It introduces a "Modified Insertion Site Table" for individual size-matched single- (SB) and double-bundle (DB) ACL reconstruction, which gives surgical guidelines for graft diameters and drill angles according to the restored tibial insertion site area and geometry. METHODS: Potential graft diameters and drill angles were matched for all individual tibial insertion site lengths between 8 and 21 mm. A "Modified Insertion Site Table" was calculated to achieve a maximum of area restoration of the tibial ACL footprint for each of these insertion site lengths. The geometry of the restored footprint was considered. RESULTS: A wide ACL footprint up to a 16-mm-long insertion site might be best restored with a SB-, a narrow one with a DB-ACL reconstruction. In a 17-mm-long insertion site, SB- and DB-ACL reconstructions restore a similar amount of footprint area, so geometry considerations of the footprint may decide which surgical technique may be favourized. SB can restore a maximum length of 13.1 mm and DB up to 21 mm. The width of the restored area depends on the drill bit diameter(s) and is larger for SB in most cases. In larger footprints, DB can replicate up to 63% more area and 37% more length than SB-ACL reconstruction. CONCLUSIONS: Anatomical footprint restoration requires assessment of the length, width, and the orientation of the tibial ACL insertion site. Both SB- and DB-ACL reconstruction may achieve a wide range of area and geometric restoration of the individual ACL footprint. While SB-ACL reconstruction may be best used for wide insertion sites with up to 16 mm in length, DB-ACL reconstruction has the potential to restore narrow and larger footprints up to 21 mm in length. The "Modified Insertion Site Table" resumes the concept for orientation during surgery