Goro Tajima

Morphology of the tibial insertion of the posterior cruciate ligament.

BACKGROUND It has been demonstrated that double-bundle reconstruction of the posterior cruciate ligament restores knee kinematics better than does single-bundle reconstruction. The objective of this study was to identify the tibial insertion site of the posterior cruciate ligament and the related osseous landmarks to help guide surgeons in the performance of an anatomical double-bundle reconstruction of the posterior cruciate ligament. METHODS Twenty-one unpaired human cadaver knees were evaluated. The geometric data and surface features of the tibial insertion site of the posterior cruciate ligament and its bundles were studied with macroscopic observation and with three-dimensional laser photography. RESULTS The mean surface areas (and standard deviations) of the anterolateral and posteromedial insertion sites were 93.1+/-16.6 mm2 and 150.8+/-31.0 mm2, respectively, and the distance between their centers was 8.2+/-1.3 mm. The mean length and width of the anterolateral insertion site were 7.8+/-1.5 mm and 9.2+/-1.6 mm, and the mean length and width of the posteromedial insertion site were 9.4+/-1.4 mm and 15.0+/-2.7 mm. The average distances from the anterior and medial margins of the tibial plane to the center of the anterolateral insertion, defined as percentage ratios of the anteroposterior and mediolateral dimensions, were 83.4%+/-3.4% and 47.1%+/-1.9%, respectively, and the average distances from the anterior and medial margins of the tibial plane to the center of the posteromedial insertion were 95.5%+/-1.9% and 43.8%+/-2.2%. A notable change in angle, of >10 degrees, was observed between the anterolateral and posteromedial slopes in sixteen of the twenty-one knees. The average angle between the anterolateral and posteromedial slopes was 14.5 degrees+/-6.4 degrees. CONCLUSIONS The tibial insertion site of the posterior cruciate ligament and its bundles is very complex. However, the shapes and positions of the insertion sites of the two bundles are consistent in that they are located in different planes on the posterior intercondylar fossa. We noted a consistent change in slope between the tibial insertion sites of the anterolateral and posteromedial bundles.

PCL to graft impingement pressure after anatomical or non-anatomical single-bundle ACL reconstruction

BackgroundAnterior cruciate ligament (ACL) graft impingement against the posterior cruciate ligament (PCL) has been postulated, but not thoroughly investigated.PurposeTo evaluate PCL impingement pressure and biomechanical stability with different tibial and femoral tunnel positions in ACL reconstruction.MethodsIn 15 porcine knees, the impingement pressure between ACL and PCL was measured using pressure sensitive film before and after ACL single-bundle reconstruction. ACL reconstructions were performed in each knee with three different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM–AM), (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL–High-AM) and (3) tibial AM tunnel to femoral High-AM tunnel (AM–High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system.ResultsThere was no significant difference of the impingement pressure between AM and AM, PL–High-AM reconstructed groups and intact ACL. Only AM–High-AM ACL reconstruction group showed significantly higher impingement pressure compared with intact ACL. With regard to ATT, AM–AM group had significantly higher stiffness than PL–High-AM group.ConclusionAnatomical ACL reconstruction does not cause PCL impingement and it has biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in porcine knee. For the clinical relevance, in the anatomical ACL reconstruction, no ACL–PCL impingement is found.

Upregulation of CD44 mRNA expression by interleukin-1β in cultured rabbit articular chondrocytes

We investigated the effects of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) on CD44 mRNA expression in cultured rabbit articular chondrocytes. High-density-suspension-cultured chondrocytes were exposed to IL-1β (0.1, 1, or 10 ng/ml) or TNF-α (0.1, 1, or 10 ng/ml). Quantitative detection of specific mRNA for CD44 was carried out by reverse transcription, polymerase chain reaction (RT-PCR). Furthermore, to determine the degradation of cartilage matrix by IL-1β and TNF-α, the concentrations of chondroitin 4-sulfate (C4S) and chondroitin 6-sulfate (C6S) released to the culture medium were measured with high-performance liquid chromatography (HPLC). CD44 mRNA expression was increased significantly in chondrocytes cultured with IL-1β, but not in the chondrocytes cultured with TNF-α. The release of chondroitin sulfates (C4S+C6S) to the culture medium was also accelerated by IL-1β but was not affected by TNF-α. These results suggest that IL-1β can promote CD44 mRNA expression, together with the degradation of the cartilage matrix, and may assist in binding hyaluronic acid (HA) and CD44 in the chondrocytes.

Reinvestigation of the Morphological Characteristics of the Lateral Ulnar Collateral Ligament in Humans

To clarify the cause of posterolateral rotatory instability after damage to the lateral ulnar collateral ligament (LUCL), the morphological characteristics of the LUCL were reinvestigated and three-dimensional (3D) image of the ligament was reconstructed using 35 human elbows. The results were as follows: 1) the insertion point of the LUCL on the humerus was almost at the center of the capitellum, and its width was 2.61 ± 1.02 mm. The insertion point of the LUCL on the ulna was located from the lesser sigmoid notch to the supinator crest and had a width of 9.0 ± 2.8 mm. The proximal insertion of the LUCL on the ulna was 7.0 ± 3.0 mm, and the distal part was on the articular surface of the radial head. 2) Three-dimensional imaging of the LUCL revealed an anterior curved shape that covered the radial head. Based on these results, it was clear that both the supinator crest and the lesser sigmoid notch could be useful as osseous landmarks. We think that these anatomical results are useful for surgeons performing LUCL reconstruction.

Morphology of the Lateral Ulnar Collateral Ligament of the Elbow

Objective: The lateral ulnar collateral ligament (LUCL) is considered to be the main factor against posterolateral rotatory instability (PLRI). The aim of this study was to clarify the morphological features of the LUCL and the related osseous landmarks on 3-dimensional (3D) images. We hypothesized that the characteristic features of the LUCL and related structures can be identified, which may assist surgeons in performing LUCL reconstruction with a more anatomic perspective. Materials and Methods: Thirty-five nonpaired, formalin-fixed human cadaveric elbows were evaluated in this study. After the identification of the LUCL, the outlines of the ligament were marked by using soft stainless wires. 3D images were created, and the insertions and running route of the LUCL and related osseous landmarks were analyzed. Results: The LUCL originated from the anterior edge of the prominence at the lateral epicondyle and inserted from the lesser sigmoid notch to the supinator crest with increasing width. In the 3D images, the LUCL formed an anterior curved shape and covered the radial head like a hammock. The insertion of the LUCL at the humerus was nearly at the center of the capitellum, with a width of 2.61 ± 1.02 mm. The insertion of the LUCL at the ulna was located from the lesser sigmoid notch to the supinator crest, with a width of 9.0 ± 2.8 mm. The proximal end of the LUCL insertion at the ulna was 7.0 ± 3.0 mm distal to the articular surface of the radial head. On the horizontal plane, the LUCL was located on the radial head at 99.5° ± 10.3° to 126.1° ± 12.4°. Conclusions: The LUCL insertion at the humerus was nearly at the center of the capitellum, and the LUCL insertion at the ulna was located from the lesser sigmoid notch to the supinator crest. This study showed that both the supinator crest and lesser sigmoid notch could be useful as osseous landmarks. The LUCL was attached to the annular ligament at 8 to 9 o’clock position in the radial head, which stabilizes the radial head. On the basis of these morphological features, the LUCL might act a posterior buttress for the radial head and the ulna to prevent its subluxation, and therefore it is considered to be the principal constraint of the elbow joint against PLRI. The results of this study may assist surgeons in performing LUCL reconstruction with a more anatomic perspective.