Yomei Tachibana

Repair Integrity Evaluated by Second-Look Arthroscopy After Arthroscopic Meniscal Repair With the FasT-Fix During Anterior Cruciate Ligament Reconstruction

Background Although several devices for meniscal repairs have become available, a successful outcome is ultimately due to a healed meniscus on the clinical findings. The authors assessed the repair integrity after meniscal repair with the FasT-Fix device using second-look arthroscopy. Hypothesis Meniscal repair with the FasT-Fix will lead to arthroscopically evident healing, but some menisci will show incomplete healing even in clinically successful cases and have newly formed injuries on the meniscal substance resulting from the path of the implant. Study Design Case series; Level of evidence, 4. Methods Sixty-five consecutive patients were studied, in whom 84 menisci were subjected to all-inside meniscal repair with the FasT-Fix device in conjunction with anterior cruciate ligament reconstruction. Repair was only performed on longitudinal or double longitudinal tears within the red-red or red-white zone. The repaired menisci were evaluated by second-look arthroscopy at the time of staged hardware removal after anterior cruciate ligament reconstruction. Results Sixty-two meniscal tears in 46 patients were available for this study. Eight patients were found to be symptomatic and considered to be clinical failures. The clinical success rate was 83%. At second-look arthroscopy, 46 tears (74%) were healed, 9 (15%) were healed incompletely, and 7 (11%) had failed. In the failed menisci,1 had meniscal symptoms, while the other 6 were asymptomatic. In the 9 menisci with incomplete healing, 3 were associated with nonspecific knee pain but none showed meniscal symptoms. Newly formed injuries, which occurred in an area different from the original repair site, were confirmed on the surface of 19 menisci (35%) among the healed and incompletely healed menisci. Thirty menisci (48%) displayed successful and complete healing of the original tear site without newly formed tears. Conclusion Meniscal repair with the FasT-Fix in conjunction with anterior cruciate ligament reconstruction resulted in complete healing in 74% of cases. Eighty-three percent of menisci were symptom-free regardless of meniscal integrity. Even when the menisci repaired are asymptomatic and considered to be a clinical success, however, there may be newly formed injuries.

Discoid medial meniscus.

A discoid medial meniscus is an extremely rare anomaly. We present 4 cases of symptomatic discoid medial meniscus. Furthermore, magnetic resonance imaging (MRI) of the unaffected knee was obtained in 3 cases, and 1 patient had bilateral discoid medial menisci as well as a unilateral discoid lateral meniscus proven by MRI. Another patient had bilateral discoid medial menisci. In one of the other 2 cases, an MRI of the unaffected knee was not obtained. However, in the involved knees of both cases, medial and lateral menisci were discoid. The incidence of bilateral discoid medial menisci is unknown. In the past, the diagnosis of a discoid meniscus was made with an arthrogram or at arthrotomy. Therefore, whether some of the unilateral cases reported in the literature might have been bilateral is unknown. The reported prevalence of bilateral discoid medial menisci will probably increase, because when a discoid medial meniscus is encountered currently, an MRI is used to find knee disorders, including in the contralateral knee. Axial multiplanar gradient-recalled-echo imaging could provide images of the discoid meniscus, depicted in its entirety in one section. This would make the recognition of a discoid meniscus simple.

Biomechanical Properties of Porcine Flexor Tendon Fixation With Varying Throws and Stitch Methods

Background: The well-known suture technique configurations used for hamstring tendon autograft preparation in anterior cruciate ligament (ACL) reconstruction are the Krackow locking stitch and nonlocking stitch, such as a baseball stitch and a whipstitch. However, there are few data in the literature regarding biomechanical comparisons of suture techniques. Purpose: The purpose of this study was to determine the properties of several current techniques of tendon graft suture employed in ACL reconstruction. Study Design: Controlled laboratory study. Methods: Forty-two fresh-frozen porcine flexor digitorum tendons were used. Three stitch configurations (Krackow stitch [group K], baseball stitch [group B], and whipstitch [group W]) were assessed with varying suture throws (6 throws, group×6; 10 throws, group×10) using No. 5 Ethibond sutures. Each group was tested at 1500 loading cycles between 50 and 200 N. After loading cycles, the surviving tendons underwent a load-to-failure test. Results: During the loading cycles, 3 of 7 specimens in group B×6 and all specimens in group W×6 failed by suture pullout. Four of 7 specimens in group B×10 and all specimens in group W×10 showed partial tearing of the tendon. Elongation of group B×10 and group W×10 showed significantly greater elongation than other groups (P < .05). Maximum loads at failure showed significant differences between group K and the other groups (K×6, 436 ± 52 N; K×10, 419 ± 34 N; P < .05). Most specimens failed by rupture of the suture thread in group K. Pullout of the suture from the tendon was observed most in groups B and W. Conclusion: The Krackow stitch was superior to other stitch methods. There was, however, no significant effect of the number of throws on the holding strength. Clinical Relevance: The Krackow stitch could prevent suture slippage by a locking mechanism. The whipstitch is not suitable for clinical application even with an increased number of throws.

Fixation strength of the interference screw in the femoral tunnel: The effect of screw divergence on the coronal plane

Clinical studies to examine the effect of screw divergence have not been applied to the fixation of hamstring grafts. A few previous reports have addressed the correlations between the loss of pullout strength and divergence on hamstring tendon fixation in biomechanical tests. The purpose of this study was to examine the effect of interference screw divergence on the coronal plane when digital flexor tendons were fixed with an interference screw. Twenty fresh porcine hindlimb specimens were chosen. The grafts were fixed using titanium soft tissue interference screws. The hindlimbs were divided into two groups according to the insertion method of the screw. The screw was placed along the graft parallel to the long axis of the femoral tunnel in 10 specimens (parallel placement group), and the others were placed laterally at a 15° divergent angle from the bone tunnel on the coronal plane (divergence group). The cyclic-loading test was loaded for 1500cycles. Five specimens failed because of a pull-out of the tendon in divergence group. The number of specimens that failed before the completion of cycles in the divergence group was significantly greater than that in the parallel placement group. Although the residual displacement after 1500cycles for the divergence group was greater than that for the parallel placement group, no statistically significant difference was found between the groups. This study suggests that the screw placed laterally at a 15° divergent angle on the coronal plane decreases the fixation strength of the digital flexor tendons fixed with an interference screw.

Dexamethasone inhibits bone resorption by indirectly inducing apoptosis of the bone-resorbing osteoclasts via the action of osteoblastic cells

Although glucocorticoids (GCs) are physiologically essentialfor bone metabolism, it is generally accepted that high dosesof GCs cause bone loss through a combination of decreased boneformation and increased bone resorption. However, the actionof GCs on mature osteoclasts remains contradictory. In thisstudy, we have examined the effect of GCs on osteoclasticbone-resorbing activity and osteoclast apoptosis, by using twodifferent cell types, rabbit unfractionated bone cells andhighly enriched mature osteoclasts (>95% of purity).Dexamethasone (Dex, 10-10–10-7 M) inhibited resorption pit formation on a dentine slice by the unfractionated bone cells in a dose- and time-dependent manner.However, Dex had no effect on the bone-resorbing activity of the isolated mature osteoclasts. When the isolated osteoclastswere co-cultured with rabbit osteoblastic cells, the osteoclastic bone resorption decreased in response to Dex,dependent on the number of osteoblastic cells. Like the effecton the bone resorption, Dex induced osteoclast apoptosis in cultures of the unfractionated bone cells, whereas it did not promote the apoptosis of the isolated osteoclasts. An inhibitorof caspases, Z-Asp-CH2-DCB attenuated both the inhibitory effecton osteoclastic bone resorption and the stimulatory effect onthe osteoclast apoptosis. In addition, the osteoblastic cellswere required for the osteoclast apoptosis induced by Dex. These findings indicate that the main target cells of GCs arenon-osteoclastic cells such as osteoblasts and that GCsindirectly inhibit bone resorption by inducing apoptosis ofthe mature osteoclasts through the action of non-osteoclasticcells. This study expands our knowledge about the multifunctional roles of GCs in bone metabolism.