Yuta Tachibana

Absorption of the Bone Fragment in Shoulders With Bony Bankart Lesions Caused by Recurrent Anterior Dislocations or Subluxations When Does It Occur

Background: Recently, bony defects of the glenoid in patients with traumatic anterior shoulder instability have been increasingly noticed. The bone fragment of a bony Bankart lesion is often utilized for Bankart repair, but the fragment is at times smaller than the glenoid defect. The reason for this mismatch in size is unknown. Hypothesis: The bone fragment of a bony Bankart lesion might gradually be absorbed over time. Study Design: Case series; Level of evidence, 4. Methods: A total of 163 shoulders were prospectively examined by computed tomography. In shoulders with bony Bankart lesions, glenoid defects and bone fragment absorption were assessed, and findings were compared with the time elapsed after the primary traumatic episode. When a bone fragment was not detected despite loss of the normal contour of the glenoid rim, the findings were classified as erosions if the rim appeared round and slightly compressed and classified as complete bone fragment absorption if the rim appeared straight and sharp. Results: There were no glenoid defects in 55 shoulders, erosions in 16 shoulders, and glenoid defects in 92 shoulders. The size of the glenoid defect was 0% to 10% in 15 shoulders, 10% to 20% in 44, 20% to 30% in 26, 30% to 40% in 6, and 40% to 50% in 1. The average defect size was 7.9% in shoulders scanned at <1 year, 10.7% between 1 and 2 years, and 11.3% at >2 years, indicating no relationship with time after trauma. Regarding bone fragment absorption, all 92 shoulders with glenoid defects showed absorption to some extent. The extent of absorption was <50% in 32 shoulders, >50% in 45, and 100% in 15. The average extent of absorption was 51.9% in shoulders scanned at <1 year, 65.3% between 1 and 2 years, and 70.0% at >2 years, indicating a significant relationship with time after trauma. Conclusion: Bone fragment absorption was seen in all of the shoulders with bony Bankart lesions. Most bone fragments showed severe absorption within 1 year after the primary traumatic episode. Before arthroscopic Bankart repair, not only glenoid defects but also bone fragment absorption should be assessed.

Anatomic ACL reconstruction: rectangular tunnel/bone–patellar tendon–bone or triple-bundle/semitendinosus tendon grafting

AbstractAnatomic ACL reconstruction is the reasonable approach to restore stability without loss of motion after ACL tear. To mimic the normal ACL like a ribbon, our preferred procedures is the anatomic rectangular tunnel (ART) technique with a bone-patellar tendon-bone (BTB) graft or the anatomic triple bundle (ATB) procedure with a hamstring (HS) tendon graft. It is important to create tunnel apertures inside the attachment areas to lessen the tunnel widening. To identify the crescent-shaped ACL femoral attachment area, the upper cartilage margin, the posterior cartilage margin and the resident’s ridge are used as landmarks. To delineate the C-shaped tibial insertion, medial intercondylar ridge, Parson’s knob and anterior horn of the lateral meniscus are helpful. In ART-BTB procedure which is suitable for male patients engaged in contact sports, the parallelepiped tunnels with rectangular apertures are made within the femoral and tibial attachment areas. In ATB-HS technique which is mainly applied to female athletes engaged in non-contact sports including skiing or basketball, 2 femoral and 3 tibial round tunnels are created inside the attachment areas. These techniques make it possible for the grafts to run as the native ACL without impingement to the notch or PCL. After femoral fixation with an interference screw or cortical fixation devices including Endobutton, the graft is pretensioned in situ by repetitive manual pulls at 15–20° of flexion, monitoring the graft tension with tensioners on a tensioning boot installed on the calf. Tibial fixation with pullout sutures is achieved using Double Spike Plate and a screw at the pre-determined amount of tension of 10–20N. While better outcomes with less failure rate are being obtained compared to those in the past, higher graft tear rate remains a problem. Improved preventive training may be required to avoid secondary ACL injuries.

Vibration acceleration promotes bone formation in rodent models

All living tissues and cells on Earth are subject to gravitational acceleration, but no reports have verified whether acceleration mode influences bone formation and healing. Therefore, this study was to compare the effects of two acceleration modes, vibration and constant (centrifugal) accelerations, on bone formation and healing in the trunk using BMP 2-induced ectopic bone formation (EBF) mouse model and a rib fracture healing (RFH) rat model. Additionally, we tried to verify the difference in mechanism of effect on bone formation by accelerations between these two models. Three groups (low- and high-magnitude vibration and control-VA groups) were evaluated in the vibration acceleration study, and two groups (centrifuge acceleration and control-CA groups) were used in the constant acceleration study. In each model, the intervention was applied for ten minutes per day from three days after surgery for eleven days (EBF model) or nine days (RFH model). All animals were sacrificed the day after the intervention ended. In the EBF model, ectopic bone was evaluated by macroscopic and histological observations, wet weight, radiography and microfocus computed tomography (micro-CT). In the RFH model, whole fracture-repaired ribs were excised with removal of soft tissue, and evaluated radiologically and histologically. Ectopic bones in the low-magnitude group (EBF model) had significantly greater wet weight and were significantly larger (macroscopically and radiographically) than those in the other two groups, whereas the size and wet weight of ectopic bones in the centrifuge acceleration group showed no significant difference compared those in control-CA group. All ectopic bones showed calcified trabeculae and maturated bone marrow. Micro-CT showed that bone volume (BV) in the low-magnitude group of EBF model was significantly higher than those in the other two groups (3.1±1.2mm3 v.s. 1.8±1.2mm3 in high-magnitude group and 1.3±0.9mm3 in control-VA group), but BV in the centrifuge acceleration group had no significant difference compared those in control-CA group. Union rate and BV in the low-magnitude group of RFH model were also significantly higher than those in the other groups (Union rate: 60% v.s. 0% in the high-magnitude group and 10% in the control-VA group, BV: 0.69±0.30mm3 v.s. 0.15±0.09mm3 in high-magnitude group and 0.22±0.17mm3 in control-VA group). BV/TV in the low-magnitude group of RFH model was significantly higher than that in control-VA group (59.4±14.9% v.s. 35.8±13.5%). On the other hand, radiographic union rate (10% in centrifuge acceleration group v.s. 20% in control-CA group) and micro-CT parameters in RFH model were not significantly different between two groups in the constant acceleration studies. Radiographic images of non-union rib fractures showed cartilage at the fracture site and poor new bone formation, whereas union samples showed only new bone. In conclusion, low-magnitude vibration acceleration promoted bone formation at the trunk in both BMP-induced ectopic bone formation and rib fracture healing models. However, the micro-CT parameters were not similar between two models, which suggested that there might be difference in the mechanism of effect by vibration between two models.

Postoperative Recurrence of Instability Due to New Anterior Glenoid Rim Fractures After Arthroscopic Bankart Repair

Background: Computed tomography (CT) sometimes reveals a new fracture of the anterior glenoid rim in patients with postoperative recurrence of instability after arthroscopic Bankart repair using suture anchors, but there have been few previous reports about such fractures. Hypothesis: The placement of a large number of suture anchors during arthroscopic Bankart repair might be associated with a new glenoid rim fracture. Study Design: Cohort study; Level of evidence, 3. Methods: Screw-in metal suture anchors were used until June 2011 and suture-based soft anchors from July 2011. A follow-up of at least 2 years was conducted for 128 shoulders treated using metal anchors (metal anchor group) and 129 shoulders treated using soft anchors (soft anchor group). The frequency and features of new glenoid rim fractures were investigated, and the influence of the number of suture anchors and other factors on fractures was also assessed. Results: There were 19 shoulders (14.8%) with postoperative recurrence in the metal anchor group and 23 shoulders (17.8%) in the soft anchor group. Among 37 shoulders evaluated by CT at recurrence, a new glenoid rim fracture was detected in 13 shoulders (35.1%; 5 shoulders in the metal anchor group and 8 shoulders in the soft anchor group). A fracture at the anchor insertion site was recognized in 4 shoulders from the metal anchor group and 6 shoulders from the soft anchor group, although linear fractures connecting several anchor holes were only seen in the soft anchor group. While new glenoid fractures occurred regardless of the number of suture anchors used, new fractures were significantly more frequent in teenagers at surgery and in junior high school or high school athletes. Such fractures did not only occur in contact athletes but were also found in overhead athletes. Conclusion: Postoperative recurrence of instability associated with a new glenoid rim fracture along the suture anchor insertion site was frequent after arthroscopic Bankart repair. These fractures might be related to placing multiple soft suture anchors in a linear arrangement.

Mechanical Properties of an Adjustable-Loop Cortical Suspension Device for Anterior Cruciate Ligament Reconstruction

Background: Various biomechanical properties of adjustable-loop cortical suspension devices have been observed among previous studies in which different experimental conditions were used to test each of these devices. However, no studies have investigated the biomechanical properties of single adjustable-loop cortical suspension devices under different cyclic loading protocols. It is necessary to clarify the problems associated with using this device and detect the best method of using it in the clinical setting. Hypothesis: The elongation of the loop of an adjustable-loop cortical suspension device with cyclic loading would be smaller with (1) an increase in the lower force limit and (2) lower speeds of cyclic loading. Study Design: Controlled laboratory study. Methods: Eighteen anterior cruciate ligament (ACL) adjustable-loop cortical suspension devices were tested under the following 3 cyclic loading protocols in a device-only model. Protocol A included cyclic loading between 10 and 50 N at 50 mm/min for 500 cycles. The upper force limit was then increased by 25-N increments every 500 cycles up to 250 N, for a total of 4500 cycles. Protocol B included cyclic loading between 30 and 50 N at 50 mm/min for 500 cycles. The upper force limit was then increased to 250 N, for a total of 4500 cycles, in the same manner as protocol A. Protocol C included cyclic loading between 30 and 50 N at 25 mm/min for 500 cycles. The upper force limit was then increased to 250 N, for a total of 4500 cycles, in the same manner as protocol A. Results: The elongation after 4500 cycles was 36.1, 18.5, and 8.6 mm for protocols A, B, and C, respectively. There were significant differences among the 3 protocols, with protocol C showing the smallest elongation with cyclic loading. The elongation in each group progressed with each 25-N cyclic load increment. Conclusion: The adjustable-loop cortical suspension device showed a smaller elongation of the loop with increases in the lower force limit and with lower cyclic loading speeds. Clinical Relevance: Care should be taken during rehabilitation after anatomic ACL reconstruction using adjustable-loop cortical suspension devices with a low initial tension at graft fixation. Slow and less intense exercises may be more desirable in the early stages of healing.

Excursion of bone-patella tendon-bone grafts during the flexion–extension movement in anterior cruciate ligament reconstruction: Comparison between isometric and anatomic reconstruction techniques

Background/objective The purpose of this study was to elucidate the biomechanical differences between anterior cruciate ligament (ACL) grafts reconstructed by isometric and anatomic reconstruction techniques, based on their length changes. Methods One hundred and thirty-three knees with primary ACL reconstruction using the bone-patellar tendon-bone (BTB) graft were retrospectively identified. Twenty-two knees and 111 knees underwent isometric round tunnel (IRT) ACL reconstruction and anatomic rectangular tunnel (ART) ACL reconstruction, respectively. Results After femoral-side fixation of the graft in the surgery, the length change of the graft from 120° flexion to full extension was measured by using an isometric positioner at the tibial side. Both reconstructive techniques showed little length change from 120° to ∼20° of flexion, followed by elongation of the graft, until full extension. The amount of length change of the grafts was 1.0 ± 0.7 mm with the IRT technique, and 3.4 ± 0.9 mm with the ART technique. These findings were significantly different, based on the Mann–Whitney U test (p < 0.001). Conclusion The native ACL has an intrinsic length change of 3–6 mm, and therefore the ART technique may more closely replicate the biomechanical function of the native ACL.