Meniscal Circumferential Fiber Augmentation: A Biomechanical Arthroscopic Meniscal Repair Technique.

Radial tears of the human knee meniscus result in the loss of circumferential hoop stress and are highly correlated with knee degeneration. Although a variety of surgical techniques are available to repair radial meniscal tears, including inside-out, outside-in, and all-inside techniques, conventional repair techniques focus only on stabilizing the damaged portion. This Technical Note describes a biomechanical meniscus repair technique of meniscal circumferential fiber augmentation, concomitant with conventional repair, to promote meniscal healing from a biomechanical perspective.

Deep Infection After Anterior Cruciate Ligament Reconstruction Diagnosed by Intratunnel Suspensory Fixation Device Migration: A Case Report.

CASE: A 43-year-old woman sustained an anterior cruciate ligament injury while kickboxing and underwent anterior cruciate ligament reconstruction with hamstring autograft with suspensory fixation. Lateral thigh wound was superficially infected at 2 weeks postoperatively with resolution of signs and symptoms after debridement. Three months later, posterolateral knee pain developed and radiographs revealed intratunnel migration of the device. That observation with abnormal magnetic resonance imaging and serology results led to the diagnosis of deep infection. Immediate device removal and debridement were performed. Consequently, the grafts were preserved, and the patient could perform kickboxing 2 years thereafter. CONCLUSIONS: Intratunnel migration of suspensory fixation devices can support a diagnosis of infection.

Is preoperative glenoid defect size a reliable indicator of postoperative recurrence after arthroscopic Bankart repair in teenage competitive athletes?

BACKGROUND: Being younger than 20 years of age at the time of arthroscopic Bankart repair (ABR) is known to be one of the most important risk factors for postoperative recurrence of instability. When deciding on the appropriate surgical approach, surgeons generally consider only the size of a critical glenoid defect, and most of them do not take into account factors such as the size of bone fragments and possible bone union after arthroscopic bony Bankart repair (ABBR). Therefore, this retrospective study aimed to clarify the risk factors for postoperative recurrence after ABR in teenage competitive athletes by focusing on glenoid rim morphologies and bone union. METHODS: Participants were 115 teenage competitive athletes without a capsular injury who underwent primary ABR for chronic traumatic anterior instability and were followed up for a minimum of 2 years. Possible risk factors for postoperative recurrence were investigated by univariate and multivariate analysis. In shoulders with a glenoid defect and bone fragment, the influence of glenoid defect size and bone fragment size on bone union after ABBR was also investigated. RESULTS: Postoperative recurrence was seen in 16 patients (13.9%). Regarding glenoid defect size, recurrence was seen in 1 (3.2%) of 31 shoulders with a glenoid defect smaller than 5% (including those with a normal glenoid), 15 (22.1%) of 68 shoulders with a glenoid defect of 5%-20%, and 0 (0%) of 16 shoulders with a glenoid defect of 20% or larger (P = .009). Regarding bone union, recurrence was seen in 4 (6.9%) of 58 shoulders with complete or partial bone union after ABBR and 8 (40%) of 20 shoulders with nonunion or disappearance of the bone fragment (P = .001). Regarding bone fragment size, recurrence was seen in 12 (20.7%) of 58 shoulders with a small or no bone fragment (<7.5%) and in 3 (8.6%) of 35 shoulders with a large bone fragment (≥7.5%; P = .154). Multivariate analysis identified non-union or disappearance of the bone fragment after ABBR as a significant risk factor for recurrence. Complete or partial bone union was seen in 25 (58.1%) of 43 shoulders with a small bone fragment (<7.5%) and 33 (94.3%) of 35 shoulders with a large bone fragment (≥7.5%; P < .001). CONCLUSIONS: In teenage competitive athletes, bone union after ABBR affects postoperative recurrence after ABR, regardless of the preoperative glenoid defect size, and bone union rate after ABBR is significantly influenced by bone fragment size.

New bone formation after arthroscopic Bankart repair for unstable shoulders with an erosion-type glenoid defect.

BACKGROUND: The purpose of the present study was to retrospectively evaluate new bone formation after arthroscopic Bankart repair (ABR) and the influence of new bone formation on recurrence in shoulders with an erosion-type glenoid defect. METHODS: We analyzed data on shoulders with an erosion-type glenoid defect. Participants were patients who underwent computed tomography to evaluate new bone formation after ABR performed from 2004 to 2021 and were followed for a minimum of 2 years. We investigated the factors influencing new bone formation, in particular the presence of an intraoperative bone fragment, and the influence of new bone formation and its size on postoperative recurrence. RESULTS: A total of 100 shoulders were included. The mean glenoid defect size was 10.1% ± 6.3% (range, 1.2%-31.5%). New bone formed postoperatively in 15 shoulders (15.0%) and was seen in significantly more shoulders with an intraoperative bone fragment (11 of 18, 61.1%) than in those without a fragment (4 of 82, 4.9%; P < .001). Recurrence occurred in 22 shoulders (22.0%), and the rate of recurrence was not different between shoulders with new bone formation (3 of 15, 20.0%) and without new bone formation (19 of 85, 22.4%; P = .999). Among the 15 shoulders with new bone formation, the size of the new bone fragments relative to glenoid width was <5% in 2 shoulders, 5%-<7.5% in 8 shoulders, 7.5%-<10% in 3 shoulders, and ≥10% in 2 shoulders; in all 3 shoulders with postoperative recurrence, the relative size was <7.5%. CONCLUSIONS: Even in shoulders with an erosion-type glenoid defect, new bone may form after ABR, especially in shoulders with an intraoperative bone fragment. However, new bone formation does not decrease the rate of postoperative recurrence.

Knot location in arthroscopic inside-out meniscal repair: Cadaveric evaluation.

BACKGROUND: The inside-out repair technique is the gold standard for treatment of meniscal tears, while some soft tissues can be hung as the sutures are tied outside the capsule. The purpose was to clarify the association between the suture site and knot location in the arthroscopic inside-out technique. METHODS: Inside-out meniscal suture was arthroscopically performed on medial and lateral menisci in twenty-three cadaveric knees, on the assumption that longitudinal tear existed. A retractor was inserted above the semi-membranous tendon and anterior to the gastrocnemius for the medial side, while the retractor was placed in the anterior space of the gastrocnemius for the lateral side. After identifying three segments (anterior, middle and posterior segments), eight sutures were inserted into the following eight areas in each knee: anterior (M1, L1) and posterior (M2, L2) areas of the middle segment, and anterior (M3, L3) and posterior (M4, L4) areas of the posterior segment. Twelve knees underwent meniscal repair on femoral side and eleven passed sutures on the tibial side, while knots were tied outside of the joint. Attentive dissection was performed to assess the relation between knot locations and the principal structures around the knee joint. RESULTS: In medial meniscal suture, most sutures for the middle portion (M1, 2) bound medial collateral ligament (MCL), while a few cases included the semi-membranous tendon for the M4 area. In lateral meniscal suture, sutures for the L1 area tied some fibers of lateral collateral ligament (LCL) in high frequency, while popliteal muscles/tendons were tied over at the L3 area. CONCLUSIONS: Most suture knots were located on MCL or capsule in medial meniscus suture, while more than half sutures passed through LCL or popliteal tendon/muscle in lateral meniscus suture. An assistant should retract LCL under direct observation and the surgeon must confirm the direction of needle for lateral meniscal repair.

Unrecognized glenoid fracture in opposite shoulders with symptomatic anterior instability.

BACKGROUND: The purpose of the present study was to investigate the characteristics of unrecognized glenoid fracture in opposite shoulders with symptomatic anterior instability. METHODS: Participants were 38 patients, who had complaints of instability on only one side (symptomatic shoulder) and had no complaints despite of a glenoid fracture on the other shoulder (asymptomatic shoulder) from 2011 to 2020. Factors that could influence the onset of symptoms including glenoid rim morphology were retrospectively investigated. RESULTS: Among the asymptomatic shoulders, 16 had a single traumatic event and 22 had no history of trauma. The glenoid morphology was normal in 6, erosion in 12 and bony Bankart in 20 on the symptomatic side, whereas the respective shoulders were 0, 16 and 22 on the asymptomatic side. Bone union of bony Bankart was complete in 9, partial in 3 and non-union in 8 on the symptomatic side, whereas the respective shoulders were 18, 3 and 1 on the asymptomatic side. The mean glenoid defect size was 10.4% and 7.8%, and the mean bone fragment size was 5.0% and 4.5%, respectively. The mean medial displacement of bone fragments was 2.6 mm and 1.0 mm, respectively (p < 0.001). A larger glenoid defect (≥10%) was recognized in 19 symptomatic shoulders and 10 asymptomatic shoulders. Among them, erosion was solely recognized in 5 symptomatic shoulders. In shoulders with bony Bankart, all 10 asymptomatic shoulders had a completely or partially united fragment with less than 2 mm displacement. On the other hand, among 14 symptomatic shoulders, united fragment was solely recognized in 8 shoulders, in which medial displacement was less than 2 mm in 3 shoulders. CONCLUSIONS: Even if a glenoid fracture occurred, symptom such as instability or pain was not always recognized by all patients. Regardless of glenoid defect size, shoulders with a completely or partially united bone fragment and with less than 2 mm displacement were found to be asymptomatic.

The process of bone union after arthroscopic bony Bankart repair in younger athletes with a subcritical glenoid defect: An advantage of remained large bone fragment.

BACKGROUND: The purpose of the present study was to investigate the bone union process after arthroscopic bony Bankart repair (ABBR) in shoulders with a subcritical glenoid defect of 13.5% or larger. METHODS: Bone union process after ABBR performed from 2011 to 2018 were retrospectively investigated in 47 athletes younger than 30 years with a subcritical glenoid defect, who underwent CT at least twice postoperatively. The change of bone union between first CT within 6 months and final CT later than 6 months was investigated, especially noticing bone fragment size (≥7.5% versus <7.5%). RESULTS: The mean period at first CT and at final CT was 4.1 ± 0.6 months (3-6 months) and 16.8 ± 11.6 months (7-71 months), respectively. From the first to final CT, among 15 shoulders with a small bone fragment (<7.5%), complete union increased from 4 shoulders (26.7%) to 8 shoulders (53.3%), while among 32 shoulders with a large bone fragment (≥7.5%), complete union increased from 15 shoulders (46.9%) to 25 shoulders (78.1%). On the other hand, while non-union or disappeared bone fragment was recognized in 8 shoulders (53.3%) with a small fragment and in 2 shoulders (6.3%) with a large fragment at first CT, it was solely recognized in 4 shoulders (26.7%) with a small fragment and in no shoulders with a large fragment at final CT. While postoperative glenoid fracture at the site of bone union was recognized in 7 shoulders, complete union was finally obtained after conservative treatment in 5 shoulders. So, final complete union was obtained in 9 (60%) of 15 shoulders with a small fragment and in 29 (90.6%) of 32 shoulders with a large fragment (p = 0.021). CONCLUSIONS: In shoulders with a subcritical glenoid defect, when a large bone fragment (≥7.5%) was repaired, complete union rate was higher and complete union could be obtained earlier.

Meniscal Displacement and Loss of Load-Transmission Function After Radial Tear of the Lateral Meniscus in a Porcine Model: New Insights Into the Functional Dynamics of the Injured Meniscus.

BACKGROUND: Meniscal extrusion/translation has been used as an index for meniscal treatment. However, the relationship between meniscal displacement and the degree of meniscal tear or load-transmission function of the lateral meniscus (LM) remains unclear. PURPOSE: To clarify the relationship between the width of the radial tear of the LM and (1) meniscal displacement or (2) resultant force through the meniscus under axial compressive load in the porcine model. STUDY DESIGN: Controlled laboratory study. METHODS: Eight intact porcine knees with or without a partial radial tear at the midbody of the LM (involving 30%, 60%, or 90% of its width) were investigated. Reflective markers were attached to the outer wall of the anterior, anteromiddle, posteromiddle, and posterior segments of the LM. A 300-N axial load was applied at 2 flexion angles (30° and 60°), and the 3-dimensional forces and trajectories of the knees were recorded. Marker movements were simultaneously tracked using a motion capture camera system. After total meniscectomy of the LM, the recorded knee trajectories were reproduced, and the resultant force through the LM was calculated (a force carried only by the meniscus in response to a load applied to the whole knee joint). RESULTS: At both flexion angles, the change in distance (mean ± SD) between the anterior and posterior markers under load increased significantly more in the anteroposterior direction in LMs with a 90% tear than in intact LMs (30°, 0.4 ± 0.3 vs 1.4 ± 0.8 mm, P = .004; 60°, 0.1 ± 0.7 vs 1.4 ± 1.0 mm, P < .001 [intact vs 90% tear]). The change in distance between the anteromiddle and posteromiddle markers at 30° also significantly increased in LMs with a 90% tear (0.2 ± 0.2 vs 1.3 ± 1.2 mm, P = .02 [intact vs 90% tear]). The resultant force was significantly lower in LMs with a 90% tear than in intact LMs (30°, 125 ± 47 vs 48 ± 20 N, P < .001; 60°, 93 ± 46 vs 43 ± 11 N, P = .002 [intact vs 90% tear]). We found no significant differences in either meniscal displacements or resultant forces between intact LMs and those with 30% or 60% tears. CONCLUSION: LMs with a 90%-width midbody radial tear lost load-transmission function with their displacement relative to the tibia primarily in the anteroposterior direction in the porcine model. CLINICAL RELEVANCE: Even 1 mm of displacement after meniscal injury is evidence that the load-transmission function of the meniscus is greatly impaired. When a displaced torn LM is diagnosed in preoperative imaging, meniscal repair surgery should be considered.

Remaining Large Bone Fragment of a Bony Bankart Lesion in Shoulders With a Subcritical Glenoid Defect: Association With Recurrent Anterior Instability.

BACKGROUND: A preoperative glenoid defect of 13.5% or larger is recognized as a subcritical glenoid defect at arthroscopic Bankart repair (ABR) for collision/contact athletes or military personnel. PURPOSE: To clarify the prevalence and size of remaining bone fragments in shoulders with a subcritical glenoid defect at recurrent anterior instability and to investigate the influence on postoperative recurrence after ABR for younger competitive athletes. STUDY DESIGN: Cohort study; Level of evidence, 4. METHODS: The study included 96 shoulders with recurrent instability that underwent ABR between July 2011 and March 2018 for shoulders with a subcritical glenoid defect. The patients were divided into 2 groups according to the glenoid defect size (13.5%-<20%, medium; ≥20%, large). The bone fragment size in each defect group was retrospectively investigated and classified into 4 groups (no, 0%; small, >0%-<5%; medium, 5%-<10%; large, ≥10%). The postoperative recurrence rate for each combination of glenoid defect size and bone fragment size was investigated for competitive athletes aged <30 years. The fragments, when present, were repaired to the glenoid. RESULTS: The glenoid defect size was 13.5%-<20% in 60 shoulders (medium defect group) and ≥20% in 36 shoulders (large defect group). The mean bone fragment size was 6.7% ± 5.1% and 8.9% ± 4.9%, respectively (P = .042). In the medium defect group, there were 15 shoulders (25%) without a bone fragment, 6 shoulders (10%) with a small fragment, 23 shoulders (38.3%) with a medium fragment, and 16 shoulders (26.7%) with a large fragment. In the large defect group, the respective numbers were 2 shoulders (5.6%), 6 shoulders (16.7%), 14 shoulders (38.9%), and 14 shoulders (38.9%). A medium or large bone fragment was more common in the large defect group (P = .252). Among 64 younger competitive athletes who underwent ABR with a minimum of 2 years of follow-up, postoperative recurrence was recognized in 7 of 38 (18.4%) athletes in the medium defect group, but it was not recognized in any of the 26 athletes in the large defect group (P = .036). Postoperative recurrence was recognized in 4 of 12 (33.3%) athletes with a small fragment or no fragment and in 3 of 52 (5.8%) athletes with a medium or large fragment (P = .019). CONCLUSION: A larger bone fragment frequently remained in shoulders with a subcritical glenoid defect at recurrent instability. The postoperative recurrence rate after ABR for younger competitive athletes was low when a remaining larger bone fragment was repaired.

The lateral meniscal extrusion after repair with concomitant anterior cruciate ligament reconstruction at a mean follow-up of 3.5 years.

BACKGROUND: A meniscal repair is often performed on radial/flap or longitudinal tears of the lateral meniscus (LM) combined with anterior cruciate ligament reconstruction (ACLR). However, it is unknown if meniscal extrusion changes over time after repair. This study evaluated whether meniscal extrusion of the LM is maintained after repair or progresses with time using magnetic resonance imaging (MRI). METHODS: Among 574 patients who underwent primary anatomic ACLR, 123 patients followed up for more than 2 years were retrospectively analyzed. Forty patients with concomitant radial/flap tears of the LM (group R), 43 with longitudinal LM tears (group L), and 40 with intact LM (group C, matched-control group) were included. Clinical findings (pain, range of motion, swelling, and anterior laxity), lateral joint space on radiograph, and meniscal extrusion on MRI were assessed. Lateral/posterior meniscal extrusions were examined preoperatively, within 3 weeks after surgery, and at the final follow-up, and the absolute values and relative values (the preoperative values as baseline) were assessed respectively. RESULTS: There were no significant differences in the clinical and roentgenographic findings among the groups. No difference was observed in the relative values within 3 weeks after surgery among three groups, although the absolute values were larger in the repaired groups than in group C. At the final follow-up, however, the lateral extrusion in group L had progressed significantly, compared with that in group C (P = 0.033), while no significant difference was detected in the lateral extrusion between groups R and C (P = 0.177). The posterior extrusion in groups R and L had progressed significantly compared with that in group C (P < 0.001). CONCLUSIONS: LM extrusion could not be improved even immediately after meniscal repair, and it progressed laterally and posteriorly for more than 2 years after surgery.

On-the-Edge Anchor Placement May Be Protective Against Glenoid Rim Erosion After Arthroscopic Bankart Repair Compared to On-the-Face Anchor Placement.

PURPOSE: This retrospective study aimed to compare the effects of 2 different anchoring placements on glenoid rim erosion after arthroscopic Bankart repair (ABR). METHODS: Shoulders that underwent ABR from January 2013 to July 2020 were divided into 2 groups according to anchor placement (on-the-face, group F; on-the-edge, group E). We retrospectively calculated the percent change of glenoid width (Δ) on the first postoperative computed tomography scan (CT; performed within 6 months) and second postoperative CT (performed at 6 to 12 months) relative to the width on the preoperative CT and compared percent changes between the 2 groups. Also, we investigated the influence of preoperative glenoid structures (normal, erosion, bony Bankart) and the postoperative recurrence rate. RESULTS: We examined 225 shoulders in 214 patients (group F, n = 151; group E, n = 74). At first CT, anchoring placement was significantly associated with postoperative decrease of glenoid width (group F, -7.6% ± 7.9%; group E, -0.1% ± 9.7%; P < .0001). The difference between groups F and E was significant in shoulders with a preoperative glenoid defect (bony Bankart, -6.6% ± 8.8% vs 2.5% ± 11.2%, respectively; P < .0001; erosion, -6.6% ± 6.2% vs -2.6% ± 5.3%, respectively; P = .03). In 112 shoulders, CT was performed twice; Δ was -6.9% ± 7.3% in group F (n = 64) and -1.7% ± 10.1% in group E (n = 48; P = .005) at the first CT and -3.2% ± 10.0% and 1.0% ± 10.6% (P = .10), respectively, at the second CT, indicating recovery of glenoid width in both groups. The postoperative recurrence rate in patients with at least 2 years' follow-up was 14.7% in group F and 14.6% in group E. CONCLUSIONS: In the early stage after ABR, on-the-edge glenoid anchor placement was associated with less glenoid rim erosion than on-the-face anchor placement. LEVEL OF EVIDENCE: Level III, retrospective comparative trial.

A Glenoid Defect of 13.5% or Larger Is Not Always Critical in Male Competitive Rugby and American Football Players Undergoing Arthroscopic Bony Bankart Repair: Contribution of Resultant Large Bone Fragment.

PURPOSE: To investigate bone union and postoperative recurrence after arthroscopic bony Bankart repair (ABBR) in male competitive rugby and American football players with a subcritical glenoid defect of ≥13.5% and to compare findings with those in players with a glenoid defect of <13.5%. METHODS: Participants were male competitive rugby or American football players with a glenoid defect and bone fragment who underwent ABBR from July 2011 to December 2018 and were followed for a minimum of 2 years. We investigated the influence of glenoid defect and bone fragment size on bone union and postoperative recurrence after ABBR. RESULTS: We included 45 rugby players and 35 American football players. A total of 38 shoulders were assigned to the small defect group (<13.5%) and 42 to the large defect group (≥13.5%). The complete bone union rate was 47.4% in the small defect group and 71.4% in the large defect group (P = .040), and postoperative recurrence was seen in 13 (34.2%) and 5 shoulders (11.9%), respectively (P = .030). In the small defect group, the bone fragment size was <7.5% in 30 shoulders and ≥7.5% in 8 shoulders; in comparison, the respective numbers were 12 and 30 shoulders in the large defect group, and large fragments (>7.5%) were significantly more common in this group (P < .001). The complete union rate was significantly higher in shoulders with a large fragment (≥7.5%) than in those with a small fragment (<7.5%; 78.9% versus 42.9%, respectively; P = .001). The recurrence rate was 33.3% in shoulders with a small fragment (<7.5%) and 10.5% in shoulders with a large fragment (≥7.5%; P = .017) and was significantly lower in shoulders with a complete union than in those without a complete union (6.3% versus 46.9%, respectively; P < .001). CONCLUSION: The postoperative recurrence rate after ABBR was lower in male competitive rugby and American football players with a large glenoid defect (≥13.5%) than in those with a small glenoid defect (<13.5%) and might be associated with a higher rate of complete bone union of the resultant large bone fragment (≥7.5%). LEVEL OF EVIDENCE: III, case-control study.

Suture Slippage During Anterior Cruciate Ligament Graft Passage Is Significantly Lower Using a Krackow Suture.

PURPOSE: To compare the suture slippage on a hamstring tendon graft prepared with a modified finger-trap device (SPEEDTRAP) with one prepared with Krackow stitch during graft passage through the tibial tunnel in ACL reconstruction. METHODS: Thirty-eight patients underwent anatomic triple-bundle anterior cruciate ligament reconstruction with 2 femoral and 3 tibial tunnels. After semitendinosus tendon was cut in half to make 2 grafts, the free ends of the proximal membranous portion (posterolateral [PL] graft) were prepared together with 2 sutures: (1) one SPEEDTRAP and one Krackow stitch for 20 cases (group A) and (2) double Krackow stitches on both sides for 18 cases (group B). Then, the PL graft was dye-marked at the proximal suture of SPEEDTRAP in group A and Krackow suture in group B and was inserted into the joint via tibial tunnel ahead of the loop side. The distance between the mark on the graft and the proximal suture of SPEEDTRAP or Krackow stitch was measured under arthroscopy after graft fixation at femur. Slippage was defined as 1 mm and more of distance between the mark and the proximal suture. RESULTS: Slippage was observed in 16 cases for SPEEDTRAP and in 2 for Krackow suture in group A, whereas one case showed slippage in group B. The slippage distance was 4.0 ± 2.9 mm for SPEEDTRAP and 0.2 ± 0.5 mm for Krackow stitch in group A (P < .001), whereas it was 0.1 ± 0.2 mm for double Krackow stitch in group B, showing a significant difference from SPEEDTRAP suture (P < .001). CONCLUSIONS: At the time of PL graft passage through the tibial tunnel in anterior cruciate ligament reconstruction, there was significantly less slippage observed with the Krackow stitch compared with the SPEEDTRAP stitch. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Outcomes More Than 2 Years After Meniscal Repair for Longitudinal Tears of the Lateral Meniscus Combined With Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Meniscal function after repair of longitudinal tears of the lateral meniscus (LM) with anterior cruciate ligament reconstruction (ACLR) has not been comprehensively investigated. PURPOSE: To evaluate not only the clinical outcomes and radiographic findings of patients who underwent repair of longitudinal tears of the LM combined with ACLR but also the healing status of the repaired meniscus and changes in chondral status with second-look arthroscopy. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Among 548 patients who underwent primary anatomic ACLR at our institution between 2010 and 2017, 39 who had concomitant longitudinal tears of the LM and underwent repair were studied. During follow-up for more than 2 years, all patients were evaluated clinically (pain, range of motion, swelling, and knee instability) and with imaging (plain radiograph and magnetic resonance imaging [MRI]), and compared with a matched control group (based on age, sex, body mass index, and follow-up period) without any concomitant injuries who underwent ACLR. Measurements on MRI were recorded preoperatively, immediately after surgery, and at final follow-up, and the change in the values over time was assessed. Of the 39 patients in each group, 24 were assessed by second-look arthroscopy with hardware removal 2 years postoperatively. RESULTS: The mean follow-up times of the study and control group were at a mean of 42.4 and 45.4 months, respectively. There were no significant differences in clinical findings, lateral joint space narrowing on radiographs, and chondral status at the lateral compartment between groups, whereas lateral and posterior meniscal extrusion on MRI progressed significantly in the study group (0.43 ± 1.0 mm vs -0.29 ± 1.1 mm, P = .003; 1.9 ± 1.9 mm vs 0.14 ± 1.1 mm, P < .0001, respectively). Second-look arthroscopy revealed complete healing in 12 patients (50%), partial healing in 9 (37.5%), and failure in 3 (12.5%) in the study group, and no new tear in the control group. CONCLUSION: The clinical and imaging outcomes after repair of longitudinal tears of the LM combined with anatomic ACLR were successful and comparable with those after isolated ACLR without any other injuries at 42 months postoperatively, although meniscal extrusion showed progression on coronal/sagittal MRI. Based on the MRI findings and the result that only half of patients achieved complete healing, meniscal function could not be fully restored even after repair. Although degenerative changes were not apparent, longer-term follow-up is needed.

Comparison of tendon-bone healing between a newly developed ultrasound device and the conventional metallic drill in a rabbit MCL reconstruction model.

BACKGROUND: Ligament reconstructive surgeries demand tunnel creation using an over-drilling technique, though this technique has some problems such as metallic particle liberation or difficulties in tunnel creation other than circular cross-section. Recently, a new ultrasound (US) device for bone excavation to overcome these problems was developed. This study aimed to compare the tendon-bone healing in tunnels created using the new US device to that created using the conventional drill in a rabbit model. METHODS: A total of 72 rabbits underwent a reconstruction for the anterior half of the medial collateral ligament (MCL) using a half of the patellar tendon. For the femoral tunnel creation, a new US device was used in 36 rabbits (US group), while a conventional metallic drill was used for the remaining 36 rabbits (DR group). At 4, 8, and 12 weeks postoperatively, biomechanical (n = 10) and histological (n = 2) evaluations were performed. RESULTS: The ultimate failure load was almost equivalent between the US and DR groups at each period (US/DR; 4 weeks, 50.0 ± 12.8 N/43.4 ± 18.9 N, p = 0.62; 8 weeks, 78.6 ± 11.5 N/77.3 ± 29.9 N, p = 0.92; and 12 weeks: 98.9 ± 33.5 N/102.2 ± 38.3 N, p = 0.80). Pull-out failure from the femoral tunnel was only observed in two rabbits in the US group and one rabbit in the DR group at 4 weeks postoperatively. At 8 and 12 weeks, all specimens had a mid-substance tear. The collagen fiber continuity between tendon and bone occurred 8 weeks postoperatively in both groups and no histological difference was recognized throughout the evaluation period. CONCLUSIONS: The tunnels created using the new US device and the conventional drill had equivalent biomechanical and histological features in tendon-bone healing. The bone excavation technology by the new US device may be applicable in ligament reconstructive surgeries.

Different effects of the lateral meniscus complete radial tear on the load distribution and transmission functions depending on the tear site.

PURPOSE: To compare the effect of the lateral meniscus (LM) complete radial tear at different tear sites on the load distribution and transmission functions. METHODS: A compressive load of 300 N was applied to the intact porcine knees (n = 30) at 15°, 30°, 60°, 90°, and 120° of flexion. The LM complete radial tears were created at the middle portion (group M), the posterior portion (group P), or the posterior root (group R) (n = 10, each group), and the same loading procedure was followed. Finally, the recorded three-dimensional paths were reproduced on the LM-removed knees. The peak contact pressure (contact area) in the lateral compartment and the calculated in situ force of the LM under the principle of superposition were compared among the four groups (intact, group M, group P, and group R). RESULTS: At all the flexion angles, the peak contact pressure (contact area) was significantly higher (lower) after creating the LM complete radial tear as compared to that in the intact state (p < 0.01). At 120° of flexion, group R represented the highest peak contact pressure (lowest contact area), followed by group P and group M (p < 0.05). The results of the in situ force carried by the LM were similar to those of the tibiofemoral contact mechanics. CONCLUSION: The detrimental effect of the LM complete radial tear on the load distribution and transmission functions was greatest in the posterior root tear, followed by the posterior portion tear and the middle portion tear in the deep-flexed position. Complete radial tars of the meniscus, especially at the posterior root, should be repaired to restore the biomechanical function.

Reduction of in situ force through the meniscus with phased inner resection of medial meniscus: an experimental study in a porcine model.

PURPOSE: Partial meniscectomy can cause osteoarthritic changes in knees, as inner portion as well as peripheral portion of meniscus is important. The hypothesis of this study was that the amount of the inner resection of medial meniscus affected the in situ forces through the meniscus and the tibial varus and external rotation under axial load. METHODS: Fourteen intact porcine knees were investigated with a six-degree of freedom robotic system and force/moment, and the three-dimensional path of intact knees were recorded by universal force sensor when an axial load of 300-N was applied at four different flexion angles (30°, 60°, 90°, and 120°). The same examination was performed on three phased inner resections (30%, 60%, and 90% width) of the medial meniscus. Finally, all paths were reproduced after total medial meniscectomy, and in situ forces of the medial meniscus were calculated based on the superposition principle. Changes in tibiofemoral varus/valgus and internal/external rotation alignment during an axial load were also calculated. RESULTS: In situ forces of the medial meniscus decreased according to the amount of meniscal resection at all flexion angles. The reduction was significant in knees with inner resections of > 60% width at all flexion angles and even of 30% width at a flexion angle of 120° (p < .05). Incremental changes in the tibiofemoral varus alignment increased depending on the inner resection width at all flexion angles (p < .05). CONCLUSION: The amount of inner resection of the medial meniscus was related to reduction of its in situ forces and increment of the tibial varus rotation under axial load.

Residual graft tension after graft fixation in anterior cruciate ligament reconstruction: Manual vs tensioning boot techniques.

BACKGROUND: Graft fixation at quantitative tension using a manual tensioner was advocated in ACL reconstruction, while the measured tension that is based on the surgeon's hand with the tensioner decreases after graft fixation. Therefore, our purpose is to elucidate how effectively the pre-determined graft tension maintained after final fixation of the graft to the tibia using a tensioning boot system fixed to the calf with a bandage, while monitoring the graft tension based on tibia. METHODS: Eight cadaveric legs (mean age: 83; 3 males and 5 females) underwent an anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with hamstring tendon grafts. Two tension-adjustable force gauges were installed on the lateral femoral cortex beside the femoral tunnel. Then #5 strong suture wires through the loop end of grafts were tied to the force gauges using Endo-Buttons. After manual maximum load was repeatedly applied to each graft for 3 min, the grafts were fixed to the tibia with 10 N or 20 N at 20 degree of flexion with the following tensioning techniques using double spike plate system: (1) Manually tensioning technique (MT); (2) Tensioning boot technique with flexion-extension motion (TB-FE); and (3) Tensioning boot technique with repetitive pull (TB-RP). The residual tension at 20 was measured 3 min after grafts fixation, and also after 10 and 50 times of repeated flexion-extension motion. One-way repeated measures ANOVA was used for statistical analysis among the three techniques. RESULTS: There were significant differences among three techniques fixing grafts with 10/20 N of initial tension in the residual tension 3 min after graft fixation and after 10 and 50 times of repeated flexion-extension motion. Among them, the residual tension in TB-RP was the greatest in most conditions. CONCLUSION: TB-RP is the most secure procedure to maintain the graft tension closer to the intended initial tension in ACL reconstruction.

Tibial tunnel enlargement after anatomic anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft. Part 2: Factors related to the tibial tunnel enlargement.

BACKGROUND: Factors related to tunnel enlargement after anterior cruciate ligament (ACL) reconstruction should be evaluated by multivariate analysis, because the phenomenon has multifactorial characteristics. The purpose of this study was to elucidate the factors related to the tibial tunnel enlargement rate after anatomic ACL reconstruction with a bone-patellar tendon-bone (BTB) graft using multivariate analysis. METHODS: Eighteen patients with unilateral ACL rupture were included. The anatomic rectangular-tunnel (ART) ACL reconstruction with a BTB autograft was performed. 3D CT models of the tibia, the tibial tunnel, and the bone plug at 3 weeks and 1 year after surgery were reconstructed and superimposed using a surface registration technique. The cross-sectional area (CSA) of the tibial tunnel perpendicular to the tunnel axis was evaluated at the aperture. The CSA was measured at 3 weeks and 1 year after surgery, and the tunnel enlargement rate at the aperture was calculated. Multiple linear regression analysis was performed to detect the significantly related factors to the tibial tunnel enlargement rate at the aperture among potential factors consisting of preoperative demographic factors and predisposing factors with the tibial tunnel. RESULTS: The tibial tunnel enlargement rate at the aperture was 21.9 ± 14.1% (mean ± standard deviation). Multiple linear regression analysis detected the tendon length inside the tunnel as a significantly independent factor related to the tibial tunnel enlargement rate at the aperture (standardized ß = 0.726, P = 0.008). There was no significant relationship between the tibial tunnel enlargement rate at the aperture and postoperative side-to-side difference (SSD) of the anterior knee laxity or Tegner activity level scale under single linear regression analysis. CONCLUSION: The greater tendon length inside the tunnel was independently related to the higher tibial tunnel enlargement rate at the aperture 1-year after anatomic ACL reconstruction with a BTB graft under multiple linear regression analysis.