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.

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.

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.

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.

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.

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.

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.

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.

A longitudinal tear in the medial meniscal body decreased the in situ meniscus force under an axial load.

PURPOSE: To clarify the effect of longitudinal tears of the medial meniscus on the in situ meniscus force and the tibiofemoral relationship under axial load. METHODS: Twenty-one intact porcine knees were mounted on a 6-degrees of freedom robotic system, and the force and three-dimensional path of the knee joints were recorded during three cycles under a 250-N axial load at 30°, 60°, 90° and 120° of knee flexion. They were divided into three groups of seven knees with longitudinal tears in the middle to the posterior segment of the medial meniscus based on the tear site: rim, outer one-third and inner one-third of the meniscal body. After creating tears, the same tests were performed. Finally, all paths were reproduced after total medial meniscectomy, and the in situ force of the medial meniscus was calculated based on the principle of superposition. RESULTS: With a longitudinal tear, the in situ force of the medial meniscus was significantly decreased at 60°, 90° and 120° of knee flexion, regardless of the tear site. The decrement was greater with a tear in the meniscal body than a tear in the rim. A longitudinal tear in the meniscal body caused a significantly greater tibial varus rotation than a tear in the rim at all flexion angles. CONCLUSION: Longitudinal tears significantly decreased the in situ force of the medial meniscus. Tears in the meniscal body caused a larger decrease of the in situ meniscus force and greater varus tibial rotation than tears in the rim.

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.

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 1: Morphological change in the tibial tunnel.

BACKGROUND: Three-dimensional (3D) computed tomography (CT) is reliable and accurate imaging modality for evaluating tunnel enlargement after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the tibial tunnel enlargement including the morphological change after anatomic ACL reconstruction with a bone-patellar tendon-bone (BTB) graft using 3D CT models. 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 and 5, 10, and 15-mm distal from the aperture. The CSA was measured at 3 weeks and 1 year after surgery and compared between the two time points. The locations of the center and the anterior, posterior, medial, and lateral edges of the tunnel footprint were also evaluated based on the coordinate system for the tibial plateau and compared between the two time points. RESULTS: At the aperture, the CSA of the tibial tunnel at 1 year after surgery was significantly larger by 21.9% than that at 3 weeks (P < 0.001). In contrast, the CSA at 1 year was significantly smaller than that at 3 weeks at 10 and 15-mm distal from the aperture (P = 0.041 and < 0.001, respectively). The center of the tunnel footprint significantly shifted postero-laterally with significant posterior shift of the anterior/posterior edges and lateral shift of the lateral edge (P < 0.001). CONCLUSION: The tibial tunnel enlarged at the aperture by 22% 1-year after anatomic ACL reconstruction with a BTB graft, and the tunnel morphology changed in a postero-lateral direction at the aperture and into conical shape inside the tunnel.

Femoral tunnel enlargement after anatomic anterior cruciate ligament reconstruction: Bone-patellar tendon-bone /single rectangular tunnel versus hamstring tendon / double tunnels.

PURPOSE: This study aimed to prospectively compare the femoral tunnel enlargement at the aperture as well as inside the tunnel after anatomic anterior cruciate ligament (ACL) reconstruction with bone-patellar tendon-bone (BTB) graft to that with hamstring tendon (HST) graft. METHODS: This study included 24 patients with unilateral ACL rupture. Twelve patients underwent anatomic rectangular tunnel (ART) ACL reconstruction with BTB graft and the remaining 12 underwent anatomic triple-bundle (ATB) ACL reconstruction with HST graft. Three-dimensional computer models of femur and bone tunnels were reconstructed from computed tomography images obtained at 3 weeks and 1 year postoperatively. The femoral tunnel enlargement from 3 weeks to 1 year was evaluated by comparing the cross-sectional area (CSA), and compared between the two groups. RESULTS: The CSA in the ART group at 1 year decreased at the aperture as well as inside the tunnel comparing that at 3 weeks. The CSAs of both tunnels in the ATB group at 1 year significantly increased at the aperture in comparison to those at 3 weeks, and gradually decreased toward the inside of the tunnel. The enlargement rate at the aperture in the ART group was -12.9%, which was significantly smaller than that of anteromedial graft (27.9%; P = 0.006) and posterolateral graft (31.3%; P = 0.003) in the ATB group. The tunnel enlargement rate at 5 mm from the aperture in the ART group was also significantly smaller than that in the ATB group. At 10 mm from the aperture, there was no significant difference between the tunnel enlargement rate in the ART group and that of anteromedial tunnel. CONCLUSIONS: The tunnel enlargement rate around the aperture was significantly smaller after the ART procedure than that after the ATB procedure. Thus, BTB graft might be preferable as a graft material to HST graft in the femoral tunnel enlargement.

Effect of radial meniscal tear on in situ forces of meniscus and tibiofemoral relationship.

PURPOSE: To clarify the effect of the radial tear of the lateral meniscus on the in situ meniscus force and the tibiofemoral relationship under axial loads and valgus torques. METHODS: Ten intact porcine knees were settled to a 6-degree of freedom robotic system, while the force and 3-dimensional path of the knees were recorded via Universal Force Sensor (UFS) during 3 cycles of 250-N axial load and 5-Nm valgus torque at 15°, 30°, 45°, and 60° of knee flexion. The same examination was performed on the following 3 meniscal states sequentially; 33, 66, and 100% width of radial tears at the middle segment of the lateral meniscus, while recording the force and path of the knees via UFS. Finally, all paths were reproduced after total lateral meniscectomy and the in situ force of the lateral meniscus were calculated with the principle of superposition. RESULTS: The radial tear of 100% width significantly decreased the in situ force of the lateral meniscus and caused tibial medial shift and valgus rotation at 30°-60° of knee flexion in both testing protocols. Under a 250-N axial load at 60° of knee flexion, the in situ force decreased to 36 ± 29 N with 100% width of radial tear, which was 122 ± 38 N in the intact state. Additionally, the tibia shifted medially by 2.1 ± 0.9 mm and valgusrotated by 2.5 ± 1.9° with the complete radial tear. However, the radial tear of 33 or 66% width had little effect on either the in situ force or the tibial position. CONCLUSION: A radial tear of 100% width involving the rim significantly decreased the in situ force of the lateral meniscus and caused medial shift and valgus rotation of the tibia, whereas a radial tear of up to 66% width produced only little change. The clinical relevance is that loss of meniscal functions due to complete radial tear can lead to abnormal stress concentration in a focal area of cartilage and can increase the risk of osteoarthritis in the future.

Post-operative deformation and extrusion of the discoid lateral meniscus following a partial meniscectomy with repair.

PURPOSE: The purpose of this study was to investigate the morphology of the discoid lateral meniscus sequentially following a partial meniscectomy with repair using magnetic resonance imaging (MRI). METHODS: Nine patients with a symptomatic discoid lateral meniscus with a peripheral tear were enrolled in this study, and a partial meniscectomy with repair was performed arthroscopically. An MRI examination was performed 2 weeks after surgery (before weight bearing was permitted) and again 6 months after surgery (when sporting activities could resume). The width, height and distance of the discoid lateral meniscus were measured. The distance was defined as the distance between the edges of the discoid lateral meniscus and the tibia. RESULTS: The width of the anterior, middle and posterior segments significantly decreased from 2 weeks to 6 months after surgery. The height of the middle and posterior segments significantly increased from 2 weeks to 6 months after surgery, whereas the height of the anterior segment did not significantly change. The distance of the anterior, middle and posterior segments significantly decreased from 2 weeks to 6 months after surgery. CONCLUSION: The discoid lateral meniscus exhibited deformation and extrusion from 2 weeks to 6 months after a partial meniscectomy with repair. Therefore, the function of load transmission might not be maintained appropriately after surgery. LEVEL OF EVIDENCE: IV.

All-inside suture meniscal repair using suture passer.

In recent years, to save the meniscus and prevent the progression of knee osteoarthritis, the indications for meniscus repair have been expanding instead of partial menisectomy. Accordingly, various repair techniques for meniscus tears have been developed. The conventional inside-out and outside-in meniscus repair techniques and all-inside repair technique with an implant/anchor can be classified as trans-capsular (TC) repair from the perspective of suture with penetrating capsule. Recently, new suture passers for all-inside meniscus repair have been developed. To distinguish from conventional all-inside repair with implant/anchors, all-inside repair with only suture using these suture passers was described as all-inside suture (AIS) repair. This AIS repair could achieve meniscus-to-meniscus suture across the tear without interposition of soft tissues including the capsule between suture and meniscus, leading direct gap closing of torn edges. In this respect, AIS repair is considered to be "anatomical meniscus repair". Actually, some reports showed biomechanical and clinical advantages of AIS repair. However, there is still limited evidence in clinical practice. Moreover, there are some disadvantages for AIS repair. Not only further studies but also development of new devices and surgical techniques for AIS should be required. This review describes the current status of AIS repair for each type of tear.

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.