Comparison of elbow valgus laxity and medial elbow stabilizer parameters during repetitive pitching between high school baseball players with and without a history of medial elbow injury.

BACKGROUND: Adolescent baseball players with a history of medial elbow injury are often reinjured during demanding practice sessions or games. The physical characteristics of baseball players with a history of medial elbow injury have been reported in several previous studies, but the nature of their medial elbow stabilizers is unknown. This study investigated the difference in characteristics of elbow valgus laxity and medial elbow stabilizer parameters between baseball players with and without a history of medial elbow injury, prior to and during repetitive pitching. METHODS: Sixteen high school baseball players with no history of medial elbow injury (No-Injury group) and 14 high school baseball players with a history of medial elbow injury (Injury History group) participated. The participants pitched 100 fastballs. Medial elbow joint-space gapping and strain ratio indicating tissue elasticity of ulnar collateral ligament (UCL) and forearm flexor-pronator muscles (FPMs) were measured by ultrasound before pitching and following each of five 20-pitch blocks. Student t tests and Mann-Whitney U tests were used to compare each parameter between groups. RESULTS: Medial elbow joint-space gapping and UCL elasticity were not significantly different between the 2 groups in each pitching block (P > .05). The strain ratio of FPMs before pitching and after 100 pitches in the Injury History group were significantly greater than that in the No-Injury group (No-Injury vs. Injury History group: before pitching, 0.47 ± 0.19 vs. 0.68 ± 0.26, P = .016; 100 pitches, 0.35 ± 0.12 vs. 0.53 ± 0.20, P = .007). In the other pitching blocks, there was no significant difference between groups, but the effect size was medium and showed a similar tendency (20 pitches, P = .069, Cohen d = 0.69; 40 pitches, P = .116, Cohen d = 0.59; 60 pitches, P = .102, Cohen d = 0.62; 80 pitches, P = .058, Cohen d = 0.72). CONCLUSIONS: The results of this study indicate that FPM elasticity at baseline and during repetitive pitching in players with a history of medial elbow injury was harder than in players without injury history. This may suggest that baseball players with a history of medial elbow injury increase support of their previously injured medial elbow by hardening FPM elasticity to counteract elbow valgus stress generated during pitching, which may lead to long-term change in the FPMs. Therefore, physical management for this change may be important to prevent reinjury in baseball players with a history of medial elbow injury.

Ulnar Collateral Ligament Laxity After Repetitive Pitching: Associated Factors in High School Baseball Pitchers.

BACKGROUND: Medial elbow injury is common in baseball pitchers, with evidence of elbow valgus instability after only 60 consecutive pitches. However, the tissue-specific effects of repetitive pitching on medial elbow stabilizers are largely unknown. PURPOSE/HYPOTHESIS: This study aimed to investigate changes in the ulnar collateral ligament (UCL) and forearm flexor-pronator muscles (FPMs) during repetitive pitching and factors that relate to identified change. We hypothesized that repetitive pitching would increase elasticity of the medial elbow stabilizers and therefore induce laxity. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 30 high school baseball pitchers participated (mean ± SD age, 16.6 ± 0.5 years). Each participant pitched 100 times (5 blocks of 20 pitches). The strain ratio, indicating elasticity in the UCL and FPMs, was measured using ultrasound before pitching and after every 20-pitch block. Data for each pitch block were compared using analysis of variance. Multiple regression analysis was used to investigate factors related to the change rate of the strain ratio. RESULTS: The strain ratio of the UCL after 100 pitches was significantly less than that before pitching (before pitching, 4.83 ± 1.70; after 100 pitches, 3.59 ± 1.35; P = .013), but this was not the case for the FPMs (before pitching, 0.57 ± 0.24; after 100 pitches, 0.43 ± 0.18; P = .07). The ratio of the strain ratio in the UCL and FPMs (UCL/FPMs) before pitching (ß = -0.385; P = .031) and the elbow flexion range of motion before pitching (ß = -0.352; P = .046) were significantly and independently correlated with the change rate of the UCL. CONCLUSION: Elasticity significantly increased for the UCL, indicating laxity, but not for the FPMs after 100 pitches. Furthermore, the ratio of elasticity (UCL/FPMs) and the elbow flexion range of motion before pitching were significantly related to the change rate of UCL elasticity. CLINICAL RELEVANCE: To reduce laxity of the UCL, pitchers should be limited to <100 pitches per game. Sustaining a lower level of relative FPMs to UCL elasticity at rest and maintaining a large muscle volume to avoid excessive elbow flexion range of motion may prevent UCL laxity that develops during repetitive pitching.

Changes in medial elbow elasticity and joint space gapping during maximal gripping: reliability and validity in evaluation of the medial elbow joint using ultrasound elastography.

BACKGROUND: Medial elbow injuries are common in baseball pitchers. This study investigated the reliability of medial elbow elastography measurement and the characteristics of the medial elbow stabilizers. METHODS: Medial elbow joint space gapping and the strain ratios of the ulnar collateral ligament (UCL) and the forearm flexor-pronator muscle (FPM) were measured at rest and during gripping in 29 healthy college students. The intraclass correlation coefficients of elastography were calculated. The data were compared between tissues and between rest and gripping. RESULTS: The intraclass correlation coefficients (ICC1,3) of the elastography measurements were 0.91 and 0.83 for the UCL and 0.80 and 0.85 for the FPM for each examiner. Medial elbow joint space gapping during gripping (3.1 ± 0.6 mm) was significantly less than that at rest (3.8 ± 0.8 mm, P < .001). The strain ratios for both the UCL and FPM during gripping were significantly greater than those at rest (17.64 ± 10.97 during gripping vs. 3.94 ± 1.92 at rest for UCL, P < .001; 1.72 ± 0.99 during gripping vs. 0.35 ± 1.92 at rest for FPM, P < .001). The strain ratio for the UCL was significantly greater than that for the FPM both at rest (P < .001) and during gripping (P < .001). CONCLUSIONS: Elastography measurements of the UCL and FPM have almost perfect reliability. Gripping reduces medial elbow joint space gapping compared with rest. For both tissues, gripping reduces their elasticity compared with rest. The elasticity of the UCL is less than that of the FPM both at rest and during gripping.

Effects of Nordic Hamstring Exercise on Hamstring Injuries in High School Soccer Players: A Randomized Controlled Trial.

We evaluated a range of physical characteristics related to hamstring injuries, as well as the Nordic Hamstring Exercise compliance rate, and whether this influenced the rate hamstring injury. Subjects comprised 259 male soccer players from seven high schools randomly clustered into two groups, a Nordic Hamstring Exercise group and a control group. Training and match time were logged, as well as details of hamstring injury, and subsequent time lost to hamstring injury recorded over a period of 27 weeks. The Nordic Hamstring Exercise compliance rate, injury rate per 10000 playing hours and time-lost-to-sport-injury rate were calculated. The relative risk and hamstring injury severity were also calculated. The hamstring injury rate was 1.04/10 000 h in the control group and 0.88/10 000 h in the intervention group. The relative risk for hamstring injury was 1.14. The time-lost to injury rate was 1116.3/10 000 h in the control group and 113.7/10 000 h in the intervention group; with relative risk 9.81. The Nordic Hamstring Exercise in high school soccer players significantly reduced hamstring injury severity compared to a control intervention. Our results indicate that the time-lost to injury rate should be taken into account when analyzing the severity of hamstring injury.

Effects of tunnel dilation and interference screw position on the biomechanical properties of tendon graft fixation for anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to evaluate the effects of screw position and compaction of the bone tunnel on the strength of the flexor tendon graft after fixation using interference screws. METHODS: Forty fresh-frozen porcine tibias were used for this study. The digital flexor tendons were folded into a quadrupled graft measuring 9 mm in diameter. In the extraction-drilling group, tibial bone tunnels were drilled with a conventional cannulated 9-mm drill bit in a single step. In the compaction-drilling group, bone tunnels were drilled using a cannulated 7-mm drill bit and were expanded to a final diameter of 9 mm in 0.5-mm increments by placement of dilators with increasing diameter. The grafts were fixed using 9 × 30-mm titanium screws in central and eccentric positions. Specimens underwent a cyclic-loading test, and the surviving specimens were then loaded until failure. RESULTS: Graft displacement after 1,500 loading cycles occurred significantly more often in the extraction-drilling group with eccentric screw placement than in the groups of extraction-drilling (P < .05) and compaction-drilling (P < .01) with central screw placement. There were no statistically significant differences for the maximum screw insertion torque, maximum load at failure, or stiffness among the 4 groups. One strand of the quadrupled tendon grafts showed partial injury during screw insertion in 3 (30%) and 4 (40%) of 10 specimens of the extraction-drilling and compaction-drilling groups with central screw placement, respectively. CONCLUSIONS: Central screw placement significantly decreased the displacement of the tendon graft in comparison with eccentric screw placement in the extraction-drilling condition. Compaction of the bone tunnel walls by serial dilation in a central screw position did not increase the strength of interference screw fixation of a soft tissue graft. CLINICAL RELEVANCE: When using the extraction method and fixing the graft in an eccentric position, it is advisable to provide additional fixation outside the tunnel to prevent slippage of the graft.

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.

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.

Intra-articular ganglia arising from the posterior joint capsule of the knee.

Magnetic resonance imaging (MRI) is an effective method to evaluate cystic lesions of the knee. Intra-articular ganglia of the knee joint was considered to be rare before the advent of MRI. However, because an MRI is often used to diagnose knee pathology, the reported prevalence of intra-articular ganglia has increased. We describe two cases of an intra-articular ganglion arising from the posterior joint capsule. Both cysts appeared to be arising from the posterior cruciate ligament by both MRI as well as arthroscopy through a lateral infrapatellar portal. However, arthroscopy through a posteromedial portal revealed the cysts to originate from the posterior joint capsule. It suggests that some of the ganglion arising from the posterior cruciate ligament reported in the literature might actually be from the posterior joint capsule. To prevent recurrence of a ganglion cyst, when preoperative MRI shows the mass to be located posterior to the cruciate ligaments, we recommend that the relationship of the ganglion cyst to the posterior joint capsule be evaluated at arthroscopy through the posteromedial or posterolateral portal.

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.

Tissue response to porous hydroxyapatite ceramic in the human femoral head.

We describe pathohistological findings of the human femoral head after it was grafted with hydroxyapatite (HA) and allogenic bone. The femoral head was removed because of the recurrence of a giant cell tumor 15 months after the graft. Histological investigation revealed that the entire surface of the HA granules was completely surrounded by the bone in the periphery of the grafted area; in some areas granules were partly in contact with the existing bone, and the rest were surrounded by fibrous tissue. There was no intervening layer of fibrous tissue between the granule surface and the bone where they were in direct contact. Pores were completely filled with fibrous tissue, partially filled with bone in the periphery of the pores, or completely filled with bone. Undecalcified histology revealed the formation of osteoid and ossification at the site where fibrous tissue infiltrated the pores. These findings indicated continued ingrowth of new bone into the HA pores. Under a scanning electron microscope, the surfaces of the granules showed clear demarcation in vitro, but it became less smooth, indicating in vivo changes. Although no foreign body reaction to the HA was noted anywhere, the HA surface appeared to be subject to a biodegradation process.

Acetabular labrum entrapment following traumatic posterior dislocation of the hip.

In traumatic dislocation of the hip with or without a fracture of the acetabular rim, complete anatomical reduction might be prevented by a bone fragment or infrequently by a soft tissue block, such as a torn acetabular labrum, ruptured capsule, or round ligament. We report a rare case of a tear in the acetabular labrum that prevented complete reduction of the dislocated hip. A 26-year-old man suffered posterior dislocation of the right hip, which was reduced under general anesthesia. The postreduction radiograph showed that the reduction was not complete, and a thin bony fragment was observed in the joint space in the weight-bearing area. Open reduction was performed 11 days later. We found a free bone fragment in the joint space, which was removed. The postoperative radiograph still did not show complete reduction of the hip. A large defect in the contrast medium was shown in the widened joint space by arthrography, which revealed the existence of the soft tissue interposition. We then performed a second operation and learned that the acetabular labrum was widely detached from the anterior to the posterior acetabular rim and was lying deep within the acetabulum. This detached portion of the labrum was excised, and the hip was reduced. The radiograph obtained during surgery then showed complete, concentric reduction. We missed the diagnosis clinically and radiologically at the first operation, proving how important it is to obtain an accurate radiological diagnosis in the operating room.

Vascularized synovial flap promoting regeneration of the cryopreserved meniscal allograft: experimental study in rabbits.

The purpose of this investigation was to evaluate whether a vascularized or free synovial flap or a fibrin clot can promote regeneration of meniscal allograft in the rabbit. Seventy-eight mature New Zealand white rabbits were used. The harvested medial meniscus for the allotransplantation was frozen and stored at -80 degrees C for 2 weeks. After resecting the medial meniscus, an allogenic meniscus was transplanted in the anatomical position (group A). The surface of the graft was covered by a vascularized synovial flap (group B), a free synovial flap (group C), or a fibrin clot (group D). The animals were killed 4, 6, 8, 12, and 16 weeks after transplantation, and the transplants were examined by gross inspection, histology, and microangiography. Connective tissue infiltration into the matrix of the graft was found to begin at 6 weeks (2/5 menisci) and to be complete at 8 weeks (5/5 menisci) in group B, whereas it began at 8 weeks (1/5) in group A. The newly formed repair tissue developed from the synovial tissue and consisted of connective tissue at the beginning and fibrocartilage later. The fibrocartilage had appeared at 8 weeks (3/5) in group B but not yet in group A (0/5). A free flap or fibrin clot coverage resulted in delayed revascularization compared to a vascularized synovial flap, but both tended to achieve faster revascularization than the controls. We concluded that regeneration of allografted meniscus with a vascularized synovial flap occurs earlier than under other conditions. Thus, allografts with synovial implantation may be considered for management of the meniscectomized knee.