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Background: Open-wedge High Tibial Osteotomy (HTO) is an effective treatment for Osteoarthritis (OA) of the knee; however, postoperative changes due to HTO can make subsequent Total Knee Arthroplasty (TKA) technically difficult and can affect long-term survival. Case Report: Medio-lateral stability along with balanced flexion and extension gaps provides a good functional outcome. A 71-year-old man underwent TKA conversion after open-wedge HTO 12 years earlier; the conversion was performed due to arthritic deterioration in the knee. Medial instability was noted because of poor ligament balancing. The residual medial instability was managed with a knee brace due to the unavailability of the constrained prosthesis. Management of persistent mediolateral instability persisting after soft tissue release and balancing ideally requires varus-valgus constraint. Conclusion: TKA conversion after open-wedge HTO requires a special technique and careful preparation before surgery.

Background: The trapeziometacarpal joint is the second most common site of osteoarthritis in the hand and the most frequent one to require surgery. Arthrodesis of the trapeziometacarpal joint is recognized as one of the valuable technique but unfortunately there has been wide variation in the union rate. The purpose of this study was to evaluate a new arthrodesis technique involving a cross-shaped bone graft and locking plate fixation. Methods: Eleven male patients diagnosed as Eaton’s stage III osteoarthritis of the trapeziometacarpal join were treated in our institute. The mean patient age was 62 years (range 50 to 80 years). At the day after surgery, physical therapy was started and free use of the hand was permitted. Results: Patients showed radiographic evidence of trapeziometacarpal joint union after an average postoperative period of 8.3 weeks (range 6–12 weeks). The VAS pain score significantly decreased from 7.2 points preoperatively to 0.4 points after surgery. Mean side pinch strength increased significantly from 3.8 kg (53% compared to unaffected side) prior to surgery to 6.2 kg (86%). The DASH score improved from 38.6 (range 34.1–43.2) preoperatively to 17.0 (6.8–22.7) postoperatively. Conclusions: These data suggested that our technique is a successful procedure for the trapeziometacarpal joint arthrodesis. Cross-shaped bone grafts have the advantages of restoring thumb length and providing internal stabilization, especially for rotational force. No complications arose at the bone harvest site of the iliac crest. The procedure seems to be technically demanding, particularly for adapting the bone graft to perfectly match the shape of the defect.

Background Evaluation of knee and lower limb function alone is not sufficient to assess gait. For accurate assessment of gait abnormality, gait oscillation should also be measured. The goal of this analysis was to assess the influence of the knee joint on gait oscillation during gait and stair-stepping in patients with osteoarthritis of the knee. Methods In 33 patients diagnosed with knee osteoarthritis and 33 healthy adults as the control group, we examined acceleration (anterior and lateral directions) and gait barycentric factors (single-support phase and ratio of center of gravity maximum values) during gait and stair-stepping. Results Acceleration in the anterior direction in the sacral region was greater in healthy adults than in osteoarthritis (OA) patients during gait and stair-down. Acceleration in the anterior direction in the dorsal vertebral region was greater in OA patients than in healthy adults during (up and down) stair-stepping. Acceleration in the lateral direction in the sacral region was greater in healthy adults than in OA patients during stair-up. Acceleration in the lateral direction in the dorsal vertebral region was greater in OA patients than in healthy adults during stair-stepping. The single-support phase was close to 1 for gait and stair-stepping in healthy adults and OA patients. The single-support time was largely the same for gait and stair-stepping in healthy adults. On the other hand, the single-support time was longer for stair-stepping than for gait in OA patients. The ratio of the center of gravity maximum values was greater for the sacral region than for the dorsal vertebral region. There was a significant difference in the stair-stepping ratio of the center of gravity maximum values between healthy adults and OA patients for the sacral region. Conclusion We considered that knee OA influenced acceleration in the anterior and lateral direction in the dorsal vertebral and the ratio of the center of gravity maximum values on gait oscillation.

Background:Pigmented villonodular synovitis (PVNS) is a rare disorder around the ankle joint. The optimal treatment for diffuse-type PVNS is still controversial because of the high incidence of recurrence. We present the clinical features of our patients and review the current diagnostic and treatment modalities.Methods:Five patients with PVNS located around the ankle were surgically treated. In three patients, diffuse PVNS arose from the ankle joint, and in the other two it arose from the calcaneocuboid and intercuneiform joints. The average follow-up time after surgery was 2.9 years (range, 2–4.6 years).Results:The average time between onset of pain and diagnosis of PVNS was 6.4 years (range, 4–10 years). Arthrotomic tumor resection was performed in all of the patients. In the three patients with ankle joint PVNS, both medial and lateral approaches were used. One patient experienced mild infection at the surgical site, but this healed conservatively. No tumor recurrences had occurred after minimum follow-up of 2 years, although mild pain persisted in the three patients with ankle PVNS.Conclusions:Diagnosis of diffuse PVNS is frequently delayed due to vague symptoms and variable growth patterns. Orthopedic clinicians should be aware of the existence of this lesion, and it should be suspected in patients with persistent ankle swelling. To prevent tumor recurrence, accurate evaluation of tumor location and careful operative planning are mandatory. A combined surgical approach involving medial and lateral incision is necessary to expose the entire joint cavity.

Idiopathic avascular necrosis of the scaphoid, or Preiser disease, is a rare condition. Both the etiology and the pathology are still not well understood. We here present 2 cases with this disease and discuss the recommended treatment according to the stage of disease progression and by reference to previous studies in the literature. Similar to Kienböck disease, the recommended treatment should be selected according to the degree of disease progression. We believe that vascularized bone graft should be restricted to Herbert stage I or II cases with no evidence of radiocarpal arthritis or carpal instability. Our first case showed excellent revascularization following vascularized bone graft, as revealed by magnetic resonance image findings. The presence of arthrosis of the radiocarpal or mid-carpal joints is an indication for scaphoid excision with midcarpal fusion or proximal row carpectomy.

The origin of the peroneal intraneural ganglion and the outcome of treatment are still controversial. We report here three cases with peroneal intraneural ganglion and discuss the appropriate treatment. In our cases, 58-, 62-, and 65-year-old patients were operated on with extraneural decompression and epineurotomy within 4 months after onset of drop foot. Two cases demonstrated intraneural ganglion connecting to the articular branch and traversing to the deep and common peroneal nerve. At the 1-year follow-up, paralyzed peroneal nerve could be recovered in all patients even with residual ganglion. We propose correct early diagnosis, simple exoneural dissection, and atraumatic epineurotomy for the successful treatment of peroneal intraneural ganglion. Disruption of the stalk in the articular branch is a key point to prevent recurrence. For early diagnosis, clinicians should be aware of the existence of this rare lesion.

Background. Marked hyperplasia of the parathyroid gland (PTG) is a characteristic feature of severe hyperparathyroidism in patients under chronic haemodialysis treatment. Percutaneous ethanol injection therapy (PEIT) is now becoming popular in Japan as a treatment option for secondary hyperparathyroidism (SHPT) and its cost is covered by the National Health Insurance (NHI) System. The Japanese Society for Parathyroid Intervention surveyed its membership in 2004 to revise the guidelines for the use of PEIT. Methods. The project was approved by the Executive Committee of the Society, and the primary questionnaire was addressed to 3268 centres (departments) affiliated with the Japanese Society for Dialysis Therapy. A follow-up questionnaire was sent to all the centres that responded. Results. Although the number of centres to which the questionnaire was sent in 2004 was 3268, compared with 2653 in 1998, the number of responses decreased from 1425 (53.7%) in 1998 to 962 (29.4%) in 2004. To the question of whether the centre performed PEIT, 114 (11.9%) answered 'Yes' and 848 (88.1%) answered 'No' in 2004. It was an increase from 1998 when only 83 (5.8%) of 1425 centres answered 'Yes'. In the 1998 survey, 612 patients underwent PEIT at 74 centres, and in 2004, 2098 patients underwent PEIT at 111 centres. Conclusions. PEIT may become the frequently performed treatment for SHPT patients who become resistant to medical therapy. However, the same problems as in 1998 remain unsolved; that is, recurrent nerve paralysis, difficulty of post-PEIT PTx and lack of evidence showing the long-term effectiveness of PEIT.

STUDY DESIGN Determination of alar, transverse, and apical ligament strains during simulated head-turned rear impact. OBJECTIVES To quantify the alar, transverse, and apical ligament strains during head-turned rear impacts of increasing severity, to compare peak strains with baseline values, and to investigate injury mechanisms. SUMMARY OF BACKGROUND DATA Clinical and epidemiologic studies have documented upper cervical spine ligament injury due to severe whiplash trauma. There are no previous biomechanical studies investigating injury mechanisms during head-turned rear impacts. METHODS Whole cervical spine specimens (C0-T1) with surrogate head and muscle force replication were used to simulate head-turned rear impacts of 3.5, 5, 6.5, and 8 g horizontal accelerations of the T1 vertebra. The peak ligament strains during impact were compared (P < 0.05) to baseline values, obtained during a noninjurious 2 g acceleration. RESULTS The highest right and left alar ligament average peak strains were 41.1% and 40.8%, respectively. The highest transverse and apical ligament average strain peaks were 17% and 21.3%, respectively. There were no significant increases in the average peak ligament strains at any impact acceleration compared with baseline. CONCLUSIONS The alar, transverse, and apical ligaments are not at risk for injury due to head-turned rear impacts up to 8 g. The upper cervical spine symptomatology reported by whiplash patients may, therefore, be explained by other factors, including severe whiplash trauma in excess of 8 g peak acceleration and/or other impact types, e.g., offset, rollover, and multiple collisions.

Head-turned whole cervical spine model was stabilized with muscle force replication and subjected to simulated rear impacts of increasing severity. Multiplanar flexibility testing evaluated any resulting injury.To identify and quantify cervical spine soft tissue injury and injury threshold acceleration for head-turned rear impact, and to compare these data with previously published head-forward rear and frontal impact results.Epidemiologically and clinically, head-turned rear impact is associated with increased injury severity and symptom duration, as compared to forward facing. To our knowledge, no biomechanical data exist to explain this finding.Six human cervical spine specimens (C0-T1) with head-turned and muscle force replication were rear impacted at 3.5, 5, 6.5, and 8 g, and flexibility tests were performed before and after each impact. Soft tissue injury was defined as a significant increase (P0.05) in intervertebral flexibility above baseline. Injury threshold was the lowest T1 horizontal peak acceleration that caused the injury.The injury threshold acceleration was 5 g with injury occurring in extension or axial rotation at C3-C4 through C7-T1, excluding C6-C7. Following 8 g, 3-plane injury occurred in extension and axial rotation at C5-C6, while 2-plane injury occurred at C7-T1.Head-turned rear impact caused significantly greater injury at C0-C1 and C5-C6, as compared to head-forward rear and frontal impacts, and resulted in multiplanar injuries at C5-C6 and C7-T1.

Intervertebral Neck Injury Criterion (IV-NIC) is based on the hypothesis that dynamic three-dimensional intervertebral motion beyond physiological limits may cause multiplanar injury of cervical spine soft tissues. Goals of this study, using a biofidelic whole human cervical spine model with muscle force replication and surrogate head in simulated side impacts, were to correlate IV-NIC with multiplanar injury and determine IV-NIC injury threshold for each intervertebral level.Using a bench-top apparatus, side impacts were simulated at 3.5, 5, 6.5, and 8 g horizontal accelerations of the T1 vertebra. Pre- and post-impact flexibility testing in three-motion planes measured the soft tissue injury, i.e., significant increase (p0.05) in neutral zone (NZ) or range of motion (RoM) at any intervertebral level, above corresponding physiological limit.IV-NIC in left lateral bending correlated well with total lateral bending RoM (R = 0.61, P0.001) and NZ (R = 0.55, P0.001). Additionally, the same IV-NIC correlated well with left axial rotation RoM (R = 0.50, P0.001). IV-NIC injury thresholds (95% confidence limits) varied among intervertebral levels and ranged between 1.5 (0.6-2.4) at C3-C4 and 4.0 (2.4-5.7) at C7-T1. IV-NIC injury threshold times were attained beginning at 84.5 ms following impact.Present results suggest that IV-NIC is an effective tool for determining multiplanar soft tissue neck injuries by identifying the intervertebral level, mode, time, and severity of injury.

Automotive collision simulations have been performed using either incremental or single trauma. In single trauma, a single impact is performed, while in incremental trauma, a series of impacts of increasing severity are executed. Equivalency of incremental and single trauma for soft tissue injury severity due to the final impact has not been established. Thus, the purpose of the present study was to investigate whether incremental and single trauma produced similar cervical spine subfailure injury severity due to simulated frontal impacts.Porcine cervical spine specimens (C2-T1) of the incremental trauma group were subjected to five frontal impacts (2, 3.5, 5, 6.5, 8 g), while single trauma specimens were subjected to a single impact (8 g). Flexibility tests were performed on specimens while intact and following each impact. Intact and post 8 g flexibility parameters were compared within incremental and single trauma groups and between groups.No significant differences (P0.05) were found between incremental and single trauma groups when either intact or post 8 g flexibility parameters were compared. Significant increases in flexibility parameters from intact to post 8 g were observed in both groups, indicating soft tissue injury.Incremental and single trauma produced equivalent subfailure cervical spine injury in simulated impacts, for the experimental conditions studied. This study may facilitate greater use of the incremental trauma protocol in future experimental designs.

Summary Although the deltoid muscle has been assumed to be an essential shoulder muscle, the full extent of postoperative functions of the upper extremity following its complete resection due to sarcoma has not been thoroughly investigated. In this study, we review patients who underwent wide resection for sarcoma in the deltoid muscle, followed by functional reconstruction using pedicled latissimus dorsi (LD) muscle transfer. Four patients with sarcoma arising in the deltoid muscle were reviewed. Tumor resection with a wide surgical margin resulted in loss of the entire deltoid muscle together with the axillary nerve. For reconstruction, the ipsilateral pedicled LD muscle was transferred on its neurovascular pedicle for use as a functional substitute. One case had local recurrence and the transferred LD myocutaneous flap was resected. There were no serious complications after the operation, and all flaps survived perfectly. Wound healing at both the recipient and donor sites was uneventful. Active abduction of the shoulder joint was >160° in all patients. The muscle manual test of shoulder flexion was good to normal and abduction was fair to good. Musculoskeletal Tumor Society scores were excellent in all cases and the average score was 92% (range, 87–93%). Our results suggest that removal of the entire deltoid muscle resulted in a slight impairment of function. Pedicled LD musculocutaneous flaps are useful for covering the defect that results from resection of the deltoid muscle and they contribute additional function to the affected shoulder.

For tumors that are located beside the main peripheral nerve, combined wide resection of both the tumor and peripheral nerve is mandatory. We here present an interesting case with synovial sarcoma of the wrist. An 8 cm of ulnar nerve defect was reconstructed by vascularized, folded sural nerve graft with the peroneal flap, whereas an 8 cm of distal ulna was reconstructed using extracorporeally irradiated osteochondral autograft. Our case showed excellent nerve regeneration. Extracorporeal irradiated osteochondral graft was a good option for reconstruction of the distal ulna. This procedure should be indicated for the reconstruction of non-weight-bearing joints. These kinds of reconstruction have been addressed in only a few cases of oncological reconstruction.

Digital glomus tumour is a rare neoplasm. Surgical excision is the only known curative treatment but the best approach for subungual glomus tumours is still controversial. A total of 12 patients with subungual glomus tumour were reviewed. There were 11 female patients and one male patient, with a mean age of 48.6 years. Surgical procedures were performed using an operative microscope and tumours were excised using the lateral subperiosteal approach. In all, 10 patients were satisfied with the outcome from the lateral operative approach because they were able to use the affected hand for kitchen work shortly after the treatment. One case presented residual tumour and underwent re-operation. No tumour recurrences and nail deformity were detected after excision with the lateral approach. The lateral subperiosteal approach was safe and reliable for the subungual glomus tumour and allowed full access to any glomus tumours. Microscopy allows careful visualisation of the tumour. It is important that surgeons accurately locate tumours to achieve complete excision.

We report here the unique case of 60-year-old man with severe ulnar nerve palsy caused by synovial chondromatosis arising from the pisotriquetral joint. At operation, the tumor entrapped the ulnar nerve proximal to the Guyon canal so that it was severely paralyzed. The ulnar neurovascular bundle could be separated safely under the microscope. To our knowledge, this type of severe neuropathy has not been reported before. Although synovial chondromatosis associated with peripheral nerve neuropathy is extremely rare, we should be aware of the existence of this type of compression neuropathy in the upper limb.

BACKGROUND: Side impact may cause neck and upper extremity pain, paresthesias, and impaired neck motion. No studies have quantified the cervical spine mechanical instability and injury threshold acceleration due to side impact. The goals of the present study were to identify and quantify cervical spine soft tissue injury and the injury threshold acceleration for side impact, and to compare these results with previous findings. METHODS: Six human cervical spine specimens (C0-T1) underwent 3.5, 5, 6.5, and 8 g impacts. Pre- and postimpact flexibility tests were performed. Soft tissue injury was defined as a significant increase (p < 0.05) in the average intervertebral flexibility above the baseline 2 g impact. The injury threshold was the lowest T1 horizontal peak acceleration that caused the injury. RESULTS: The injury threshold acceleration was 6.5 g, with injuries occurring at C4-C5 through C7-T1 in flexion, axial rotation, or left lateral bending. After 8 g, three-plane injury was observed at C4-C5 and C6-C7, whereas two-plane injury occurred at C3-C4 in flexion and left lateral bending and at C5-C6 and C7-T1 in axial rotation and left lateral bending. CONCLUSIONS: Side impact caused multiplanar injuries at C3-C4 through C7-T1 and significantly greater injury at C6-C7, as compared with head-forward rear impact. Language: en

STUDY DESIGN An in vitro biomechanical study. OBJECTIVES The objectives were to: quantify dynamic canal pinch diameter (CPD) narrowing during simulated bilateral facet dislocation of a cervical functional spinal unit model with muscle force replication, determine if peak dynamic CPD narrowing exceeded that observed post-trauma, and evaluate dynamic cord compression. SUMMARY OF BACKGROUND DATA Previous biomechanical models are limited to quasi-static loading or manual ligament transection. No studies have comprehensively analyzed dynamic CPD narrowing during simulated dislocation. METHODS Bilateral facet dislocation was simulated using 10 cervical functional spinal units (C3-C4: n = 4; C5-C6: n = 3; C7-T1: n = 3) with muscle force replication by frontal impact of the lower vertebra. Rigid body transformation of kinematic data recorded optically was used to compute the CPD in neutral posture (before dislocation), during dynamic impact (peak during dislocation), and post-impact (flexion rotation = 0(0) degrees ). Peak dynamic impact and post-impact CPD narrowing were statistically compared. RESULTS Average peak dynamic impact CPD narrowing significantly exceeded (P < 0.05) post-impact narrowing and occurred as early as 71.0 ms following impact. The greatest dynamic impact narrowing of 7.2 mm was observed at C3-C4, followed by 6.4 mm at C5-C6, and 5.1 mm at C7-T1, with average occurrence times ranging between 71.0 ms at C7-T1 and 97.0 ms at C5-C6. CONCLUSION Extrapolation of the present results indicated dynamic spinal cord compression of up to 88% in those with stenotic canals and 35% in those with normal canal diameters. These results are consistent with the wide range of neurologic injury severity observed clinically due to bilateral facet dislocation.

Previous clinical studies have identified the cervical facet joint, including the capsular ligaments, as sources of pain in whiplash patients. The goal of this study was to determine whether whiplash caused increased capsular ligament laxity by applying quasi-static loading to whiplash-exposed and control capsular ligaments.A total of 66 capsular ligament specimens (C2/3 to C7/T1) were prepared from 12 cervical spines (6 whiplash-exposed and 6 control). The whiplash-exposed spines had been previously rear impacted at a maximum peak T1 horizontal acceleration of 8 g. Capsular ligaments were elongated at 1mm/s in increments of 0.05 mm until a tensile force of 5 N was achieved and subsequently returned to neutral position. Four pre-conditioning cycles were performed and data from the load phase of the fifth cycle were used for subsequent analyses. Ligament elongation was computed at tensile forces of 0, 0.25, 0.5, 0.75, 1.0, 2.5, and 5.0 N. Two factor, non-repeated measures ANOVA (P0.05) was performed to determine significant differences in the average ligament elongation at tensile forces of 0 and 5 N between the whiplash-exposed and control groups and between spinal levels.Average elongation of the whiplash-exposed capsular ligaments was significantly greater than that of the control ligaments at tensile forces of 0 and 5 N. No significant differences between spinal levels were observed.Capsular ligament injuries, in the form of increased laxity, may be one component perpetuating chronic pain and clinical instability in whiplash patients.

Intervertebral Neck Injury Criterion (IV-NIC) hypothesizes that dynamic three-dimensional intervertebral motion beyond physiological limit may cause multiplanar soft-tissue injury. Present goals, using biofidelic whole human cervical spine model with muscle force replication and surrogate head in head-turned rear impacts, were to: (1) correlate IV-NIC with multiplanar injury, (2) determine IV-NIC injury threshold at each intervertebral level, and (3) determine time and mode of dynamic intervertebral motion that caused injury.Impacts were simulated at 3.5, 5, 6.5, and 8 g horizontal accelerations of T1 vertebra (n = 6; average age: 80.2 years; four male, two female donors). IV-NIC was defined at each intervertebral level and in each motion plane as dynamic intervertebral rotation divided by physiological limit. Three-plane pre- and post-impact flexibility testing measured soft-tissue injury; that is significant increase in neutral zone (NZ) or range of motion (RoM) at any intervertebral level, above baseline. IV-NIC injury threshold was average IV-NIC peak at injury onset.IV-NIC extension peaks correlated best with multiplanar injuries (P0.001): extension RoM (R = 0.55) and NZ (R = 0.42), total axial rotation RoM (R = 0.42) and NZ (R = 0.41), and total lateral bending NZ (R = 0.39). IV-NIC injury thresholds ranged between 1.1 at C0-C1 and C3-C4 to 2.9 at C7-T1. IV-NIC injury threshold times were attained between 83.4 and 150.1 ms following impact.Correlation between IV-NIC and multiplanar injuries demonstrated that three-plane intervertebral instability was primarily caused by dynamic extension beyond the physiological limit during head-turned rear impacts.

Object A rotated head posture at the time of vehicular rear impact has been correlated with a higher incidence and greater severity of chronic radicular symptoms than accidents occurring with the occupant facing forward. No studies have been conducted to quantify the dynamic changes in foramen dimensions during head-turned rear-impact collisions. The objectives of this study were to quantify the changes in foraminal width, height, and area during head-turned rear-impact collisions and to determine if dynamic narrowing causes potential cervical nerve root or ganglion impingement. Methods The authors subjected a whole cervical spine model with muscle force replication and a surrogate head to simulated head-turned rear impacts of 3.5, 5, 6.5, and 8 G following a noninjurious 2-G baseline acceleration. Continuous dynamic foraminal width, height, and area narrowing were recorded, and peaks were determined during each impact; these data were then statistically compared with those obtained at baseline. The authors observed significant increases (p < 0.05) in mean peak foraminal width narrowing values greater than baseline values, of up to 1.8 mm in the left C5–6 foramen at 8 G. At the right C2–3 foramen, the mean peak dynamic foraminal height was significantly narrower than baseline when subjected to rear-impacts of 5 and 6.5 G, but no significant increases in foraminal area were observed. Analysis of the results indicated that the greatest potential for cervical ganglion compression injury existed at C5–6 and C6–7. Greater potential for ganglion compression injury existed at C3–4 and C4–5 during head-turned rear impact than during head-forward rear impact. Conclusions Extrapolation of present results indicated potential ganglion compression in patients with a non-stenotic foramen at C5–6 and C6–7; in patients with a stenotic foramen the injury risk greatly increases and spreads to include the C3–4 through C6–7 as well as C4–5 through C6–7 nerve roots.

Background Previous clinical studies have documented successful neck pain relief in whiplash patients using nerve block and radiofrequency ablation of facet joint afferents, including capsular ligament nerves. No previous study has documented injuries to the neck ligaments as determined by altered dynamic mechanical properties due to whiplash. The goal of the present study was to determine the dynamic mechanical properties of whiplash-exposed human cervical spine ligaments. Additionally, the present data were compared to previously reported control data. The ligaments included the anterior and posterior longitudinal, capsular, and interspinous and supraspinous ligaments, middle-third disc, and ligamentum flavum. Methods A total of 98 bone-ligament-bone specimens (C2–C3 to C7-T1) were prepared from six cervical spines following 3.5, 5, 6.5, and 8 g rear impacts and pre- and post-impact flexibility testing. The specimens were elongated to failure at a peak rate of 725 (SD 95) mm/s. Failure force, elongation, and energy absorbed, as well as stiffness were determined. The mechanical properties were statistically compared among ligaments, and to the control data (significance level: P < 0.05; trend: P < 0.1). The average physiological ligament elongation was determined using a mathematical model. Results For all whiplash-exposed ligaments, the average failure elongation exceeded the average physiological elongation. The highest average failure force of 204.6 N was observed in the ligamentum flavum, significantly greater than in middle-third disc and interspinous and supraspinous ligaments. The highest average failure elongation of 4.9 mm was observed in the interspinous and supraspinous ligaments, significantly greater than in the anterior longitudinal ligament, middle-third disc, and ligamentum flavum. The average energy absorbed ranged from 0.04 J by the middle-third disc to 0.44 J by the capsular ligament. The ligamentum flavum was the stiffest ligament, while the interspinous and supraspinous ligaments were most flexible. The whiplash-exposed ligaments had significantly lower (P = 0.036) failure force, 149.4 vs. 186.0 N, and a trend (P = 0.078) towards less energy absorption capacity, 308.6 vs. 397.0 J, as compared to the control data. Conclusion The present decreases in neck ligament strength due to whiplash provide support for the ligament-injury hypothesis of whiplash syndrome.

Between 23 and 70% of occupants involved in frontal impacts sustain cervical spine injuries, many with neurological involvement. It has been hypothesized that cervical spinal cord compression and injury may explain the variable neurological profile described by frontal impact victims. The goals of the present study, using a biofidelic whole cervical spine model with muscle force replication, were to quantify canal pinch diameter (CPD) narrowing during frontal impact and to evaluate the potential for cord compression. The biofidelic model and a sled apparatus were used to simulate frontal impacts at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. The CPD was measured in the intact specimen in the neutral posture (neutral posture CPD), under static sagittal pure moments of 1.5 Nm (pre-impact CPD), during dynamic frontal impact (dynamic impact CPD), and again under static pure moments following each impact (post-impact CPD). Frontal impact caused significant (P

The Intervertebral Neck Injury Criterion (IV-NIC) is based on the hypothesis that dynamic intervertebral motion beyond physiological limits may injure soft tissues. In contrast, the Neck Injury Criterion (NIC) hypothesizes that sudden change in spinal fluid pressure may cause neural injuries. The goals of this study, using the biofidelic whole human cervical spine model with muscle force replication, were to determine the IV-NIC injury threshold due to frontal impact at each intervertebral level, and to compare the IV-NIC and NIC in determining injury.Using a bench-top apparatus, frontal impacts were simulated at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. Pre- and post-trauma flexibility testing measured the soft tissue injury; that is, a significant increase (p0.05) in neutral zone or range of motion at any intervertebral level, above the corresponding physiological limit.Results indicated that the soft tissue injury occurred due to flexion mode of injury and its threshold was 8 g. The average IV-NIC injury threshold (95% confidence interval) was 2.0 (1.2-2.8) at C4-C5 and 2.3 (1.6-3.0) at C6-C7, while the average NIC injury threshold was 18.4 (17.9-19.0) m(2)/s(2). The NIC injury threshold was reached significantly earlier than all the IV-NIC injury thresholds, demonstrating that the NIC may be unable to predict facet and soft tissue injury caused by non-physiologic inververtebral rotation.Present results suggest that IV-NIC is an effective tool for determining soft tissue neck injuries by identifying the intervertebral level, mode, time, and severity of injury.

Cervical disc injury due to frontal impact has been observed in both clinical and biomechanical investigations; however, there is a lack of data that elucidate the mechanisms of disc injury during these collisions. The goals of the current study were to determine the peak dynamic disc annular tissue strain and disc shear strain during simulated frontal impact of the whole human cervical spine model with muscle force replication at 4 g, 6 g, 8 g and 10 g horizontal accelerations of the T1 vertebra. These data were compared with those obtained during physiological loading, and with previously reported rear impact data. Peak disc shear strain and peak annular tissue strain during frontal impact exceeded (p

SUMMARY 1. The effect of ibudilast, a drug that has been clinically used for asthma and the improvement of cerebrovascular disorders, was examined on glutamate neurotoxicity in cultured neurons from rat hippocampus. 2. The extent of neuronal damage induced by exposure of the neurons to glutamate for 5 min was estimated by the activity of lactate dehydrogenase (LDH) released from degenerated neurons into the medium during a 24 h postexposure period. When ibudilast was added into all pre-incubation, exposure and postexposure media, the extent of neuronal damage decreased to approximately half that of control at an ibudilast concentration of 43 μmol/L. 3. The neuroprotective effects of ibudilast were dose-dependent. Sufficient protection was detected even when ibudilast was added only into the postexposure medium. 4. The extent of 45Ca2+ influx during glutamate exposure was slightly reduced by the addition of ibudilast. Intracellular cAMP, as measured by radioimmunoassay, was increased by neuronal exposure to glutamate and then decreased after the removal of glutamate; however in the presence of ibudilast, AMP was maintained at the high level. 5. These results suggest that protection against glutamate neurotoxicity by ibudilast is not only attributable to the inhibition of phenomena that occur during glutamate exposure, such as Ca2+ influx, but also to some beneficial metabolic changes that are induced by a sustained high level of intracellular cAMP.