Severe hand contracture treated by external fixation after proximal row carpectomy and awake tenolysis after general anesthesia: A case report.

Wide-awake local anesthesia has many advantages. We describe a new method to use wide-awake local anesthesia with more flexibility. A 32-year-old man with a severe right-hand contracture after an iatrogenic tourniquet accident during an anterolateral thigh flap for a partial hand amputation underwent contracture release using external fixation after proximal row carpectomy and subsequent tenolysis. We performed most of the tenolysis procedure under general anesthesia and the final stage with an intraoperative assessment of active finger movement and dissection under local anesthesia. He regained his grip strength 2.5 years post-injury. General anesthesia is useful to treat a surgical site with extensive hard scars, whereas local anesthesia is useful for adjusting tension in an awake patient. The indication for wide-awake surgery is yet to be established; our method of combining general and local anesthesia in the tenolysis procedure illustrates the possibilities in expanding this method.

A Three-Step Method for the Treatment of Radioulnar Synostosis with Posterior Radial Head Dislocation.

Congenital radioulnar synostosis with posterior dislocation of the radial head remains challenging to treat. We describe a three-step treatment method that combines radial shaft osteotomy with a custom-made device, ulnar shaft osteotomy, and local adipofascial flap elevation procedures. For posterior radial head dislocation treatment, osteotomy near the proximal radius cannot recover physiological rotation of the radial head. Thus, we chose a precise radial shaft osteotomy with a custom-made device according to preoperative planning based on three-dimensional evaluation of the bone deformation. Performing radial shaft osteotomy alone, however, may not be enough to achieve sufficient supination range of motion. We, therefore, also performed ulnar shaft osteotomy. Finally, we elevated the local adipofascial flap to prevent re-adhesion. In three patients, the range of motion of the elbow improved postoperatively. In conclusion, our three-step method does not require a microsurgical technique and is easy to perform.

Do Not Cut Wood with an Angle Grinder, or You Might Lose a Finger: A Retrospective Study.

Background: Angle grinders are a handheld power tool used for grinding and polishing stone, metal, and concrete. Some people, however, use them with a circular saw blade attachment for cutting wood and consequently, suffer injuries. We aimed to investigate the underlying cause and mechanisms of injuries caused by cutting wood with an angle grinder. Methods: We conducted a retrospective study using medical records from our trauma center and identified 15 patients treated for angle grinder injury between 2017 and 2018. Moreover, we contacted the National Consumer Affairs Center of Japan for further information about angle grinder injuries. Results: Nine of the 15 patients used angle grinders improperly, of which only three patients were aware of the risk of injury. The details of the nine patients were as follows: the types of injuries: complete finger amputation (n = 2), partial finger amputation (n = 1), tendon injury with phalangeal fracture (n = 5), and tendon injury alone, (n = 1); the causes of accidents: kickback (n = 7) and glove entanglement (n = 2); and the accident situations: on-the-job (n = 5) and do-it-yourself (n = 4). Conclusions: The primary cause of angle grinder injury caused by cutting wood was a lack of user knowledge that an angle grinder cannot be used as a cutting tool. Appropriate feedback from hand surgeons are necessary to urge manufacturers to take safety measures.

Cervical Lordosis Ratio as a Novel Predictor for the Loss of Cervical Lordosis After Laminoplasty.

OBJECTIVE: Maintaining cervical lordosis (CL) after laminoplasty is important for indirect decompression of the spinal cord. This study aimed to identify preoperative dynamic radiographic predictors for the loss of CL after laminoplasty. METHODS: We retrospectively analyzed 141 consecutive patients who underwent cervical laminoplasty for cervical myelopathy. The following radiographic parameters were measured before surgery and at 1 year of follow-up: CL, C7 slope, C2-7 sagittal vertical axis (SVA), C2-7 range of motion (ROM), CL in flexion, CL in extension, ROM of flexion (Flex ROM), and ROM of extension. The CL ratio (CLR) was defined as 100 × Flex ROM/ C2-7 ROM. ΔCL was defined as postoperative CL minus preoperative CL. Patients were classified into 2 groups: group K (kyphotic change group, ΔCL ≤ -10) and group C (control group, ΔCL > -10). RESULTS: The patient population comprised 94 men and 47 women (mean age, 70.9 ± 9.4 years), with 24 patients (17.0%) classified into group K. CL, C7 slope, and CLR were significantly higher in group K than in group C. The groups did not significantly differ in age, sex, C2-7 SVA, and C2-7 ROM. On multivariable analysis, the CLR was significantly associated with postoperative kyphotic changes. On receiver-operating characteristic curve analysis (area under the curve = 0.717, p < 0.001), the cutoff value for CLR was 68.9%, with sensitivity and specificity of 87.5% and 57.3%, respectively. CONCLUSION: The CLR, reflecting the balance between flexion and extension mobility, was identified as a novel predictor for CL loss after laminoplasty, with a cutoff value of 68.9%.

Sequential chimeric free deep circumflex iliac artery bone flap and superficial circumflex iliac artery perforator flap from the same site for one-stage reconstructions of severe hand injury: A report of two cases.

Two flaps, namely the free vascularized iliac bone graft supplied by the deep circumflex iliac artery (DCIA) and the superficial circumflex iliac artery perforator flap supplied by the superficial circumflex iliac artery (SCIA), can be individually harvested from a single surgical field. We report two cases treated by these free flaps for severe hand injury with large skin defect and osteomyelitis. Sequential chimeric flaps were anastomosed between the ascending branch of the DCIA and the SCIA. The advantage of this method is more freedom in the flap insetting for complex tissue defects. For this reason, this method is also excellent for cosmetic appearance. Furthermore, donor site morbidity can be minimized because the flaps are harvested from the same site.

How Long Should We Immobilize the Wrist after Vascularized Bone Grafting for the Treatment of Scaphoid Nonunion?

Background: Although vascularized bone grafting can effectively treat scaphoid nonunion, the optimal duration of the immobilization period after bone grafting is unclear. Therefore, we aimed to examine the difference in the union rate and range of motion between short and long immobilization periods and infer the optimal post-immobilization period after pedicled vascularized bone grafting for scaphoid nonunion treatment. Methods: A total of 23 wrists (21 men and 1 woman) with scaphoid nonunion treated using an intercompartmental supraretinacular artery pedicled vascularized bone graft were analyzed. We examined the difference in the union rate and range of motion between patients immobilized for less than 49 days (short immobilization group) and those immobilized for more than 49 days (long immobilization group). The range of motion of the wrist joint was measured before and after surgery. Patient outcomes were also assessed. Results: The overall union rate was 95.6%. A significant difference was found in postoperative extension and flexion between the two groups, but not in terms of the functional outcome. If the intraoperative fixation is solid, intraoperative proximal pole bleeding is confirmed, and the follow-up radiograph shows a normal healing process, we propose immobilization of the wrist for ≤ 7 weeks. Conclusions: The immobilization duration should depend on the solidity of intraoperative fixation and a satisfactory appearance on follow-up radiography: absence of a gap at the graft interface, surrounding lucency, or movement of the implant and displacement of the graft. If there are no signs of graft failure and fixation is solid, immobilization of the wrist for 7 weeks or less is recommended.

Examination of the Dorsal Finger Vein Anatomy Using a Vein Visualization Device.

Background: The vein anatomy of the dorsal finger is often difficult to identify suitable veins for anastomosis when treating digital amputations, but it has not been well studied to date. The aim of our study was to determine the vein anatomy of the dorsal finger using a vein visualization device. Methods: The study sample consisted of 20 volunteers (11 men and 9 women; 148 fingers and 37 thumbs). The number and location of veins, the distance from the finger midline to the most central vein, and the distance from the central vein to the adjacent vein were examined using a vein visualization device, Stat Vein®, at the eponychial level, distal interphalangeal (DIP) joints, and proximal interphalangeal joints. Results: In the finger, the distance from the nail lunula edge to the vein at the eponychial level was about 5 mm and that from the central vein to the adjacent vein at the DIP joints was about 8 mm. In the thumb, the distance from the nail lunula margin to the vein at the eponychial level was about 5 mm and that from the central vein to the adjacent vein at the interphalangeal joints was about 6 mm. Conclusions: Treatment of DIP joint-level finger amputation requires identification of the central vein at first and then the site about 8 mm away from the central vein. In the treatment of eponychial-level finger amputation, the vein is found about 5 mm away from the nail lunula edge.

Reconstructing the Epicondyle and Collateral Ligament in Missing Condylar Region Associated with Severe Elbow Trauma: A Report of 2 Cases.

CASES: We report 2 cases of missing condylar region associated with severe elbow trauma treated with our new surgical technique and present the outcomes at the 9- and 10-year follow-ups. Our method focused on anatomical isometric point reconstruction, which consisted of the reconstruction of the missing condylar region with the iliac bone and the collateral ligament with the palmaris longus tendon. CONCLUSIONS: This injury is rare, and treatment is challenging because of the difficulty in identifying the isometric point. Both patients achieved good elbow function. The bone defect region was almost remodeled with minimal bone tunnel enlargement. Overall, our technique can provide positive results.

Correction of Humpback Deformities in Patients With Scaphoid Nonunion Using 1,2-Intercompartmental Supraretinacular Artery Pedicled Vascularized Bone Grafting With a Dorsoradial Approach.

PURPOSE: Although 1,2-intercompartmental supraretinacular artery (1,2-ICSRA)-based vascularized bone grafting (VBG) has gained popularity in the treatment of scaphoid nonunion, correcting humpback deformities with this technique remains challenging. The purpose of this retrospective study was to determine the possibility of correcting humpback deformities using a 1,2-ICSRA VBG with a dorsoradial approach. METHODS: We treated 25 patients with scaphoid nonunion using a 1,2-ICSRA VBG between January 2007 and December 2017. For those with a humpback deformity, we performed vascularized wedge grafting from the dorsoradial side, instead of inlay bone grafting from the dorsal or volar side of the scaphoid. After excluding patients with scaphoid nonunion without a humpback deformity and those followed up for less than 6 months, we reviewed the imaging results and union rate in the remaining 19 patients (18 men and 1 woman). The nonunion sites and patient distribution were as follows: proximal one-third, 2; waist, 16; and distal one-third, 1. RESULTS: The union rate at the last follow-up performed a minimum of 6 months after the intervention was 94.7%. The correction was adequate in 17 patients and inadequate in 2 patients. The lateral intrascaphoid, radiolunate, and scapholunate angles were improved. CONCLUSIONS: Humpback and dorsal intercalated segmental instability deformities can be corrected adequately using a 1,2-ICSRA VBG with a dorsoradial approach. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Lumbar Spinal Surgery in Patients With Parkinson Disease: A Multicenter Retrospective Study.

STUDY DESIGN: A multicenter, retrospective study. OBJECTIVE: To identify the factors that affect surgery-related complications and to clarify the surgical strategy for treating lumbar disorders in Parkinson disease (PD). SUMMARY OF BACKGROUND DATA: Previous studies have reported a high complication rate for spinal surgery in patients with PD. Because of the limited number of studies, there are no guidelines for spinal surgery for PD patients. METHODS: We retrospectively reviewed the records for 67 PD patients who underwent lumbar spinal surgery. The patients were divided into 3 groups: 12 patients underwent laminectomy (Laminectomy), 24 underwent fusion surgery (Fusion) for lumbar canal stenosis, and 31 underwent corrective surgery for spinal deformity (Deformity). We assessed surgery-related complications in each group. The Cox proportional hazards model was used to identify the factors that predicted surgical failure. RESULTS: The percentages of patients who experienced failure of the initial surgery were 33.3% in the Laminectomy group, 45.8% in the Fusion group, and 67.7% in the Deformity group. The rates of implant failure were high in the Fusion and Deformity groups (33.3% and 38.7%, respectively). The Deformity group had a high rate of postoperative fracture (41.9%). These complications occurred at the most caudal site within a year after surgery and resulted in progression of kyphotic deformity. Multivariate analysis revealed that preoperative lumbar lordosis angle (LL) (per -1 degree) was associated with a failure of the initial surgery (hazard ratio, 1.024; 95% confidence interval, 1.008-1.04; P=0.003). CONCLUSIONS: We have demonstrated that a small preoperative LL increases the risk for failure of the initial surgery. Attaining and maintaining the proper lumbar lordosis with rigid fixation may be necessary in PD patients with a small preoperative LL.

Surgical Treatment for Thoracic Myelopathy Due to Simultaneous Ossification of the Posterior Longitudinal Ligament and Ligamentum Flavum at the Same Level.

STUDY DESIGN: Retrospective review. OBJECTIVE: The aim of this study was to assess the clinical outcomes of surgery in patients with simultaneous ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) at the same thoracic spine level and identify the risk factors for poor outcomes. SUMMARY OF BACKGROUND DATA: OPLL complicated with OLF in the thoracic spine is a rare condition. The optimal treatment option for thoracic myelopathy due to OPLL and OLF remains controversial, and high risk of postoperative paralysis remains a major complication. METHODS: We conducted a retrospective review of clinical and radiographic records of 15 patients who underwent surgery for simultaneous OPLL and OLF at the same level. RESULTS: Simultaneous OPLL and OLF occurred in the upper thoracic spine in 3 patients (20%), mid-thoracic spine in 10 patients (67%), and lower thoracic spine in 2 patients (13%). Six, 4, 2, and 3 patients underwent posterior decompression, posterior decompression and fusion, posterior decompression and circumferential decompression through a posterior approach, and circumferential decompression and posterior fusion, respectively. The mean Japanese Orthopaedic Association score before surgery and at the final follow-up was 5.7±1.9 and 7.0±2.1 points, respectively, yielding a mean recovery rate of 16.5%. However, no significant difference was observed between preoperative and postoperative Japanese Orthopaedic Association scores. Two patients with mid-thoracic lesions reported postoperative lower extremity weakness. Mid-thoracic lesions and considerable blood loss were risk factors for poor surgical outcome. CONCLUSIONS: Simultaneous OPLL and OLF in the mid-thoracic spine was observed in two thirds of the patients. We suggest that simultaneous OPLL and OLF in this area has a relatively poor recovery and may be very challenging and risky to treat, regardless of the surgical method selected, and recommend early surgery for OPLL and OLF in the mid-thoracic spine.

[Hip Fracture--Epidemiology, Management and Liaison Service. Prevention of the secondary hip fractures utilizing the regional post-referral treatment plan].

Fragility fracture can result in a series of fractures, with the need for the prevention of secondary hip fractures seen as increasingly pertinent in Japan. In 2006, regional post-referral treatment plans for femoral neck fracture came into effect in Japan, but treatment of fracture and prevention of secondary fracture were fragmented. Patient education about prevention included on explanation forms were commenced, but the levels of discharge prescription for osteoporosis medications did not indicate an improvement. We evaluated a fracture liaison service for post-referral treatment plans for femoral neck fracture, by registering rehabilitation-stage hospitals and surveying data over a six-month period about whether there was prescription of osteoporosis medications on discharge, and the varieties of medication prescribed.

Investigation on 2331 cases of pulled elbow over the last 10 years.

Pulled elbow is a common upper extremity injury in children. We present a retrospective study of 2331 pulled elbow cases examined in our hospital over the last ten years. All pediatric patients with a diagnosis of pulled elbow from January 2002 to December 2011 were retrospectively reviewed according to sex, age, affected arm, recurrence rate, mechanism of injury and treatment outcomes. There is no significant sex difference. The frequency of injury peaked for both boys and girls at 6 months and 2 years of age. The left arm was more affected than the right. The recurrence rate was 14%. In about 50% of cases, the cause of injury was forcible traction to the forearm. Almost all of the splinted patients, caused by severe pain or lack of mobility of the affected limb following reduction, recovered within 2 weeks, but 2 were later diagnosed with a fracture. For infants less than 1 year old, injury can often occur when rolling over. For children 1 year old or older the left arm is more commonly affected, and the frequency of injuries to the left arm increases with age, possibly because the left hand is commonly held by the guardian's dominant right hand and faster development of muscle strength in the child's dominant right arm works toward preventing injury to that arm with age.

Radiographic risk factors and surgical outcomes for retroodontoid pseudotumors.

STUDY DESIGN: Retrospective review. OBJECTIVE: The aim of this study is to assess the radiographic characteristics of patients with a retroodontoid pseudotumor and to evaluate the efficacy of posterior fusion. SUMMARY OF BACKGROUND DATA: Retroodontoid pseudotumors are usually caused by chronic atlantoaxial instability in patients with rheumatoid arthritis (RA). However, the pathomechanism and optimum treatment are unknown. METHODS: We reviewed the charts and radiographs of 11 patients (5 RA and 6 non-RA) with a retroodontoid pseudotumor who underwent posterior fusion. Preoperative radiographs were evaluated for atlantodental interval; Redlund-Johnell criterion; O-C1, C1-2, C2-3, and C2-7 angles. The Japanese Orthopaedic Association (JOA) score was used to evaluate clinical outcomes. RESULTS: All RA patients and 1 non-RA patient displayed atlantoaxial subluxation. Three patients underwent occipitocervical fusion and 8 patients atlantoaxial fusion. The JOA score improved significantly from 10.0 to 12.8 at follow-up (P<0.01). The retroodontoid pseudotumor regressed in 10 patients. Maximal thickness of the pseudotumor decreased from 8.9 mm preoperatively to 5.3 mm (P<0.01) at follow-up. In non-RA patients, the mean differences (Δ) between flexion and extension were 7.8, 13.4, 3.5, and 18.5 degrees for ΔO-C1, ΔC1-2, ΔC2-3, and ΔC2-7, respectively. CONCLUSIONS: In RA patients, a retroodontoid pseudotumor may develop because of atlantoaxial subluxation. In non-RA patients, excessive atlantoaxial angular motion because of the limited range of motion of O-C1 and/or subaxial vertebra may cause a pseudotumor. Atlantoaxial fusion to suppress atlantoaxial instability is one of the optimum treatments.

Unilateral atlantal lateral mass hypertrophy associated with atlanto-occipital fusion.

PURPOSE: Unilateral hypertrophy of the lateral mass of the atlas is an extremely rare condition. The authors present a rare type of unilateral atlantal mass hypertrophy with atlanto-occipital fusion which is associated with an invaginated lateral mass of the atlas and the odontoid process into the foramen magnum. METHODS: A 45-year-old woman presented with a 2-year history of progressive bilateral weakness in the upper and lower extremities and gait disturbance. The left lateral mass of the atlas was hypertrophied and had invaginated into the foramen magnum with the odontoid. The spinal cord was severely compressed at the level of the foramen magnum, surrounded by the lateral mass of the atlas, the odontoid process and the occipital bone. RESULTS: First, ventral decompression was performed using a transmandibular approach. The anterior arch of the atlas, the medial side of the hypertrophied lateral mass and the odontoid process were resected. Two weeks after primary surgery, posterior occipitocervical fusion was performed. The postoperative course of the patient was uneventful. Three years after the operation, she could walk without assistance and her paresthesia improved. CONCLUSIONS: To our knowledge, such a case of unilateral atlantal mass hypertrophy associated with atlanto-occipital fusion has not been described previously. The authors discuss the pathology of this case and review the literature on unilateral atlantal mass hypertrophy and associated anomalies of the upper cervical spine.

Risk factors for acute cervical spinal cord injury associated with ossification of the posterior longitudinal ligament.

STUDY DESIGN: Retrospective review. OBJECTIVE: To identify risk factors for traumatic cervical spinal cord injury (SCI) associated with ossification of the posterior longitudinal ligament (OPLL) by comparing patients with SCI and those with cervical myelopathy (CM) associated with OPLL. SUMMARY OF BACKGROUND DATA: Although the prevalence of OPLL among patients with cervical SCI is high, little is published about the risk factors for SCI associated with OPLL. METHODS: We evaluated 3 groups of patients: 34 with SCI associated with OPLL, 32 with CM associated with OPLL, and 32 normal controls. Developmental canal diameter, spinal canal stenosis, type of OPLL, and presence of ossification of the anterior longitudinal ligament (OALL) were evaluated using 3-dimensional computed tomography. RESULTS: The mean age of the SCI group was 71.5 years, significantly more than that of the CM group (63.3 years). The SCI and CM groups had significantly smaller developmental canals than controls. Canal stenosis caused by OPLL was significantly more severe in the CM group than in the SCI group. There were no significant differences in sex distribution or the type of OPLL. Mixed or segmental types of OPLL were the main cause of SCI and CM. The SCI group showed a significantly higher incidence of OALL (56%) than the CM group (22%). Cervical SCI occurred at the edge of the OPLL or OALL in 20 patients (59%). If limited to mixed or continuous types of OPLL, 18 of the 19 patients (95%) sustained SCI at the edge of the OPLL or OALL. CONCLUSION: Risk factors for cervical SCI associated with OPLL were being elderly, having a mixed or segmental type of OPLL, and presence of OALL. Most instances of SCI occurred at edges of the OPLL or OALL. Severe spinal canal stenosis caused by OPLL was not an essential risk factor for developing SCI.

Cerebral infarction due to an embolism after cervical pedicle screw fixation.

STUDY DESIGN: Case report and clinical discussion. OBJECTIVE: We report a rare case of delayed onset of cerebral infarction caused by an embolism after cervical pedicle screw (CPS) fixation. SUMMARY OF BACKGROUND DATA: CPS has a risk of vertebral artery (VA) injury. CPSs sometimes breach the transverse foramen without rupture of the VA. Most breaches are not considered harmful. METHODS: We present a case in a 71-year-old man who underwent an operation for CPS fixation and laminoplasty for cervical spondylomyelopathy. He presented symptoms of hemiparesis 3 days after the operation. The left C4 pedicle screw was proven to breach the transverse foramen. An angiogram showed a thrombus cranial to the screw. RESULTS: The patient underwent anticoagulation therapy without removal of screw. After 2 weeks, the thrombus had disappeared. Subsequently, the pedicle screws were removed. At final follow-up, the patient complained of a grade 4/5 hemiparesis, facial nerve palsy, and hearing loss in his left ear. CONCLUSION: To our knowledge, this is the first case report of delayed onset of cerebral infarction caused by an embolism after CPS fixation. When a CPS perforates the transverse foramen, even if no apparent VA injury occurs during the operation, the surgeon must take care not to risk cerebral infarction because of an embolism.

Consistency of low bone density across bone sites in SAMP6 laboratory mice.

The development of bone densitometry has made it clear that there are discrepancies in bone density at various measurement sites in a given individual. This study examined the consistency of bone density measurements across various sites in a strain of laboratory mouse (senescence-accelerated mouse; SAM). A systemic evaluation of the bone density was performed by dual-energy X-ray absorptiometry (DXA) on SAMP6 (P6) mice, a strain with low peak bone density, as measured by microphotodensitometry of the femoral bones, whereas the SAMP2 (P2) and SAMR1 (R1) strains have high peak bone density. We modified Jilka's method to more comprehensively measure the whole body and additional regions of interest (ROIs; head, right foreleg, left foreleg, right hindleg, left hindleg, spine, and tail). The age-related changes in the total (whole-body) BMD showed a common pattern among the strains studied, and the peak value was seen at 4 months old. P6 showed the lowest peak BMD. A detailed comparison of the bone density between P6 and P2 at the age of 4 months revealed significantly lower regional BMD values for P6 in all seven ROIs. The strain difference in BMD could not be attributed to a difference in size. In conclusion, P6 mice showed low bone density not only in their femurs but also in the subregions and over their entire body. This strain can be potentially useful in the investigation of the genetic basis of senile osteoporosis.

Atlantoaxial transarticular screw fixation for a high-riding vertebral artery.

STUDY DESIGN: The feasibility of inserting a screw for the narrow isthmus with a high-riding vertebral artery was evaluated in patients subjected to posterior atlantoaxial transarticular screw fixation. OBJECTIVE: To demonstrate the feasibility of inserting bilateral screws and obtaining a stable atlantoaxial complex for patients with a high-riding vertebral artery. SUMMARY OF BACKGROUND DATA: Posterior atlantoaxial transarticular screw fixation entails the potential risk of vertebral artery injury, which may be lethal. The risk is much higher for the narrow isthmus caused by a high-riding vertebral artery, and many authors recommend that the procedure should be abandoned if the isthmus is too narrow. On the other hand, bilateral screw fixation is stronger than unilateral screw fixation. METHODS: For this study 27 consecutive patients who submitted to atlantoaxial transarticular screw fixation were evaluated before surgery for the position of the vertebral artery grooves using computed tomography (CT) reconstruction. Seven of the patients were defined as having a unilateral high-riding vertebral artery. For these patients, bilateral screw insertion through the most posterior and medial part of the isthmus was performed. RESULTS: No massive bleeding or major complications were encountered in any patients with a high-riding vertebral artery. Postoperative computed tomography reconstruction demonstrated that five of the screws cleared the vertebral artery groove successfully, and two slightly breached it. No screws penetrated into the vertebral artery groove. CONCLUSIONS: It is possible to insert a screw safely, even into the narrow isthmus with a high-riding vertebral artery, if the surgeon realizes where the screw should be inserted and has the requisite insertion technique. Bilateral screw fixation should provide a high fusion rate.

A congenic mouse and candidate gene at the Chromosome 13 locus regulating bone density.

Previously, we identified two significant quantitative trait loci (QTLs) specifying the peak relative bone mass (bone mass corrected for bone size) on chromosomes (Chrs) 11 and 13 by interval mapping in two mouse strains, SAMP2 and SAMP6. The latter strain is an established murine model of senile osteoporosis and exhibits a significantly lower peak relative bone mass than SAMP2 mice. We recently designated the Chr 13 locus as Pbd2 (Peak bone density 2) and constructed a congenic strain, P6.P2-Pbd2(b), which carried a single genomic interval from the Chr 13 of SAMP2 on a SAMP6-derived osteoporotic background. In this study, we have constructed a congenic strain, P2.P6-Pbd2(a), carrying a SAMP6-derived susceptible interval on a SAMP2-derived resistance background. This congenic strain had a lower bone density than the background strain, SAMP2, based on three measurement methods, each utilizing a different principle for evaluating bone density: MD, DXA, and pQCT. Next, a candidate gene approach was used to find polymorphisms of Bmp6 (bone morphogenetic protein 6). The CAG trinucleotide repeat numbers in exon 1 of this gene differ among SAM strains. We found an association of CAG repeat length with relative peak bone mass in mice.