Early history of scapular fractures.

The first to use the term Scapula was Vesalius (1514-1564) and thus it has remained ever since. Probably the oldest injured scapula, from 250 million years ago, was described by Chinese authors of a skeletal examination of a fossilised remains of a dinosaur Yangchuanosaurus hepingensis. In humans, the oldest known scapular fractures date back to the prehistoric and early historic times. In ancient times, a fracture of acromion was described in the treatises of Hippocrates. Early modern history of the treatment of scapular fractures is closely interlinked with the history of the French surgery. The first to point out the existence of these fractures were Petit, Du Verney and Desault in the 18th century. The first study devoted solely to scapular fractures was published by Traugott Karl August Vogt in 1799. Thomas Callaway published in 1849 an extensive dissertation on injuries to the shoulder girdle, in which he discussed a number of cases known at that time. The first radiograph of a scapular fracture was published by Petty in 1907. Mayo Robson (1884), Lambotte (1913) and Lane (1914) were pioneers in the surgical treatment of these fractures, followed in 1923 by the French surgeons Lenormat, Dujarrier and Basset. The first internal fixation of the glenoid fossa, including a radiograph, was published by Fischer in 1939.

History of operative treatment of forearm diaphyseal fractures.

Diaphyseal fractures of the forearm have accompanied humanity throughout its history. Nonsurgical techniques dominated the treatment for centuries, and complications including nonunion and malunion were common. The 19th century featured the recognition of distinct injury patterns. With the development of anesthesia and antisepsis, the operative treatment became widespread. In 1878, Heine described fixation of the diaphyseal nonunion of the distal ulna using an intramedullary ivory peg. Parkhill reported on the application of external fixation for forearm fractures in 1897-1898. Hansmann published the case of plate osteosynthesis of an acute fracture of the radius in 1886. In 1913, Schöne published the technique of closed intramedullary fixation of diaphyseal fractures of the forearm using a silver wire. During the first 2 decades of the 20th century, plate osteosynthesis quickly spread across Europe and North America owing to the influence of Lambotte and Lane. After the World War II, plate osteosynthesis became the surgical treatment of choice for forearm diaphyseal fractures.

Treatment of distal humerus fractures in adults: a historical perspective.

Nonsurgical treatment was the mainstay of management of distal humerus fractures for centuries and nonunions and malunions were common. The 19th century featured the recognition of distinct injury patterns. With advances in radiology, anesthesia, antisepsis, and hardware technology, surgical treatment is now generally preferred, yet loss of elbow joint mobility can still be a vexing problem.

Relationship between the alignment of the occipitoaxial and subaxial cervical spine in patients with congenital atlantoxial dislocations.

STUDY DESIGN: Prospective radiographic analysis. OBJECTIVE: This study aimed to characterize the relationship between the alignment of the occipitoaxial (OA) and the subaxial spine, establish normal parameters, and to determine the influence of upper cervical spine alignment on subaxial degenerative disc disease (DDD) and clinical outcomes in this population. SUMMARY OF BACKGROUND DATA: Previous studies reported that the alignments of the upper and lower cervical spine are closely interrelated in patients with atlantoaxial dislocations of a rheumatoid etiology. None have focused on congenital etiologies or included patients with OA kyphosis. The influence of the upper cervical alignment on subaxial (DDD) and outcomes is also unclear. METHODS: Fifty-eight patients with congenital AAD undergoing surgical reduction and fusion were included. C0-C2 and C2-C7 angles were measured and DDD was assessed using plain radiographs. The relationship between the alignment of the OA joint and the subaxial cervical spine was evaluated, as well as the relationships between the cervical alignment, outcomes, and cervical DDD. RESULTS: C0-2 improved from a mean of 1.59±17.3 degrees preoperatively to a mean of 15±9.8 degrees postoperatively (P<0.001). C2-7 changed from a mean of 25.55±19.6 degrees to a mean of 14.2±14.4 degrees postoperatively (P<0.001). The OA and subaxial alignment were negatively correlated in this population both before (r=-0.84; P<0.001) and after (r=-0.64; P<0.001) surgical treatment. There was an increased incidence of DDD postoperatively (P<0.01), which was positively correlated with the postoperative C0-2 angle (r=0.54; P<0.001), but negatively correlated with the postoperative C2-7 angle (r=-0.79; P<0.001). CONCLUSIONS: Changes in OA alignment before and after surgery are associated with changes in the subaxial spine. There is a high incidence of postoperative DDD in the subaxial spine that seems to be related to sagittal alignment after surgery.

The effect of the X-Stop implantation on intervertebral foramen, segmental spinal canal length and disc space in elderly patients with lumbar spinal stenosis.

OBJECTIVES: To evaluate the biomechanical effect of the X-Stop device on the intervertebral foramen (IVF) and segmental spinal canal length (SSCL), as well as the intervertebral disc space at the implanted and the adjacent segments in patients with lumbar spinal stenosis (LSS). MATERIALS AND METHODS: Eight elderly patients with LSS, scheduled for X-stop implantation, were CT or MRI scanned to construct 3D vertebral models (L2-S1). Before and after the surgery, each patient was also imaged using a dual-fluoroscopic image system during weight-bearing standing and maximum extension-flexion. The positions of the vertebrae were then determined using an established 2D-3D model matching method. RESULTS: The data revealed that the postoperative IVF area was significantly increased by 32.9% (or 32 mm2) (p<0.05) and the IVF width was increased by 24.4% (or 1.1 mm, p=0.06) during extension, but with minimal change in standing and flexion. The IVF heights were significantly (p<0.05) increased at standing by 1.2 mm and extension by 1.8 mm, but not at flexion. The SSCL were significantly (p<0.05) increased at extension by 1.2 mm, but not at standing and flexion. Anterior disc space of the implanted level was significantly decreased from 8.0 to 6.6 mm during standing. CONCLUSION: The X-Stop implantation efficiently enlarged the IVF area in the elderly patients with LSS at the operated level with little biomechanical effect immediately on the superior and inferior adjacent levels. However, it reduced the anterior disc space at the implanted level.

Biomechanical evaluation of the X-Stop device for surgical treatment of lumbar spinal stenosis.

STUDY DESIGN: Controlled experimental study. OBJECTIVE: To evaluate the kinematical effects of X-Stop device on the spinal process at the operated and the adjacent segments before and after X-Stop surgeries during various weight-bearing postures in elderly patients with lumbar spine stenosis. SUMMARY OF BACKGROUND DATA: The mechanism of interspinous process (ISP) devices is to directly distract the ISP of the implanted level to indirectly decompress the intervertebra foramen and spinal canal. Few studies have investigated the changes of ISP gap caused by X-Stop implantation using magnetic resonance imaging or radiography, but the effect of X-Stop surgery on the kinematics of spinous processes during functional activities is still unclear. METHODS: Eight patients were tested before and, on average, 7 months after surgical implantation of the X-Stop devices using a combined computed tomography/magnetic resonance imaging and dual fluoroscopic imaging system during weight-bearing standing, flexion-extension, left-right bending, and left-right twisting positions of the torso. The shortest distances of the ISPs at the operated and the adjacent levels were measured using iterative closest point method and was dissected into vertical (gap) and horizontal (lateral translation) components. RESULTS: At the operated levels, the shortest vertical ISP distances (gap) significantly (P<0.05) increased by 1.5 mm during standing, 1.2 mm during left twist, 1.3 mm during extension, and 1.1 mm during flexion, whereas they also increased yet not significantly (P>0.05) in right twist, left bend, and right bend after the X-Stop implantation. The lateral translations were not significantly affected. At both cephalad and caudad adjacent levels, the ISP distances (vertical and horizontal) were not significantly affected during all postures after X-Stop implantation. CONCLUSION: The findings of this study indicate that implantation of the X-Stop devices can effectively distract the ISP space at the diseased level without causing apparent kinematic changes at the adjacent segments during the studied postures.

In vivo length patterns of the medial collateral ligament during the stance phase of gait.

PURPOSE: The function of the medial collateral ligament (MCL) during gait has not been investigated. Our objective was to measure the kinematics of the medial collateral ligament during the stance phase of gait on a treadmill using a combined dual fluoroscopic imaging system (DFIS) and MRI technique. METHODS: Three-dimensional models of the knee were constructed using magnetic resonance images of 7 healthy human knees. The contours of insertion areas of the superficial MCL (sMCL) and deep MCL (dMCL) on the femur and tibia were constructed using the coronal plane MR images of each knee. Both the sMCL and the dMCL were separated into 3 portions: the anterior, mid, and posterior bundles. The relative elongation of the bundles was calculated using the bundle length at heel strike (or 0% of the stance phase) as a reference. RESULTS: The lengths of the anterior bundles were positively correlated with the knee flexion angle. The mid-bundles of the sMCL and dMCL were found to function similarly in trend with the anterior bundles during the stance phase of the gait and their lengths had weak correlations with the knee flexion angles. The elongations of the posterior bundles of sMCL and dMCL were peaked at mid-stance and terminal extension/pre-swing stance phase. The lengths of the posterior bundles were negatively correlated with the knee flexion during the stance phase. CONCLUSION: The data of this study demonstrated that the anterior and posterior bundles of the sMCL and dMCL have a reciprocal function during the stance phase of gait. This data provide insight into the function of the MCL and a normal reference for the study of physiology and pathology of the MCL. The data may be useful in designing reconstruction techniques to better reproduce the native biomechanical behavior of the MCL. LEVEL OF EVIDENCE: IV.

Complications associated with thoracic pedicle screws in spinal deformity.

Thoracic pedicle screws have superior anchoring strength compared with other available fixation techniques. However, these are not universally accepted in many developing countries because of the concerns regarding safety and complications. In addition, there is evidence that pedicle morphology is unique in Chinese patients. The goal of this study was to analyze the complications seen at our institution, while using thoracic pedicle screws for the treatment of thoracic deformity, and to determine the safety of our techniques for the treatment of thoracic deformity in a Chinese population. From 1998 to 2005, there were 208 thoracic deformity patients treated at our institution, 70 of whom were male and 138 were female. Their age ranged from 11 to 55 years (mean of 14.9 years). All of them underwent corrective deformity surgery using posterior pedicle screw systems and follow-up was available for at least 3 years. Etiologic diagnoses included adolescent idiopathic scoliosis in 119 patients, congenital kyphoscoliosis in 38, adult scoliosis in 37 and undetermined in 14. Screw positions were evaluated using intraoperative and postoperative radiographs and a CT scan was performed when a concern for screw malposition was present. All radiographic evaluations were carried out in a double-blinded fashion. A total of 1,123 thoracic pedicle screws were inserted (5.4 thoracic screws/patient). The deformity correction rate was 81, 65 and 62% for idiopathic, congenital and adult scoliosis patients, respectively. The overall complication rate was 16.5% at the final follow-up. Complication rates directly and indirectly related to pedicle screws were 7.2 and 9.3%, respectively. There were no significant screw-related neurologic or visceral complications that adversely affected long-term results. The complications seen with thoracic pedicle screws in a Chinese population were similar to other populations and could be utilized safely for the treatment of thoracic deformity in this population.

Application guidelines for dynamic knee joint analysis with a dual fluoroscopic imaging system.

The widespread availability of mobile digital fluoroscopic systems with dynamic imaging capabilities places this type of motion analysis within reach of many research groups. With the addition of the second fluoroscope though, and the incorporation of a treadmill to analyze gait, the fluoroscopic analysis technique, which was once a rather straightforward method, has become more complex. Therefore, the purpose of the present manuscript was to provide a comprehensive review of the various processes that are associated with the dynamic knee joint motion analysis, including patient selection, construction of three-dimensional knee models, fluoroscopic scanning, and matching.

In vivo range of motion of the lumbar spinous processes.

The study design included an in vivo laboratory study. The objective of the study is to quantify the kinematics of the lumbar spinous processes in asymptomatic patients during un-restricted functional body movements with physiological weight bearing. Limited data has been reported on the motion patterns of the posterior spine elements. This information is necessary for the evaluation of traumatic injuries and degenerative changes in the posterior elements, as well as for improving the surgical treatment of spinal diseases using posterior procedures. Eight asymptomatic subjects with an age ranging from 50 to 60 years underwent MRI scans of their lumbar segments in a supine position and 3D models of L2-5 were constructed. Next, each subject was asked to stand and was positioned in the following sequence: standing, 45 degrees flexion, maximal extension, maximal left and right twisting, while two orthogonal fluoroscopic images were taken simultaneously at each of the positions. The MRI models were matched to the osseous outlines of the images from the two orthogonal views to quantify the position of the vertebrae in 3D at each position. The data revealed that interspinous process (ISP) distance decreased from L2 to L3 to L4 to L5 when measured in the supine position; with significantly higher values at L2-3 and L3-4 compared with L4-5. These differences were not seen with weight-bearing conditions. During the maximal extension, the ISP distance at the L2-3 motion segment was significantly reduced, but no significant changes were detected at L3-4 and L4-5. During flexion the ISP distances were not significantly different than those measured in the MRI position at all segments. Going from the left to right twist positions, the L4-5 segment had greater amounts of ISP rotation, while all segments had similar ranges of translation in the transverse plane. The interspinous process distances were dependent on body posture and vertebral level.

Interobserver reliability and intraobserver reproducibility of powers ratio for assessment of atlanto-occipital junction: comparison of plain radiography and computed tomography.

Powers ratio, as assessed on plain radiographs or computed tomography (CT) images, appears to have clinical and prognostic value. To date, the validation of this assessment tool has been limited to a small number of observers at a single site. No study has examined the intraobserver reproducibility and interobserver reliability of the Powers ratio measurement on plain radiographs or CT images among a large cohort of spine surgeons. This type of validation is critical to allow for the broader use of the Powers ratio methodology in research studies and clinical applications. Plain radiographs and spiral CT images of the cervical spine of 32 patients were assessed, and the Powers ratio was determined by five spine surgeons. Each surgeon performed three readings, 7 months apart. In the first round of measurements, the observers used only the Powers' method of instruction. The second and third measurement sets were obtained after an interactive teaching session on the methodology. The order of the images was altered for the second and third set of measurements. The coefficient of variation (Cv) was calculated to determine the intraobserver repeatability and interobserver reliability for each imaging technique. A Bland-Altman plot was then used to assess the agreement between the two imaging techniques. For interobserver reliability, the mean Cv of the Powers ratio was 9.09 and 4.31% for plain radiographs and CT, respectively. The Cv mean value for intraobserver reproducibility averaged 4.95% (range 1.39-9.08) when CT scans were used and 14.17% (range 7.54-34.30) when plain radiographs were used. For intraobserver reproducibility, the lowest and highest Cv mean value of five raters was 1.39 and 9.08% using CT scans and 7.54 and 34.3% using plain radiographs. The Bland-Altman plot, demonstrated that the two methods were in close agreement on the -0.8 and 0.89% interval for limits of agreement (bias +/- 1.96sigma). The intraobserver reproducibility and interobserver reliability of Powers ratio measurement was acceptable (<5%) with CT scans but not with plain radiographs. However, despite the statistically inferior reliability and repeatability, the Bland-Altman plot analysis showed that given the -0.8 and 0.89% limits of agreement, the two methods may be used interchangeably in clinical practice.

The effect of anterior cruciate ligament reconstruction on kinematics of the knee with combined anterior cruciate ligament injury and subtotal medial meniscectomy: an in vitro robotic investigation.

PURPOSE: The aims of this study were to determine: (1) the kinematic effect of subtotal medial meniscectomy on the anterior cruciate ligament (ACL)-deficient knee and (2) the effect of ACL reconstruction on kinematics of the knee with combined ACL deficiency and subtotal medial meniscectomy under anterior tibial and simulated quadriceps loads. METHODS: Eight human cadaveric knees were sequentially tested using a robotic testing system under 4 conditions: intact, ACL deficiency, ACL deficiency with subtotal medial meniscectomy, and single-bundle ACL reconstruction using a bone-patellar tendon-bone graft. Knee kinematics were measured at 0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion under an anterior tibial load of 130 N and a quadriceps muscle load of 400 N. RESULTS: Subtotal medial meniscectomy in the ACL-deficient knee significantly increased anterior and lateral tibial translations under the anterior tibial and quadriceps loads (P < .05). These kinematic changes were larger at high flexion (>or=60 degrees) than at low flexion angles. ACL reconstruction in knees with ACL deficiency and subtotal medial meniscectomy significantly reduced the increased anterior tibial translation, but could not restore anterior translation to the intact level with differences ranging from 2.6 mm at 0 degrees to 5.5 mm at 30 degrees of flexion. ACL reconstruction did not significantly affect the medial-lateral translation and internal-external tibial rotation in the presence of subtotal meniscectomy. CONCLUSIONS: Subtotal medial meniscectomy in knees with ACL deficiency altered knee kinematics, especially at high flexion angles. ACL reconstruction significantly reduced the increased tibial translation in knees with combined ACL deficiency and subtotal medial meniscectomy, but could not restore the knee kinematics to the intact knee level. CLINICAL RELEVANCE: This study suggests that meniscus is an important secondary stabilizer against anterior and lateral tibial translations and should be preserved in the setting of ACL reconstruction for restoration of optimal knee kinematics and function.

Effect of post-traumatic tibiotalar osteoarthritis on kinematics of the ankle joint complex.

BACKGROUND: Knowledge of joint kinematics in the healthy and diseased joint may be useful if surgical techniques and joint replacement designs are to be improved. To date, little is known about the kinematics of the arthritic tibiotalar joint and its effect on the kinematics of the subtalar joint. MATERIALS AND METHODS: Kinematics of the ankle joint complex (AJC) were measured in six patients with unilateral post-traumatic tibiotalar osteoarthritis in simulated heel strike, midstance and toe off weight bearing positions using magnetic resonance and dual fluoroscopic imaging techniques. The kinematic data obtained was compared to a normal cohort from a previous study. RESULTS: From heel strike to midstance, the arthritic tibiotalar joint demonstrated 2.2 +/- 5.0 degrees of dorsiflexion while in the healthy controls the tibiotalar joint plantarflexed 9.1 +/- 5.3 degrees (p < 0.01). From midstance to toe off, the subtalar joint in the arthritic group dorsiflexed 3.3 +/- 4.1 degrees whereas in the control group the subtalar joint plantarflexed 8.5 +/- 2.9 degrees (p < 0.01). The subtalar joint in the arthritic group rotated externally 1.2 +/- 1.0 degrees and everted 3.3 +/- 6.1 degrees from midstance to toe off while in the control group 12.3 +/- 8.3 degrees of internal rotation and 10.7 +/- 3.8 degrees eversion (p < 0.01 and p < 0.01, respectively) was measured. CONCLUSION: The current study suggests that during the stance phase of gait, subtalar joint motion in the sagittal, coronal, and transverse rotational planes tends to occur in an opposite direction in subjects with tibiotalar osteoarthritis when compared to normal ankle controls. This effectively represents a breakdown in the normal motion coupling seen in healthy ankle joints. CLINICAL RELEVANCE: Knowledge of ankle kinematics of arthritic joints may be helpful when designing prostheses or in assessing the results of treatment interventions.

Functional comparison of total knee arthroplasty performed with and without a navigation system.

This study was undertaken to compare the clinical and radiological outcomes achieved using total knee arthroplasty (TKA) with and without a navigation system. This study included 43 TKAs performed with a navigation system and 42 TKAs without a navigation system with a minimum two-year follow-up. We compared clinical outcomes including range of motion, Hospital for Special Surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores at the final follow-up. For radiological comparisons, we evaluated radiological alignment on standing radiographs of knees. HSS and WOMAC scores showed significant improvements at final follow-ups in both groups, but showed no significant inter-group differences (p > 0.05). Similarly, no significant differences were observed in range of motion (p = 0.962). TKAs performed with navigation showed significantly better outcomes in terms of mechanical angle and prosthetic alignment outliers than TKAs performed without navigation. However, we could not find any differences in functional outcomes between TKAs performed with or without a navigation system.

Determination of real-time in-vivo cartilage contact deformation in the ankle joint.

The knowledge of real-time in-vivo cartilage deformation is important for understanding of cartilage function and biomechanical factors that may relate to cartilage degeneration. This study investigated cartilage contact area and peak contact compressive strain of four healthy human ankle joints as a function of time using a combined magnetic resonance (MR) and dual-orthogonal fluoroscopic imaging technique. Each ankle was subjected to a different constant loading (between 700 and 820 N). The cartilage contact deformation was obtained from the first second to 300 s after the load was applied. In all ankle joints studied in this paper, contact strains increased to 24-38% at first 20 s after loading. Beyond 20 s, the change of cartilage contact deformation was relatively small and varied in a rate close to zero beyond 50 s. These data indicated that the cartilage contact areas and contact strain could raise dramatically right after loading and reach a relatively stable condition within 1 min after constant loading. The history of cartilage deformation determined in this study may provide a real-time boundary condition for 3D finite element simulation of in vivo cartilage contact stress in the joint as a function of time.

Rate of Neurologic Injury Following Lateralizing Calcaneal Osteotomy Performed Through a Medial Approach.

BACKGROUND: Calcaneal osteotomies are commonly used to correct varus hindfoot alignment in patients with symptomatic cavovarus deformity. Translational, closing wedge, and Malerba-type osteotomies have been implicated in the development of tarsal tunnel syndrome and neurologic injury to branches of the tibial nerve. The authors hypothesized that there would be minimal clinically important injury to the tibial nerve by performing a translational calcaneal osteotomy from a medial approach. METHODS: All patients undergoing a cavovarus reconstruction by a single surgeon were identified. Patients were included if they underwent a lateralizing calcaneal osteotomy via medial approach. Demographics, operative reports, and clinic notes were reviewed to identify concomitant procedures performed, incidence of postoperative tarsal tunnel syndrome, complications, and preoperative and postoperative nerve examinations. Postoperative radiographs were reviewed for location of the osteotomy relative to the posterior tubercle. RESULTS: Twenty-four patients underwent lateralizing calcaneal osteotomy via a medial approach. Of the osteotomies, 83.3% (20/24) were in the middle third of the calcaneus, with a mean of 11.6-mm translation. No patients developed postoperative tarsal tunnel syndrome or tibial nerve palsy. CONCLUSION: Lateralizing calcaneal osteotomy performed via a medial approach had a clinically negligible incidence of neurologic injury. Adequate translation was achieved to obtain correction of varus hindfoot deformity. The authors believe that there is less direct and less percussive injury to branches of the tibial nerve when performing the osteotomy from medial to lateral. This technique may represent an operative strategy to minimize risk to the tibial nerve and reduce neurologic deficit following cavovarus reconstruction. LEVEL OF EVIDENCE: Level IV, case series.

Association of perioperative blood transfusion and adverse events after operative treatment of proximal humerus fractures.

BACKGROUND: The purpose of this study was to assess the relationship between perioperative blood transfusion for proximal humerus fracture and inpatient mortality, adverse events, prolonged hospital stay, and nonroutine disposition. METHODS: Among the >55,000 patients with an operatively treated proximal humerus fracture identified in the Nationwide Inpatient Sample between 2008 and 2011, 17% received a perioperative blood transfusion. Multivariable logistic regression analyses addressed the association of blood transfusion with inpatient mortality, adverse events, hospital stay, and nonroutine discharge, accounting for comorbidities and other known confounders. RESULTS: Perioperative blood transfusion for fracture of the proximal humerus was not associated with inhospital death, but it was independently associated with inpatient adverse events (odds ratio (OR) 4.4, 95% confidence interval (CI) 4.2-4.6), prolonged hospital stay (OR 2.8, 95% CI 2.7-2.9), and increased nonroutine discharge (OR 1.8, 95% CI 1.7-1.9). CONCLUSIONS: Inpatients with fracture of the proximal humerus who receive transfusion are not more likely to die in hospital, but they do stay longer, experience more adverse events, and are less likely to be discharged home. Additional study is merited to determine if the judicious use of blood transfusion in the perioperative period can decrease inpatient morbidity and health-care resource utilisation. LEVEL OF EVIDENCE: Level II, Retrospective Design, Prognosis Study.

The reversibility of swan neck deformity in chronic atlantoaxial dislocations.

STUDY DESIGN: Prospective case series and radiographical analysis. OBJECTIVE: This study aimed to characterize the changes in subaxial alignment after surgical correction of occipitoaxial kyphosis, establish normal parameters, and report on clinical outcomes in a population of patients with chronic atlantoaxial dislocation patients presenting with swan neck deformities. SUMMARY OF BACKGROUND DATA: Swan neck deformity of the cervical spine is a term used to describe the simultaneous development of both abnormal kyphosis and hyperlordosis malalignments. Currently, there are no published series that discuss their outcomes after treatment and, more specifically, the subsequent changes that occur in the subaxial spine after the correction of the primary deformity in cases of chronic hyperkyphosis at the occipitoaxial segment. METHODS: This was a prospective clinical and radiographical study in a population of patients with chronic atlantoaxial dislocation presenting with swan neck deformities. C0-C2 and C2-C7 angles were measured using plain radiographs pre- and postsurgery. The relationship between the alignment of the occipitoaxial joint and the subaxial cervical spine was evaluated. Japanese Orthopaedic Society scores were used to assess functional outcomes. RESULTS: C0-C2 improved from a mean of -14.4° (SD, 9.5°) preoperatively to a mean of 7.8° (SD, 1.0°) postoperatively (P = 0.02). C2-C7 changed from a mean of 43° (SD, 2.8°) to a mean of 18.6° (SD, 11.2°) postoperatively (P = 0.02). A significant correlation was detected between the changes that occurred in the upper and lower cervical alignments (R = 0.133; P < 0.01). Clinically, the Japanese Orthopaedic Society preoperative scores improved significantly to postoperative (P < 0.01). CONCLUSION: This study reports the novel auto-correction of subaxial abnormalities after treatment of the primary upper cervical deformity and delineates the relationship between these 2 occurrences, thus demonstrating the reversibility of such complex abnormalities. Furthermore, the clinical outcomes after surgical treatment of swan neck deformities secondary to atlantoaxial dislocation are favorable and associated with a low complication rate.

Surgical treatment of low-grade isthmic spondylolisthesis with transsacral fibular strut grafts.

BACKGROUND: The ideal surgical treatment for adult low-grade isthmic spondylolisthesis (ALIS) remains unknown. Isolated anterior and posterior procedures are popular but have resulted in equivocal outcomes, whereas combined anterior and posterior procedures are associated with higher complication rates despite improved outcome. OBJECTIVE: To evaluate the clinical and radiographic outcomes following the treatment of ALIS using a 1-stage posterior approach with posterior decompression and posterolateral arthrodesis combined with an interbody fibular allograft strut. METHODS: Fifteen patients underwent fusion by a single surgeon using our modified technique. Seven patients were female and 8 were male, with a mean age of 48 years. All patients were classified as Meyerding grade II slips and underwent a posterior approach only, a decompressive laminectomy, and a circumferential fusion with the use of a transsacral fibular allograft and a posterolateral instrumented fusion. Postoperative clinical and radiographic evaluations were performed at 3, 6, and 12 months, and then on an annual basis. RESULTS: The average follow-up interval was 61 months. Three complications were seen: a single dural tear, an L5 radiculopathy secondary to a malpositioned pedicle screw, and one patient with urinary retention. The spines of all patients were determined to be fused by the 6-month postoperative visit. All patients returned to their normal activities of daily living. Significant improvements in the visual analog score were seen at all follow-up intervals. CONCLUSION: Transsacral interbody fibular allograft can be used successfully to supplement a posterolateral instrumented fusion in selected patients with low-grade ALIS.

Lumbar facet joint motion in patients with degenerative disc disease at affected and adjacent levels: an in vivo biomechanical study.

STUDY DESIGN: Controlled laboratory study. OBJECTIVE: To evaluate the effect of lumbar degenerative disc diseases (DDDs) on motion of the facet joints during functional weight-bearing activities. SUMMARY OF BACKGROUND DATA: It has been suggested that DDD adversely affects the biomechanical behavior of the facet joints. Altered facet joint motion, in turn, has been thought to associate with various types of lumbar spine pathology including facet degeneration, neural impingement, and DDD progression. However, to date, no data have been reported on the motion patterns of the lumbar facet joint in DDD patients. METHODS: Ten symptomatic patients of DDD at L4-S1 were studied. Each participant underwent magnetic resonance images to obtain three-dimensional models of the lumbar vertebrae (L2-S1) and dual fluoroscopic imaging during three characteristic trunk motions: left-right torsion, left-right bending, and flexion-extension. In vivo positions of the vertebrae were reproduced by matching the three-dimensional models of the vertebrae to their outlines on the fluoroscopic images. The kinematics of the facet joints and the ranges of motion (ROMs) were compared with a group of healthy participants reported in a previous study. RESULTS: In facet joints of the DDD patients, there was no predominant axis of rotation and no difference in ROMs was found between the different levels. During left-right torsion, the ROMs were similar between the DDD patients and the healthy participants. During left-right bending, the rotation around mediolateral axis at L4-L5, in the DDD patients, was significantly larger than that of the healthy participants. During flexion-extension, the rotations around anterioposterior axis at L4-L5 and around craniocaudal axis at the adjacent level (L3-L4), in the DDD patients, were also significantly larger, whereas the rotation around mediolateral axis at both L2-L3 and L3-L4 levels in the DDD patients were significantly smaller than those of the healthy participants. CONCLUSION: DDD alters the ROMs of the facet joints. The rotations can increase significantly not only at the DDD levels but also at their adjacent levels when compared to those of the healthy participants. The increase in rotations did not occur around the primary rotation axis of the torso motion but around the coupled axes. This hypermobility in coupled rotations might imply a biomechanical mechanism related to DDD.