High Prevalence of Work-related Musculoskeletal Disorders and Limited Evidence-based Ergonomics in Orthopaedic Surgery: A Systematic Review.

BACKGROUND: The Centers for Disease Control defines work-related musculoskeletal disorders as disorders of the nerves, muscles, tendons, joints, spinal discs, and cartilage that are caused or exacerbated by the environment or nature of work. Previous meta-analyses have characterized work-related musculoskeletal disorders among interventionists, general surgeons, and other surgical subspecialties, but prevalence estimates, prognosis, and ergonomic considerations vary by study and surgical specialty. QUESTIONS/PURPOSES: (1) What is the career prevalence of work-related musculoskeletal disorders in orthopaedic surgeons? (2) What is the treatment prevalence associated with work-related musculoskeletal disorders in orthopaedic surgeons? (3) What is the disability burden of work-related musculoskeletal disorders in orthopaedic surgeons? (4) What is the scope of orthopaedic surgical ergonomic assessments and interventions? METHODS: A systematic review of English-language studies from PubMed, MEDLINE, Embase, and Scopus was performed in December 2022 and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies that presented prevalence estimates of work-related musculoskeletal disorders or assessed surgical ergonomics in orthopaedic surgery were included. Reviews, case reports, gray literature (conference abstracts and preprints), and studies with mixed-surgeon (nonorthopaedic) populations were excluded. The search yielded 5603 abstracts; 24 survey-based studies with 4876 orthopaedic surgeons (mean age 48 years; 79% of surgeons were men) were included for an analysis of work-related musculoskeletal disorders, and 18 articles were included for a descriptive synthesis of ergonomic assessment. Quality assessment using the Joanna Briggs Institute Tool revealed that studies had a low to moderate risk of bias, largely because of self-reporting survey-based methodology. Because of considerable heterogeneity and risk of bias, prevalence outcomes were not pooled and instead are presented as ranges (mean I 2 = 91.3%). RESULTS: The career prevalence of work-related musculoskeletal disorders in orthopaedic surgeons ranged from 37% to 97%. By anatomic location, the prevalence of work-related musculoskeletal disorders in the head and neck ranged from 4% to 74%; back ranged from 9% to 77%; forearm, wrist, and hand ranged from 12% to 54%; elbow ranged from 3% to 28%; shoulder ranged from 3% to 34%; hip and thigh ranged from 1% to 10%; knee and lower leg ranged from 1% to 31%; and foot and ankle ranged from 4% to 25%. Of orthopaedic surgeons reporting work-related musculoskeletal disorders, 9% to 33% had a leave of absence, practice restriction or modification, or early retirement, and 27% to 83% received some form of treatment. Orthopaedic surgeons experienced biomechanical, cardiovascular, neuromuscular, and metabolic stress during procedures. Interventions to improve orthopaedic surgical ergonomics have been limited, but have included robotic assistance, proper visualization aids, appropriate use of power tools, and safely minimizing lead apron use. In hip and knee arthroplasty, robotic assistance was the most effective in improving posture and reducing caloric expenditure. In spine surgery, proper use of surgical loupes was the most effective in improving posture. CONCLUSION: Although the reported ranges of our main findings were wide, even on the low end of the reported ranges, work-related musculoskeletal disability among orthopaedic surgeons appears to be a substantial concern. We recommend that orthopaedic residency training programs incorporate surgical ergonomics or work injury lectures, workshops, and film review (alongside existing film review of surgical skills) into their curricula. We suggest hospitals engage in shared decision-making with surgeons through anonymous needs assessment surveys to implement wellness programs specific to surgeons' musculoskeletal needs. We urge institutions to assess surgeon ergonomics during routine quality assessment of novel surgical instruments and workflows. LEVEL OF EVIDENCE: Level III, prognostic study.

Pedicle screw placement in the cervical vertebrae using augmented reality-head mounted displays: a cadaveric proof-of-concept study.

BACKGROUND: The accurate and safe positioning of cervical pedicle screws is crucial. While augmented reality (AR) use in spine surgery has previously demonstrated clinical utility in the thoracolumbar spine, its technical feasibility in the cervical spine remains less explored. PURPOSE: The objective of this study was to assess the precision and safety of AR-assisted pedicle screw placement in the cervical spine. STUDY DESIGN: In this experimental study, 5 cadaveric cervical spine models were instrumented from C3 to C7 by 5 different spine surgeons. The navigation accuracy and clinical screw accuracy were evaluated. METHODS: Postprocedural CT scans were evaluated for clinical accuracy by 2 independent neuroradiologists using the Gertzbein-Robbins scale. Technical precision was assessed by calculating the angular trajectory (°) and linear screw tip (mm) deviations in the axial and sagittal planes from the virtual pedicle screw position as recorded by the AR-guided platform during the procedure compared to the actual pedicle screw position derived from postprocedural imaging. RESULTS: A total of forty-one pedicle screws were placed in 5 cervical cadavers, with each of the 5 surgeons navigating at least 7 screws. Gertzbein-Robbins grade of A or B was achieved in 100% of cases. The mean values for tip and trajectory errors in the axial and sagittal planes between the virtual versus actual position of the screws was less than 3 mm and 30°, respectively (p<.05). None of the cervical screws violated the cortex by more than 2 mm or displaced neurovascular structures. CONCLUSIONS: AR-assisted cervical pedicle screw placement in cadavers demonstrated clinical accuracy comparable to existing literature values for image-guided navigation methods for the cervical spine. CLINICAL SIGNIFICANCE: This study provides technical and clinical accuracy data that supports clinical trialing of AR-assisted subaxial cervical pedicle screw placement.

Finite element analysis comparing a PEEK posterior fixation device versus pedicle screws for lumbar fusion.

BACKGROUND: Pedicle screw loosening and breakage are common causes of revision surgery after lumbar fusion. Thus, there remains a continued need for supplemental fixation options that offer immediate stability without the associated failure modes. This finite element analysis compared the biomechanical properties of a novel cortico-pedicular posterior fixation (CPPF) device with those of a conventional pedicle screw system (PSS). METHODS: The CPPF device is a polyetheretherketone strap providing circumferential cortical fixation for lumbar fusion procedures via an arcuate tunnel. Using a validated finite element model, we compared the stability and load transfer characteristics of CPPF to intact conditions under a 415 N follower load and PSS conditions under a 222 N preload. Depending on the instrumented levels, two different interbody devices were used: a lateral lumbar interbody device at L4-5 or an anterior lumbar interbody device at L5-S1. Primary outcomes included range of motion of the functional spinal units and anterior load transfer, defined as the total load through the disk and interbody device after functional motion and follower load application. RESULTS: Across all combinations of interbody devices and lumbar levels evaluated, CPPF consistently demonstrated significant reductions in flexion (ranging from 90 to 98%), extension (ranging from 88 to 94%), lateral bending (ranging from 75 to 80%), and torsion (ranging from 77 to 86%) compared to the intact spine. Stability provided by the CPPF device was comparable to PSS in all simulations (range of motion within 0.5 degrees for flexion-extension, 0.6 degrees for lateral bending, and 0.5 degrees for torsion). The total anterior load transfer was higher with CPPF versus PSS, with differences across all tested conditions ranging from 128 to 258 N during flexion, 89-323 N during extension, 135-377 N during lateral bending, 95-258 N during torsion, and 82-250 N during standing. CONCLUSION: Under the modeled conditions, cortico-pedicular fixation for supplementing anterior or lateral interbody devices between L4 and S1 resulted in comparable stability based on range of motion measures and less anterior column stress shielding based on total anterior load transfer measures compared to PSS. Clinical studies are needed to confirm these finite element analysis findings.

Characterization of ion release from a novel biomaterial, Molybdenum-47.5Rhenium, in physiologic environments.

BACKGROUND CONTEXT: Metals from spinal implants are released into surrounding tissues by various mechanisms. Metal ion release has been associated with clinical implant failure, osteolysis, and remote site accumulation with adverse events. Significant corrosion and associated metal ion release has been described with currently used spinal implant alloys. A novel metal alloy, Molybdenum-47.5Rhenium alloy (MoRe®), was approved for use in medical implants in 2019 by the FDA. PURPOSE: To evaluate the metal ion release profile of MoRe alloy after immersion in both a stable physiologic, as well as in an inflammatory environment. STUDY DESIGN: In vitro study. METHODS: The ion release profile of the MoRe alloy was comprehensively evaluated in-vitro after prolonged immersion in physiologic and inflammatory environments. Ion concentration analyses were then conducted using inductively coupled plasma-mass spectrometry (ICP-MS) methods. Comparative testing of titanium (Ti-6Al-4V) and cobalt chromium (Co-28Cr-6Mo) was also performed. RESULTS: Under baseline physiologic conditions, the MoRe alloy demonstrates very low molybdenum and rhenium ion release rates throughout the 30-day test period. During the first time interval (day 0-1), low levels of molybdenum and rhenium ions are detected (<0.3 µg/cm2 day) followed by a rapid reduction in the ion release rates to <0.05 µg/cm2 day during the second time interval (days 1-3) followed by a further reduction to very low steady-state rates <0.01 µg/cm2 day during the third time interval (days 3-7), which were maintained through 30 days. In the inflammatory condition (H2O2 solution), there was a transient increase in the release of molybdenum and rhenium ions, followed by a return to baseline ion release rates (days 2-4), with a further reduction to low steady-state rates of ∼0.01 µg/cm2 day (days 4-8). The measured molybdenum and rhenium ion release rates in both steady state (<0.01 µg/cm2 day), and inflammatory environments (0.01 µg/cm2 day) were far below the established FDA-permitted daily exposure (PDE) of 1,900 µg/cm2 day for molybdenum and 4,400 µg/cm2 day for rhenium. In contrast, titanium and cobalt chromium approached or exceeded their established PDE values in an inflammatory environment. CONCLUSIONS: The novel biomaterial MoRe demonstrated a lower metal ion release profile in both a physiologic and inflammatory environment and was well below the established PDE.  Comparative testing of the cobalt-chromium and titanium alloys found higher levels of ion release in the inflammatory environment that exceeded the PDE for cobalt and vanadium.

Metal-Free Cortico-Pedicular Device for Supplemental Fixation in Lumbar Interbody Fusion.

OBJECTIVE: Pedicle screw fixation is a commonly utilized adjunct for lumbar interbody fusion, yet risks include screw malposition, pullout, loosening, neurovascular injury, and stress transfers leading to adjacent segment degeneration. This report describes the preclinical and initial clinical results of a minimally invasive, metal-free cortico-pedicular fixation device used for supplemental posterior fixation in lumbar interbody fusion. METHODS: Safety of arcuate tunnel creation was evaluated in cadaveric lumbar (L1-S1) specimens. A finite element analysis study evaluated clinical stability of the device to pedicular screw-rod fixation at L4-L5. Preliminary clinical results were assessed by analysis of Manufacturer and User Facility Device Experience database complications, and 6-month outcomes in 13 patients treated with the device. RESULTS: Among 35 curved drill holes in 5 lumbar specimens, no breaches of the anterior cortex were identified. The mean minimum distance from the anterior surface of the hole to the spinal canal ranged from 5.1 mm at L1-L2 to 9.8 mm at L5-S1. In the finite element analysis study, the polyetheretherketone strap provided comparable clinical stability and reduced anterior stress shielding compared to the conventional screw-rod construct. The Manufacturer and User Facility Device Experience database identified 1 device fracture with no clinical sequelae among 227 procedures. Initial clinical experience showed a 53% decrease in pain severity (P = 0.009), a 50% decrease in Oswestry Disability Index (P < 0.001), and no device-related complications. CONCLUSIONS: Cortico-pedicular fixation is a safe and reproducible procedure that may address limitations of pedicle screw fixation. Longer term clinical data in large clinical studies are recommended to confirm these promising early results.

Can a Spine Robot Be More Efficient and Less Expensive While Maintaining Accuracy?

BACKGROUND: Spinal surgical robots are in the early phases of development and adoption. These systems need to be easier to use, less costly, and more workflow-efficient. METHODS: A portable, operating room table-mounted spine robot and camera system are described. Accuracy and workflow efficiency were assessed in comparison to another commonly utilized spinal robotic system. RESULTS: For the surgical task of inserting 4 pedicle screws into 2 adjacent lumbar vertebrae, equivalent accuracy was seen with both systems. The new robotic system was more efficient in terms of total procedure time, system setup time, and screw planning to in-position time (p<0.05). CONCLUSIONS: Spinal robotic systems can be more efficient and less expensive while maintaining accuracy. CLINICAL RELEVANCE: Spinal robots are being increasingly utilized in clinical practice. Lowering the cost of these systems and increasing their workflow efficiency should help patients and spine surgeons alike.

Ninety-day complication, revision, and readmission rates for current-generation robot-assisted thoracolumbar spinal fusion surgery: results of a multicenter case series.

OBJECTIVE: Robotics is a major area for research and development in spine surgery. The high accuracy of robot-assisted placement of thoracolumbar pedicle screws is documented in the literature. The authors present the largest case series to date evaluating 90-day complication, revision, and readmission rates for robot-assisted spine surgery using the current generation of robotic guidance systems. METHODS: An analysis of a retrospective, multicenter database of open and minimally invasive thoracolumbar instrumented fusion surgeries using the Mazor X or Mazor X Stealth Edition robotic guidance systems was performed. Patients 18 years of age or older and undergoing primary or revision surgery for degenerative spinal conditions were included. Descriptive statistics were used to calculate rates of malpositioned screws requiring revision, as well as overall complication, revision, and readmission rates within 90 days. RESULTS: In total, 799 surgical cases (Mazor X: 48.81%; Mazor X Stealth Edition: 51.19%) were evaluated, involving robot-assisted placement of 4838 pedicle screws. The overall intraoperative complication rate was 3.13%. No intraoperative implant-related complications were encountered. Postoperatively, 129 patients suffered a total of 146 complications by 90 days, representing an incidence of 16.1%. The rate of an unrecognized malpositioned screw resulting in a new postoperative radiculopathy requiring revision surgery was 0.63% (5 cases). Medical and pain-related complications unrelated to hardware placement accounted for the bulk of postoperative complications within 90 days. The overall surgical revision rate at 90 days was 6.63% with 7 implant-related revisions, representing an implant-related revision rate of 0.88%. The 90-day readmission rate was 7.13% with 2 implant-related readmissions, representing an implant-related readmission rate of 0.25% of cases. CONCLUSIONS: The results of this multicenter case series and literature review suggest current-generation robotic guidance systems are associated with low rates of intraoperative and postoperative implant-related complications, revisions, and readmissions at 90 days. Future outcomes-based studies are necessary to evaluate complication, revision, and readmission rates compared to conventional surgery.

Role of Robotics in Adult Spinal Deformity.

Robotic-assisted adult deformity surgery has played a rapidly expanding role since its introduction. As robotic spine technologies improve, the potential to limit complications and morbidity is vast. The improvements in instrumentation accuracy combined with the ability to maintain that accuracy in multiple positions allow creative surgical approaches and techniques that can limit operative time, blood loss, and improve outcomes. In the years to come, robotic-assisted spine surgery and navigation will likely play an expanding role that continues to be defined. LEVEL OF EVIDENCE: 5, expert opinion.

Ectopic bone formation in the pelvis after combined anterior and posterior fusion of the spine with osteogenic protein-1 use: a case report.

STUDY DESIGN: Case report. OBJECTIVE: We report the first described case of ectopic bone formation with osteogenic protein-1 (OP-1) use occurring in the pelvis after combined anterior and posterior spinal fusion. SUMMARY OF BACKGROUND DATA: OP-1 is a member of the transforming growth factor-beta superfamily of extracellular proteins involved in bone growth and formation. Potential side effects of OP-1 are not yet fully understood, and clinical data have failed to show significant adverse effects of OP-1. METHODS: The patient had flat-back syndrome with symptomatic junctional degenerative disease below the level of fusion and underwent staged anterior and posterior reconstruction. OP-1 was used in conjunction with local bone graft and crushed cancellous allograft in both anterior and posterior procedures. RESULTS: Bone grew adjacent to the left superior pubic rami, extending through the left rectus sheath and into the left psoas muscle. Subsequently, complete excision of the ectopic bone was performed. No local recurrence was noted at postoperative visits up to 5 months after excision. At that time, the patient had returned to work and was pleased with the level of function. CONCLUSIONS: Caution is justified with the use of OP-1. Clinical studies must be conducted to ensure appropriate dosing to prevent ectopic bone formation and deleterious effects.

Successful treatment of thoracolumbar fractures with short-segment pedicle instrumentation.

STUDY DESIGN: Retrospective radiographic review. OBJECTIVE: To determine whether clinical factors or common classification systems can predict the radiologic outcome of short-segment thoracolumbar fracture fixation. SUMMARY OF BACKGROUND DATA: Previous reports have indicated that short-segment thoracolumbar fracture fixation might not be appropriate for highly comminuted fractures or for patients with multiple traumatic injuries. METHODS: We conducted a retrospective radiographic review of 46 thoracolumbar fractures treated with short-segment posterior instrumentation to determine the rate of correction loss and instrumentation failure in relation to the Load Sharing Classification of Spine Fracture system and the AO Classification of Fractures system. No postoperative bracing was used. Patients with multisystem organ trauma and those with isolated injuries were included. RESULTS: An average loss of correction of 7.5 degree was observed. Pedicle screw placement into the fractured vertebra seemed to protect against correction loss: 4 of the 7 patients (57%) in the no intermediate fixation group had >10 degree loss of correction. No relationship was shown between loss of correction and Load Sharing Classification (< or = 6 or > or = 7 points), loss of correction and AO Classification, or loss of correction and level of injury (thoracolumbar junction vs. lower lumbar). CONCLUSIONS: With modern instrumentation and techniques, short-segment thoracolumbar fracture fixation could be used successfully, despite highly comminuted injuries, without anterior column support or supplemental bracing.

A cadaveric precision and accuracy analysis of augmented reality-mediated percutaneous pedicle implant insertion.

OBJECTIVE: Augmented reality-mediated spine surgery (ARMSS) is a minimally invasive novel technology that has the potential to increase the efficiency, accuracy, and safety of conventional percutaneous pedicle screw insertion methods. Visual 3D spinal anatomical and 2D navigation images are directly projected onto the operator's retina and superimposed over the surgical field, eliminating field of vision and attention shift to a remote display. The objective of this cadaveric study was to assess the accuracy and precision of percutaneous ARMSS pedicle implant insertion. METHODS: Instrumentation was placed in 5 cadaveric torsos via ARMSS with the xvision augmented reality head-mounted display (AR-HMD) platform at levels ranging from T5 to S1 for a total of 113 total implants (93 pedicle screws and 20 Jamshidi needles). Postprocedural CT scans were graded by two independent neuroradiologists using the Gertzbein-Robbins scale (grades A-E) for clinical accuracy. Technical precision was calculated using superimposition analysis employing the Medical Image Interaction Toolkit to yield angular trajectory (°) and linear screw tip (mm) deviation from the virtual pedicle screw position compared with the actual pedicle screw position on postprocedural CT imaging. RESULTS: The overall implant insertion clinical accuracy achieved was 99.1%. Lumbosacral and thoracic clinical accuracies were 100% and 98.2%, respectively. Specifically, among all implants inserted, 112 were noted to be Gertzbein-Robbins grade A or B (99.12%), with only 1 medial Gertzbein-Robbins grade C breach (> 2-mm pedicle breach) in a thoracic pedicle at T9. Precision analysis of the inserted pedicle screws yielded a mean screw tip linear deviation of 1.98 mm (99% CI 1.74-2.22 mm) and a mean angular error of 1.29° (99% CI 1.11°-1.46°) from the projected trajectory. These data compare favorably with data from existing navigation platforms and regulatory precision requirements mandating that linear and angular deviation be less than 3 mm (p < 0.01) and 3° (p < 0.01), respectively. CONCLUSIONS: Percutaneous ARMSS pedicle implant insertion is a technically feasible, accurate, and highly precise method.

Central cord syndrome.

Central cord syndrome is the most common type of incomplete spinal cord injury. This syndrome most often occurs in older persons with underlying cervical spondylosis caused by a hyperextension mechanism. It also occurs in younger persons who sustain trauma to the cervical spine and, less commonly, as a result of nontraumatic causes. The upper extremities are more affected than the lower extremities, with motor function more severely impaired than sensory function. Central cord syndrome presents a spectrum, from weakness limited to the hands and forearms with sensory preservation, to compete quadriparesis with sacral sparing as the only evidence of incomplete spinal cord injury. Historically, treatment has been nonsurgical, but recovery is often incomplete. Early surgical treatment of central cord syndrome remains controversial. However, recent studies have shown benefits, particularly of early surgery to decompress the spinal cord in patients with pathologic conditions revealed by radiography or MRI.

Comparison of computed tomography and plain radiography in assessing traumatic spinal deformity.

STUDY DESIGN: An imaging study assessing agreement between computed tomographic (CT) scans and plain radiographs when measuring acute thoracolumbar spinal deformity. OBJECTIVE: To compare the ability of the screening CT scans to measure spinal deformity in the thoracolumbar spine with that of portable plain radiographs. SUMMARY OF BACKGROUND DATA: At the time of arrival at many trauma centers, patients undergo screening whole body CT as the initial imaging evaluation for trauma. The thoracolumbar spine is well visualized on both coronal and sagittal reconstructions. METHODS: Images of patients who underwent screening CT and portable supine plain radiography of thoracolumbar fractures were reviewed. Four observers, at 2 separate times, measured pathologic kyphosis and scoliosis on each image by using the Cobb method. Data were analyzed for statistical differences. RESULTS: In the sagittal plane, screening CT scans and plain radiographs showed an average mean difference of -1.13 degrees+/-SD of 3.76 degrees. In the coronal plane, CT scans and radiographs showed an average mean difference of 0.10 degrees+/-SD of 2.52 degrees. The interobserver correlation coefficients among the 4 observers were 0.913 in the sagittal plane and 0.953 in the lateral plane, indicating excellent interobserver correlation. CONCLUSIONS: Screening CT demonstrates excellent correlation with plain radiography for measuring thoracolumbar spinal deformity in the coronal and sagittal planes for patients with trauma.

Acute cervical osteomyelitis and prevertebral abscess after routine tonsillectomy.

BACKGROUND CONTEXT: Tonsillectomy is among the most commonly performed surgical procedures. The development of severe infection after tonsillectomy is a very rare but potentially fatal complication that has not been described in the orthopedic, neurosurgical, or spine literature. PURPOSE: To present acute cervical osteomyelitis and prevertebral abscess formation as a complication of a routine tonsillectomy. STUDY DESIGN: Case report, literature review. METHODS: A case report was prepared on the clinical and radiographic data of a patient presenting with prevertebral abscess and acute cervical osteomyelitis 6 weeks after routine tonsillectomy. A review of relevant literature was additionally performed. RESULTS: The patient presented 6 weeks after tonsillectomy with evidence of a deep cervical infection. Operative debridement with anterior and posterior surgical stabilization was performed. The patient completed a 6-week course of intravenous antibiotics. At 24-month follow-up, the patient showed no signs of infection and demonstrated a stable fusion mass. CONCLUSIONS: The development of prevertebral abscess and acute cervical osteomyelitis has been discussed in a small number of otolaryngology case reports and has not been previously reported in the orthopedic, neurosurgical, or spine literature. Symptoms may be nonspecific, and so a high index of clinical suspicion is needed. Delay in treatment may lead to significant morbidity and even mortality. Successful treatment can be obtained through operative debridement and intravenous antibiotic therapy.

Degenerative cervical spondylosis: clinical syndromes, pathogenesis, and management.

Degenerative changes in the cervical spinal column are ubiquitous in the adult population, but infrequently symptomatic. The evaluation of patients with symptoms is facilitated by classifying the resulting clinical syndromes into axial neck pain, cervical radiculopathy, cervical myelopathy, or a combination of these conditions. Although most patients with axial neck pain, cervical radiculopathy, or mild cervical myelopathy respond well to initial nonsurgical treatment, those who continue to have symptoms or patients with clinically evident myelopathy are candidates for surgical intervention.

The meniscal ossicle revisited: etiology and an arthroscopic technique for treatment.

We describe a new arthroscopic technique for repair of meniscal ossicles in support of the theory that meniscal ossicles are traumatic in nature. Using a standard inferolateral portal, the arthroscope is passed under the posterior cruciate ligament to permit visualization of the "root" of the medial meniscus with a matching donor lesion on the tibia. A limited debridement should be performed of the donor site as well as the posterior horn of the meniscus if it has healed over with fibrocartilage to allow bone-to-bone healing. A posteromedial working portal is made at an angle amenable to the repair and a 6-mm cannula is placed. A Beath passing pin commonly used for anterior cruciate ligament reconstruction is used to pass suture for the outside-inside-out repair. The pin is passed through the cannula in the posterior medial portal. The root of the medial meniscus and the avulsed ossicle are pierced with the Beath pin and tensioned, after which the pin is drilled into the matching donor site and out through the tibia. Two passes are used to create a mattress suture through the ossicle, and the suture is tied over a bone bridge on the anterolateral tibia.

Acute hip pain in the nonambulatory infant: Salter-Harris type I fracture in the capital femoral epiphysis without a traumatic history.

An otherwise healthy 11-month-old girl was brought to the hospital after her parents noted the acute onset of right hip pain and refusal to bear weight. No abnormalities were seen in the initial radiographs, laboratory values were within reference range, and noninvasive workup was negative for septic arthritis. The parents reported a recent minor fall from a standing position, but stated that the child seemed to return to normal without pain after a few minutes of crying. A hemarthrosis without purulence was found upon joint aspiration, and the patient improved significantly after administration of anti-inflammatory medication. Follow-up radiographs 13 days after initial presentation showed an extremely rare Salter-Harris type I proximal physeal fracture well into the healing process.

Multiexpandable cage for minimally invasive posterior lumbar interbody fusion.

The increasing adoption of minimally invasive techniques for spine surgery in recent years has led to significant advancements in instrumentation for lumbar interbody fusion. Percutaneous pedicle screw fixation is now a mature technology, but the role of expandable cages is still evolving. The capability to deliver a multiexpandable interbody cage with a large footprint through a narrow surgical cannula represents a significant advancement in spinal surgery technology. The purpose of this report is to describe a multiexpandable lumbar interbody fusion cage, including implant characteristics, intended use, surgical technique, preclinical testing, and early clinical experience. Results to date suggest that the multiexpandable cage allows a less invasive approach to posterior/transforaminal lumbar interbody fusion surgery by minimizing iatrogenic risks associated with static or vertically expanding interbody prostheses while providing immediate vertebral height restoration, restoration of anatomic alignment, and excellent early-term clinical results.

A novel total knee arthroplasty infection model in rabbits.

Infection of biomaterial implants is an expensive and devastating complication of orthopaedic surgery historically ranging from less than 1% in primary total knee arthroplasty (TKA) to 10% in revision TKA. An in vivo animal model was developed to test the efficacy of innovative therapies for the prevention of biomaterial centered infections caused by methicillin-resistant Staphylococcus aureus bacteria (MRSA). Twenty-two New Zealand White rabbits were used in this study. After proper anesthesia, a stainless-steel screw with a high molecular weight polyethylene (UHMWPE) washer was cemented in a defect created in the intra-articular, non-articulating portion of the lateral femoral condyle of each knee. After closure of the joint capsule, each knee was inoculated with 0, 10(2), 10(3), or 10(4) colony forming units (CFU) of MRSA. Animals were sacrificed after 7 days at which time joint aspirate, tissues and biomaterial samples were examined for evidence of infection. A total of 42 knees were used for analysis. When saline was injected into the knee, 0/10 of the knees demonstrated evidence of biomaterial centered infection (with the contralateral knee receiving 10(4)CFU MRSA). Four of 10 knees developed a biomaterial centered infection when 10(2)CFU MRSA was introduced. Seven out of 10 knees developed a biomaterial centered infection when either 10(3) or 10(4)CFU MRSA was injected. No evidence of septicemia (positive blood cultures) was found in any animal. This rabbit knee model utilizes commonly employed inexpensive orthopaedic implant materials in an in vivo milieu and provides an effective method for the evaluation of treatments for biomaterial centered infections.