Biomechanical evaluation of transfacet screw fixation for stabilization of multilevel cervical corpectomies.

STUDY DESIGN: Cadaveric biomechanical investigation. OBJECTIVES: To test the feasibility of transfacet screws as a minimally invasive posterior fixation device for the cervical spine by comparing the biomechanical stability of transfacet screws to lateral mass screws and rods in a multilevel cervical corpectomy model. SUMMARY OF BACKGROUND DATA: Minimally invasive surgery (MIS) of the spine has gained increasing acceptance and popularity. However, a minimally invasive means of instrumenting the posterior cervical spine has yet to be discovered. Posterior transfacet screws have been described as a means of posterior fixation. In addition, they have the potential of being placed percutaneously through stab incisions. However, validation of transfacet screws in an unstable cervical model in which posterior instrumentation may be necessary has not been carried out till date. METHODS: Sixteen cadaveric cervical spines were randomized to transfacet or lateral mass instrumentation groups. The spines were tested in the following conditions: (a) intact, (b) after multilevel corpectomies with strut graft placement with stand-alone posterior fixation, and (c) with an additional anterior plate over the strut graft. Corpectomy site loading was measured with a custom-designed strut graft. Data were collected for spinal stiffness, range of motion, and strut graft loading, and was analyzed using 2-way analysis of variance (P<0.05). RESULTS: Stand-alone transfacet screw fixation was found to provide inferior spinal stability and resulted in increased spinal motion and graft loading compared with the other constructs (P<0.05 for all). CONCLUSIONS: It is unclear what kind of mechanical stiffness is necessary to stabilize the cervical spine and obtain solid fusion. However, decreased stability and increased graft loading suggest that transfacet screws may not be the ideal method of posterior fixation to supplement multilevel anterior cervical corpectomies and fusions despite their potential as a minimally invasive method for posterior cervical instrumentation.

Comparison of three methods for measuring intracompartmental pressure in injured limbs of trauma patients.

OBJECTIVES: To compare three commonly used methods and devices developed for measurement of intracompartmental pressure in injured limbs. SETTING: Level II regional trauma center. PATIENTS/PARTICIPANTS: Consecutive patients treated for extremity trauma suspected to have compartment syndrome. INTERVENTION: Analysis of compartment pressure data collected using 1) a solid-state transducer intracompartmental catheter; 2) an electronic transducer-tipped catheter; and 3) a modification of Whitesides' needle manometer technique using a straight 18-gauge needle, arterial line transducer, and central venous pressure monitor. All measurements were performed in random order within an area 1.5 cm in diameter. MAIN OUTCOME MEASUREMENTS: Statistical analysis evaluating differences in measured data between methods and whether choice of method might alter treatment. RESULTS: Intracompartmental pressure was measured by each method in 97 muscle compartments in 31 injured limbs of 26 trauma patients suspected to have a compartment syndrome. The overall intraclass correlation coefficient for the three methods was 0.83 (range, 0.77-0.88), indicating only satisfactory agreement among the methods. The mean difference among measurements in each compartment was 8.3 mm Hg (range, 0-51 mm Hg), including 81 (27%) major differences exceeding 10 mm Hg and 72 (24%) minor differences of 6 to 10 mm Hg. CONCLUSIONS: The methods were similar but not completely reliable for measuring intracompartmental pressure in trauma patients. Although all methods appeared useful as aids in diagnosis of compartment syndrome, intracompartmental pressure data, especially single readings, must be interpreted in view of clinical findings.

Infection prevention in total knee and total hip arthroplasties.

Infection after primary joint arthroplasty is responsible for severe morbidity to the patients and staggering costs to society. Understanding the patient population undergoing these procedures and the use of appropriate prophylactic regiments and precautions in the perioperative and postoperative periods is crucial for the ultimate success of the procedures. In this article, we review the current related literature and our techniques for reducing the likelihood of infection after total knee and total hip arthroplasties.

Minimally invasive plating of high-energy metaphyseal distal tibia fractures.

OBJECTIVE: The purpose of this study is to evaluate clinical results and outcomes of a strict cohort of high-energy injuries of the metaphyseal distal tibia with minimal or no intraarticular involvement treated using the minimally invasive plating concept. SETTING: Level II trauma center. DESIGN: Retrospective analysis of a consecutive case series with limb-specific and whole-person outcomes measures. INTERVENTION: Minimally invasive medial plating for high-energy metaphyseal fractures of the distal tibia with little or no intraarticular involvement. MAIN OUTCOME MEASUREMENT: Clinical and radiographic results were assessed at a minimum of 1 year, and outcomes measures were applied at final follow-up at a minimum of 2 years. Limbs were assessed with the American Orthopaedic Foot and Ankle Surgeons (AOFAS) ankle-hindfoot instrument and the method of Olerud and Molander. Patient outcomes were evaluated with the Short Form-36 (SF-36) and the Musculoskeletal Functional Assessment (MFA). RESULTS: Twenty-six patients were followed until healed at an average of 36 months (12-56 months). Mean fracture healing time was 35 weeks (12-112 weeks) with acceptable alignment restored (angulation2 years were comparable to normative data of patients with uninjured limbs, whereas MFA results showed functional deficits in 4 of 10 subsections. CONCLUSIONS: Minimally invasive medial plating will restore limb alignment and yield successful clinical outcomes for high-energy metaphyseal fractures of the distal tibia. Despite the significant reoperation rate and prolonged time to union, most patients can expect a predictable return of function. Strong consideration should be given to adjunctive measures in at-risk patients, including those with highly comminuted fracture patterns, bone loss, or Type II or III open fractures.

Comparing pain reduction following kyphoplasty and vertebroplasty for osteoporotic vertebral compression fractures.

BACKGROUND: Osteoporosis with subsequent osteoporotic vertebral compression fractures is an increasingly important disease due not only to its significant economic impact but also to the increasing age of our population. Pain reduction and stabilization are of primary importance with osteoporotic vertebral compression fractures. Although many patients heal with conservative treatment consisting of rest or activity modification, analgesics, and bracing, the management of severe pain compels some patients to seek surgical intervention via 2 procedures: vertebroplasty and kyphoplasty. Although there is abundant support in the literature for both procedures, there remains debate over which procedure can most successfully reduce patients' perception of pain. OBJECTIVE: To determine the amount of pain reduction using the visual analog scale (VAS) with kyphoplasty and vertebroplasty in the treatment of osteoporotic vertebral compression fractures. DESIGN: Meta-analysis METHODS: A systematic review and meta-analysis of the available literature was performed to quantify the amount of pain reduction using the visual analog scale (VAS) between vertebroplasty and kyphoplasty for osteoporotic vertebral compression fractures. RESULTS: Twenty-one studies, 14 vertebroplasty and 7 kyphoplasty, qualified for inclusion representing totals of 1,046 vertebroplasty and 263 kyphoplasty patients treated, respectively. Kyphoplasty and vertebroplasty resulted in a more than 5 point drop in the VAS in the immediate postoperative period (p<0.00001). Between the two, the difference in early pain relief was not significant. At final follow-up, the long-term VAS was improved for both procedures, but the final follow-up VAS for vertebroplasty and kyphoplasty was not significant when compared to the initial postoperative VAS (p=0.25, p=0.38, respectively). CONCLUSIONS: The analysis demonstrates that both procedures reduce the amount of pain in the immediate postoperative period by approximately 50%. Both procedures reduce pain in symptomatic osteoporotic vertebral compression fractures that have failed conservative treatment. Randomized controlled trials are needed to provide definitive data on which procedure is the most effective for vertebral compression fractures.