The aiming device for cervical distractor pin insertion: a proof-of-concept, feasibility study.

BACKGROUND: Restoration of cervical lordosis after anterior discectomy and fusion is a desirable goal. Proper insertion of the vertebral distraction or Caspar pin can assist lordotic restoration by either putting the tips divergently or parallel to the index vertebral endplates. With inexperienced surgeons, the traditional free-hand technique for Caspar pin insertion may require multiple insertion attempts that may compromise the vertebral body and increase radiation exposure during pin localization. Our purpose is to perform a proof-of-concept, feasibility study to evaluate the effectiveness of a pin insertion aiming device for vertebral distraction pin insertion. METHODS: A Smith-Robinson approach and anterior cervical discectomy were performed from C3 to C7 in 10 human cadaveric specimens. Caspar pins were inserted using a novel pin insertion aiming device at C3-4, C4-5, C5-6, and C6-7. The angles between the cervical endplate slope and Caspar pin alignment were measured with lateral cervical imaging. RESULTS: The average Superior Endplate-to-Caspar Pin angle (SE-CP) and the average Inferior Endplate-to-Caspar Pin angle (IE-CP) were 6.2 ± 2.0° and 6.3 ± 2.2° respectively. For the proximal pins, the SE-CP and the IE-CP were 4.0 ± 1.1°and 5.2 ± 2.4° respectively. For the distal pins, the SE-CP and the IE-CP were 7.7 ± 1.4° and 6.2 ± 2.0° respectively. No cervical endplate violations occurred. CONCLUSION: The novel Caspar pin insertion aiming device can control the pin entry points and pin direction with the average SE-CP and average IE-CP of 6.2 ± 2.0° and 6.3 ± 2.2°, respectively. The study shows that the average different angles between the Caspar pin and cervical endplate are less than 7°.

Prevalence of atypical femoral fractures in Thai patients at a single institution.

OBJECTIVE: Evaluate the prevalence of atypical femoral fracture (AFF) in Thai patients at a single institution based on the 2010 and 2013 American Society of Bone and Mineral Research (ASBMR) criteria and the sensitivity and specificity of each radiographic feature of AFF to identify bisphosphonate treatment. MATERIAL AND METHOD: The authors retrospectively reviewed plain radiographs of 856 patients who were diagnosed with subtrochanteric or femoral shaft fractures between 2002 and 2013. Only those who had major radiographic features of AFF according to the 2010 ASBMR criteria were included. Next, the prevalence of atypical fracture was recalculated based on the revised 2013 ASBMR criteria. Furthermore, the specificity and sensitivity of each radiological finding to detect bisphosphonate treatment were calculated. RESULTS: The prevalence of atypical femoral fracture based on 2010 ASBMR criteria at this institution was 5.7%. Two patients had all radiographic features of AFF but sustained a high-energy trauma and could be diagnosed with AFF based on the 2013 ASBMR criteria. Among all of the radiographic features to define AFF, a localized periosteal thickening of the lateral femoral cortex was the most specific sign to detect bisphosphonate treatment (0.98; 95% CI 0.96-0.99). CONCLUSION: The prevalence of AFF in Thai patients at a single institution was approximately 6%. Although the prevalence of AFF did not dramatically change after applying the 2013 revised ASBMR criteria, this reflected some gap in the diagnosis criteria, which should require further refinement. The authors suggested that the ASBMR criteria should be used only with those having acute fractures.