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Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_15 | Pages 31 - 31
1 Oct 2014
Prempeh EM Grover H Inaparthy P Lutchman L Rai AM Crawford RJ
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To determine whether neurophysiological electrical pedicle testing (EPT) is a useful aid in the detection of malpostioned pedicle screw tracts

EPT data from 246 screws in 32 spinal operations on 32 patients over a 5 year period (2009–2014) were recorded and analysed. In addition to physical palpation, a ball-tipped electrode delivered stimuli and the output was recorded by evoked electromyogram (EMG). When breach threshold values were recorded, the surgeon rechecked the tract for breaches and responded appropriately. In addition, standard motor evoked potential (MEP) and sensory evoked potential(SEP) spinal cord monitoring was performed.

There were 24(9.8%) pedicle breaches by tract testing and 8(3.3%) by screw testing. In 11 instances in 7 patients where the tract testing showed a breach, the tract was redirected and subsequent screw testing showed adequate integrity of the pedicle. The total time for tract and screw testing was 25 seconds.

There were no associated changes in MEP or SEP monitoring with any of the recorded pedicle breaches and none of the patients had any post-operative neurological deficit.

EPT for the pedicle screw and tract is a safe, simple, practical and reliable technique which improves the accuracy of screw placement. Further studies would be required to confirm (and possibly revise) the threshold levels and to demonstrate whether EPT reduces the risk of misplaced screws or post-operative neurological deficit.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 536 - 536
1 Aug 2008
Prempeh EM Cherry R
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Introduction: The American Society of Anesthesiologists (ASA) grade is supposed to accurately predict morbidity and mortality. We wanted to better inform our patients of their risk of mortality in elective operations.

Method: Analysis of data from Galen (Theatre management software) routinely gathered as part of the preoperative assessment of patients. We linked this to the Date of Death field in the Hospital Master Patient index to identify those patients who had died within 90 days of surgery, including deaths after discharge from hospital.

Results: Two thousand and thirty one patients over two years. These were elective Orthopaedic operations including knee (1074) and hip (957) replacements, both primary and revision. There were thirty one mortalities over a two year period. Sixteen mortalities for knee (1.5% of knee operations) and 15 for hip surgery (1.6% of hip operations). Respective mortality for ASA grades 1–4 are presented in table below

Discussion: Our review of the 2031 patients shows that the relative risk of mortality between ASA grades 1–4 increased from 1–8.8. We examined the notes because grade 4’s mortality was 10% and realized that 75% of ASA grades recorded by Orthopaedic surgeons and anaesthetists differed. The anaesthetists seem to down grade the ASA 4’s.

Conclusion: The relative risk of mortality is lower than that as previously described. Orthopaedic surgeons seem to assess patient better when it comes to ASA grading. The paper further discusses the implications of these conclusions.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 544 - 544
1 Aug 2008
Prempeh EM Shepherd DET Costa M Cutts S
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Introduction: Many revision hip procedures involve revision of the socket only with retention of the mono block femoral component. Some surgeons choose to reduce metal wear by protecting the femoral head component from scratching by using the cut finger of a Biogel glove

Objective: To investigate whether the use of a finger surgeons glove reduces indentation of femoral (head) components.

Design: Femoral head components (Depuy) made from Ortron 90 stainless steel were fixed onto the Endura TE C 3300 materials testing machine. Indentations were made using scissors with a maximum force of 50 Newtons. Additional scratches were performed using a Jimmy. This procedure was then repeated using the finger of a glove as protection. The surface roughness values for the femoral heads were measured using a Taylor Hobson Talysurf Series 120L stylus instrument.

Conclusion: On the basis of these results we advocate the use of this simple measure to reduce the risk of surface damage to the femoral head. Furthermore, we believe that this is the only laboratory based study to ever investigate the effectiveness of this technique.