Transcranial magnetic stimulation in the semi-quantitative, pre-operative assessment of patients undergoing spinal deformity surgery

PURPOSE

To compare measurements of motor evoked potential latency stimulated either magnetically (mMEP) or electrically (eMEP) and central motor conduction time (CMCT) made pre-operatively in conscious patients using transcranial and intra-operatively using electrical cortical stimulation before and after successful instrumentation for the treatment of adolescent idiopathic scoliosis.

METHODS

A group initially of 51 patients with adolescent idiopathic scoliosis aged 12-19 years was evaluated pre-operatively in the outpatients' department with transcranial magnetic stimulation. The neurophysiological data were then compared statistically with intra-operative responses elicited by transcranial electrical stimulation both before and after successful surgical intervention. MEPs were measured as the cortically evoked compound action potentials of Abductor hallucis. Minimum F-waves were measured using conventional nerve conduction methods and the lower motor neuron conduction time was calculated and this was subtracted from MEP latency to give CMCT.

RESULTS

Pre-operative testing was well tolerated in our paediatric/adolescent patients. No neurological injury occurred in any patient in this series. There was no significant difference in the values of mMEP and eMEP latencies seen pre-operatively in conscious patients and intra-operatively in patients under anaesthetic. The calculated quantities mCMCT and eCMCT showed the same statistical correlations as the quantities mMEP and eMEP latency.

CONCLUSIONS

The congruency of mMEP and eMEP and of mCMCT and eCMCT suggests that these measurements may be used comparatively and semi-quantitatively for the comparison of pre-, intra-, and post-operative spinal cord function in spinal deformity surgery.

Metastatic spinal cord syndromes: imaging appearances and treatment planning

Metastatic spinal cord syndromes usually result from neural compression by adjacent vertebral disease but are occasionally caused by intradural or intramedullary disease. MRI is the most accurate method for evaluation of such syndromes. Knowledge of the relevant imaging appearances and therapeutic options enables the radiologist to make an accurate assessment of the extent of disease and contribute information relevant to treatment planning.

Implant-related fractures of the femur following hip fracture surgery

BACKGROUND

Most hip fractures are treated surgically, with use of either internal fixation or prosthetic replacement of the femoral head. The presence of these implants increases the risk of a later femoral fracture in susceptible osteoporotic patients. The purpose of this study was to analyze the incidence of and risk factors for implant-related fractures of the femur after previous hip fracture surgery.

METHODS

Over a ten-year period from January 1988 to December 1997, 6230 patients (median age, eighty-two years; male:female ratio, 1247:4983) who sustained a total of 6696 hip fractures were admitted to the Edinburgh Orthopaedic Trauma Unit. Demographic information on the patients and details of the original treatment of the hip fracture were prospectively coded and entered into a trauma database. All subsequent readmissions due to a femoral fracture related to the implant were prospectively audited and extracted for the purposes of this study.

RESULTS

One hundred and forty-one patients sustained an ipsilateral fracture of the femur at a median of twenty-four weeks following the original hip fracture surgery. Survivorship analysis of the hip fracture population revealed an overall rate of subsequent femoral fracture of 2.9% at five years, which increased to 5.1% at ten years. The median age and gender distribution of the patients who sustained a subsequent femoral fracture were similar to those of the hip fracture population as a whole. Two-thirds of the fractures propagated from the tip of the implant. Analysis of the subsequent fractures according to the type of implant used to treat the original fracture revealed considerable differences in incidence. The incidence was relatively high in the patients initially treated with a Gamma nail (18.74 fractures per 1000 person-years) or a cementless hemiarthroplasty (11.72 per 1000 person-years) and was relatively low in those treated with a compression hip screw (4.46 per 1000 person-years), cannulated screws (4.50 per 1000 person-years), or a primary arthroplasty with cement (6.2 per 1000 person-years). The highest incidence of fracture was seen in the patients who had required an arthroplasty with cement as a revision procedure following failure of a primary implant (22.39 per 1000 person-years).

CONCLUSIONS

Implant-related fractures following hip fracture surgery are more common than has previously been appreciated. The risk of later ipsilateral femoral fracture is increased by the use of a Gamma nail or a cementless hemiarthroplasty to treat the original hip fracture.

Prospective randomized controlled trial of an intramedullary nail versus dynamic screw and plate for intertrochanteric fractures of the femur

OBJECTIVES

To compare the surgical complications and functional outcome of the Gamma nail intramedullary fixation device versus the Richards sliding hip screw and plate device in intertrochanteric femoral fractures.

DESIGN

A prospective, randomised controlled clinical trial with observer blinding.

SETTING

A regional teaching hospital in the United Kingdom.

PATIENTS

All patients admitted from the local population with intertrochanteric fractured femurs were included. There were 400 patients entered into the study and 399 followed-up to one year or death.

INTERVENTION

The devices were assigned by randomization to either a short-type Gamma nail (203 patients) or a Richard's-type sliding hip screw and plate (197 patients).

MAIN OUTCOME MEASUREMENTS

The main surgical outcome measurements were fixation failure and reoperation. A functional outcome of pain, mobility status, and range of movement were assessed until one year.

RESULTS

The requirement for revision in the Gamma nail group was twelve (6%); for Richard's group, eight (4%). This was not statistically different (p = 0.29; odds ratio, 1.48 [0.59-3.7]). A subcapital femoral fracture occurred in the Richard's group. Femoral shaft fractures occurred with four in the Gamma nail group (2%) and none in the Richard's group (p = 0.13). Three required revision to another implant. Lag-screw cut-out occurred in eight patients in the gamma nail group (4%) and four in the Richard's group (2%). This was not statistically significant (p = 0.37; odds ratio, 2.29 [0.6-9.0]). The development of other postoperative complications was the same in both groups. There was no difference between the two groups in terms of early or long-term functional status at one year.

CONCLUSIONS

The use of an intramedullary device in the treatment of intertrochanteric femoral fractures is still associated with a higher but nonsignificant risk of postoperative complications. Routine use of the Gamma nail in this type of fracture cannot be recommended over the current standard treatment of dynamic hip screw and plate.

Interdigital pilonidal sinus in the hand

We report three cases of interdigital pilonidal sinus including a case of a woman with this condition. Previous reports that surgical excision is curative in all cases are not supported by our experience.

Cigarette smoking and open tibial fractures

Complication rates were compared in 140 smoking and 133 non-smoking patients with open tibial fractures. Both the groups were evenly matched demographically and in terms of primary fracture treatment. Flap failure complicated 7 (20%) patients in the smoking group and 4 (14%) in the non-smoking group. The mean time to union was 32 weeks for smokers and 28 weeks for non-smokers (P<0.05). Bone grafting to stimulate union was required in 36 (26%) smoking patients compared with 24 (18%) non-smoking patients. In patients treated by intramedullary nailing exchange, nailing to achieve union was carried out in 24 (38%) smoking cases compared with 13 (26%) of non-smoking cases. Smoking is associated with an increased risk of complications in patients with open tibial fractures. There is an increased rate of flap failure, delayed union and non-union. We recommend patients with open tibial fractures should be advised to stop smoking to minimise these complications.

Late fracture of the hip after reamed intramedullary nailing of the femur

In a consecutive series of 498 patients with 528 fractures of the femur treated by conventional interlocking intramedullary nailing, 14 fractures of the femoral neck (2.7%) occurred in 13 patients. The fracture of the hip was not apparent either before operation or on the immediate postoperative radiographs. It was diagnosed in the first two weeks after operation in three patients and after three months in the remainder. Age over 60 years at the time of the femoral fracture and female gender were significantly predictive of hip fracture on bivariate logistic regression analysis, but on multivariate analysis only the location of the original fracture in the proximal third of the femur (p = 0.0022, odds ratio = 6.96, 95% CI 2.01 to 24.14), low-energy transfer (p = 0.0264, odds ratio = 15.56, 95% CI 1.38 to 75.48) and the severity of osteopenia on radiographs (p = 0.0128, odds ratio = 7.55, 95% CI 1.54 to 37.07) were significant independent predictors of later fracture. Five of the 19 women aged over 60 years, who sustained an osteoporotic proximal diaphyseal fracture of the femur during a simple fall, subsequently developed a fracture of the neck. Eleven of the hip fractures were displaced and intracapsular and, in view of the advanced age of most of these patients, were usually treated by replacement arthroplasty. Reduction and internal fixation was used to treat the remaining three intertrochanteric fractures. Three patients developed complications requiring further surgery; five died within two years of their fracture.