Outcome following anterior cervical discectomy in compensation patients

The Influence of Workers' Compensation Status on Patient-Reported Outcomes after Cervical Disc Arthroplasty at an Ambulatory Surgical Center

INTRODUCTION

Workers' compensation (WC) status tends to negatively affect patient outcomes in spine surgery. This study aims to evaluate the potential effect of WC status on patient-reported outcomes (PROs) after cervical disc arthroplasty (CDR) at an ambulatory surgical center (ASC).

METHODS

A single-surgeon registry was retrospectively reviewed for patients who had undergone elective CDR at an ASC. Patients with missing insurance data were excluded. Propensity score-matched cohorts were generated by the presence or lack of WC status. PROs were collected preoperatively and at 6-week, 12-week, 6-month, and 1-year time points. PROs included the Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF), visual analog scale (VAS) neck and arm pain, and Neck Disability Index. PROs were compared within and between groups. Minimum clinically important difference (MCID) achievement rates were compared between groups.

RESULTS

Sixty-three patients were included, with 36 without WC (non-WC) and 27 with WC. The non-WC cohort demonstrated postoperative improvement in all PROs at all time points, with the exception of VAS arm past the 12-week point ( P ≤ 0.030, all). The WC cohort demonstrated postoperative improvement in VAS neck at 12-week, 6-month, and 1-year time points ( P ≤ 0.025, all). The WC cohort improved in VAS arm and Neck Disability Index at the 12-week and 1-year points as well ( P ≤ 0.029, all). The non-WC cohort reported superior PRO scores in every PRO at one or more postoperative time points ( P ≤ 0.046, all). The non-WC cohort demonstrated higher rates of minimum clinically important difference achievement in PROMIS-PF at 12 weeks ( P ≤ 0.024).

CONCLUSION

Patients with WC status undergoing CDR at an ASC may report inferior pain, function, and disability outcomes compared with those with private or government-provided insurance. Perceived inferior disability in WC patients persisted into the long-term follow-up period (1 year). These findings may aid surgeons in setting realistic preoperative expectations with patients at risk of inferior outcomes.

Workers' Compensation Association With Clinical Outcomes After Anterior Cervical Diskectomy and Fusion

BACKGROUND

Research has suggested that workers' compensation (WC) status can result in poor outcomes after anterior cervical diskectomy and fusion (ACDF).

OBJECTIVE

To determine the influence WC status has on postoperative clinical outcomes after ACDF.

METHODS

A surgical database was reviewed for patients undergoing primary or revision single-level ACDF. Patients were grouped into WC vs Non-WC, and differences in baseline characteristics were assessed. Postoperative improvement was assessed for differences in mean scores between WC subgroups for visual analog scale (VAS) arm, VAS neck, 12-item Short Form Physical Composite Score, Patient-Reported Outcomes Measurement Information System physical function (PF), and Neck Disability Index (NDI) at preoperative and postoperative time points. Minimum clinically important difference (MCID) achievement was compared between groups.

RESULTS

The patient cohort included 44 with WC and 95 without. The cohort was 40% female with an average age of 48 years and mean body mass index of 30. Mean VAS arm, VAS neck, NDI, 12-item Short-Form Physical Composite Score, and Patient-Reported Outcomes Measurement Information System PF scores differed between groups; however, the difference was not sustained at the 1-yr time point. MCID achievement among WC subgroups was different for VAS arm (6 wk through 6 mo, P = .005), VAS neck (3 and 6 mo, P < .01), and NDI (3 and 6 mo, P < .05). No statistically significant difference was noted between cohorts for overall rates of MCID achievement for all patient-reported outcome measures collected.

CONCLUSION

WC patients reported similar preoperative and 1-yr postoperative neck and arm pain compared with non-WC patients after ACDF. One-yr MCID achievement rates were similar between cohorts for disability and PF scores.

Workers' Compensation Status in Association with a High NDI Score Negatively Impacts Post-Operative Dysphagia and Dysphonia Following Anterior Cervical Fusion

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) is a safe and effective procedure but has approach-related complications like postoperative dysphagia and dysphonia (PDD). Patient-reported outcome measures including the Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) have been used for the assessment of PDD. Various factors have been described that affect ACDF outcomes, and our aim was to investigate the effect of workers' compensation (WC) status.

METHODS

We included patients who underwent ACDF from 2015 to 2018 stratified according to insurance status: WC/non-WC. PDDs were assessed using the HSS-DDI score. We conducted logistic regression analyses. Statistical significance was set at P < 0.05.

RESULTS

We included 287 patients, 44 (15.33%) WC and 243 (84.67%) non-WC. A statistical comparison revealed a clinically relevant difference in the HSS-DDI total score and both subdomains (P = 0.015; dysphagia P = 0.021; dysphonia P = 0.002). Additional logistic regression analysis adjusting for preoperative Neck Disability Index scores resulted in no clinically relevant differences in the HSS-DDI total score and both subdomains (total score P = 0.420; dysphagia P = 0.531; dysphonia 0.315).

CONCLUSIONS

WC status was associated with a worse HSS-DDI score but could not be shown to be an independent risk factor for PDD. The preoperative NDI score was a strong predictor for PDD with a clinically relevant difference in the HSS DDI score (P < 0.0001). Surgeon awareness of risk factors for PDD such as WC status, even if it could not be shown as independent, is important as it may influence surgical decision making and managing patient expectations.

Assessment and Post-Intervention Recovery After Surgery for Lumbar Disk Herniation Based on Objective Gait Metrics from Wearable Devices Using the Gait Posture Index

OBJECTIVE

Surgery for lumbar disk herniation (LDH) presents an option for patients when conservative measures fail. The objective of this clinical study is to investigate a novel, objective outcome measure in patients undergoing lumbar microdiscectomy.

METHODS

Twenty-four patients were evaluated pre- and postoperatively using the Oswestry Disability Index (ODI), and a novel objective scoring tool, the Gait Posture index (GPi). The score is calculated from 4 key physical health metrics: daily step count, walking speed, step length, and walking posture. The GPi ranges from 0 (nonambulant) to 100 (excellent walking performance). Wearable accelerometers and observational recordings were used to evaluate the components of the GPi. The GPi was calculated and compared with the ODI, pre- and postintervention. The study was designed as a proof of concept and confirmation of validity for use of the GPi in LDH.

RESULTS

At follow-up (average 66 ± 36 days), 23 of 24 patients had an improvement in their GPi after surgery. The average GPi of the cohort improved from 59.33 ± 16.06 to 85.75 ± 9.22 with P < 0.001, with significant changes in all 4 components. The average preoperative ODI was 54.54 ± 20.70, improving to 16.33 ± 14.095 with P < 0.001. The Pearson correlation coefficient was r = 0.56, indicating a correlation between change in ODI and change in GPi.

CONCLUSIONS

The GPi score is a new, objective descriptor of mobility in spinal surgery which can be used to augment traditional subjective outcome scoring surveys such as the ODI. Significant changes are seen in the GPi and its constituent metrics in patients undergoing surgery for LDH.

Objective monitoring of activity and Gait Velocity using wearable accelerometer following lumbar microdiscectomy to detect recurrent disc herniation

We report a case of a 39-year-old male with sciatica who underwent an L5/S1 microdiscectomy with objective physical activity measurements performed preoperatively and continually postoperatively up to 3-month using wireless accelerometer technology linked to the surgical practice; collecting distance travelled, daily step count (DSC) and Gait Velocity (GV). Preoperative, the patient was walking with a GV of 0.97 m/s and a DSC of less than 2,500. After the first month following surgery, the patient had increased mobility, with a GV of 1.58 m/s, and taking an average of over 4,500 steps per day. At day 57 postop, the patient experienced a recurrence of pain with reduction of GV, DSC and walking distance. Magnetic resonance imaging (MRI) was performed and revealed a recurrent disc herniation with further surgery on day 63, with a rapid return of function post 2^nd surgery. The use of wireless accelerometers is practical in obtaining objective physical activity measurements before and after lumbar microdiscectomy, and will assist the surgeon and rehabilitation provider to monitor outcomes, complications and assist in clinical decision making.

Spine Surgery Outcomes in Workers' Compensation Patients

Occupational spine injuries place a substantial burden on employees, employers, and the workers' compensation system. Both temporary and permanent spinal conditions contribute substantially to disability and lost wages. Numerous investigations have revealed that workers' compensation status is a negative risk factor for outcomes after spine injuries and spine surgery. However, positive patient outcomes and return to work are possible in spine-related workers' compensation cases with proper patient selection, appropriate surgical indications, and realistic postoperative expectations. Quality improvement measures aimed at optimizing outcomes and minimizing permanent disability are crucial to mitigating the burden of disability claims.

Influence of psychosocial distress in the results of elective lumbar spine surgery

BACKGROUND

Low back pain can be caused by several pathological entities and its perception can be altered by external factors, for example by some psychological and social factors. The objective of this study was to compare surgical outcomes in patients with or without psychosocial issues.

METHODS

Single center, retrospective and comparative study. Patients with indication to elective lumbar spine surgery were screened for some psychosocial factors. As a result of the screening, patients were divided in two groups: mild psychosocial issues (green group) or moderate psychosocial issues (yellow group). The groups were compared using the following variables: demographic and clinical history, depression (HAD-D), anxiety (HAD-A), pain levels [visual analogue scale (VAS)], disability [Oswestry disability index (ODI)] and quality of life [EuroQol 5D (EQ-5D)] at preop and 6-12 months follow-up.

RESULTS

A total of 136 patients were included (51% female) in this study. The 62.5% were allocated at the green group, and 37.5% in the yellow group. Similar pain levels were observed at preop, but the green group evolved with superior improvement in pain levels after surgery (P=0.003). In the ODI and EQ-5D scales, the green group had already shown lower clinical disability at preop (P=0.009 and P=0.003, respectively) and evolved with better outcomes at the final evaluation (P=0.049 and P=0.017). VAS, ODI and EQ-5D scores improved from baseline similarly in both groups.

CONCLUSIONS

Presurgical screening identify the presence of psychological distress. Psychosocial factors are correlated with poorer clinical outcomes, both in the baseline and after the surgery. Despite the differences between found, even patients with mild psychosocial impairment can experience clinical improvement with surgery.

Physical Activity Measured with Accelerometer and Self-Rated Disability in Lumbar Spine Surgery: A Prospective Study

STUDY DESIGN

Prospective observational study.

OBJECTIVE

Patient-based subjective ratings of symptoms and function have traditionally been used to gauge the success and extent of recovery following spine surgery. The main drawback of this type of assessment is the inherent subjectivity involved in patient scoring. We aimed to objectively measure functional outcome in patients having lumbar spine surgery using quantitative physical activity measurements derived from accelerometers.

METHODS

A prospective study of 30 patients undergoing spine surgery was conducted with subjective outcome scores (visual analog scale [VAS], Oswestry Disability Index [ODI] and Short Form 12 [SF-12]) recorded; patients were given a Fitbit accelerometer (Fitbit Inc., San Francisco, California, United States) at least 7 days in advance of surgery to record physical activity (step count, distance traveled, calories burned) per day. Following surgery, postoperative activity levels were reported at 1-, 2-, and 3-month follow-up.

RESULTS

Of the 28 compliant patients who completed the full trial period, mean steps taken per day increased 58.2% (p = 0.008) and mean distance traveled per day increased 63% (p = 0.0004) at 3-month follow-up. Significant improvements were noted for mean changes in VAS back pain, VAS leg pain, ODI, and SF-12 Physical Component Summary (PCS) scores. There was no significant correlation between the improvement in steps or distance traveled per day with improvements in VAS back or leg pain, ODI, or PCS scores at follow-up.

CONCLUSIONS

High compliance and statistically significant improvement in physical activity were demonstrated in patients who had lumbar decompression and lumbar fusion. There was no significant correlation between improvements in subjective clinical outcome scores with changes in physical activity measurements at follow-up. Limitations of the present study include its small sample size, and the validity of objective physical activity measurements should be assessed in future larger, prospective studies.

Long-Term Objective Physical Activity Measurements using a Wireless Accelerometer Following Minimally Invasive Transforaminal Interbody Fusion Surgery

We report on a case of a patient who underwent minimally invasive transforaminal lumbar interbody fusion (mi-TLIF) with objective physical activity measurements performed preoperatively and postoperatively at up to 12-months using wireless accelerometer technology. In the first postoperative month following surgery, the patient had reduced mobility, taking 2,397 steps over a distance of 1.8 km per day. However, the number of steps taken and distance travelled per day had returned to baseline levels by the second postoperative month. At one-year follow-up, the patient averaged 5,095 steps per day in the month over a distance of 3.8 km; this was a 60% improvement in both steps taken and distance travelled compared to the preoperative status. The use of wireless accelerometers is feasible in obtaining objective physical activity measurements before and after lumbar interbody fusion and may be applicable to other related spinal surgeries as well.

The Effect of Workers' Compensation Status on Outcomes of Cervical Disc Arthroplasty: A Prospective, Comparative, Observational Study

BACKGROUND

Receiving Workers' Compensation benefits has been associated with inferior outcomes after lumbar fusion. The purpose of our study was to compare the outcomes of cervical disc arthroplasty between patients receiving and those not receiving Workers' Compensation.

METHODS

Patient-reported outcomes, reoperations, complications, and return-to-work status were analyzed at one year after surgery in an observational cohort of consecutive patients who underwent single-level or multilevel cervical disc arthroplasty for symptomatic cervical disc conditions, including radiculopathy or discogenic pain with or without radiculopathy, exclusive of myelopathy.

RESULTS

Of the 189 patients who underwent cervical disc arthroplasty, 144 received Workers' Compensation and forty-five did not. The mean scores on all patient-reported measures improved significantly from preoperative baseline to one year after surgery (p < 0.001), and the improvement in patient-reported outcomes did not differ significantly between the Workers' Compensation and the non-Workers' Compensation group (respectively, 22.7 compared with 25.0 for the Neck Disability Index; 8.3 compared with 9.6 for the Short Form (SF)-36 physical component summary; 7.9 compared with 9.6 for the SF-36 mental component summary; 3.5 compared with 3.7 for neck pain; and 2.6 compared with 2.8 for arm pain). The two groups also did not differ significantly in the rate of reoperations (7.6% for those receiving Workers' Compensation compared with 13.3% for those not receiving Workers' Compensation) and complications (2.8% compared with 4.4%, respectively). At one year after surgery, the proportion of patients who had returned to work was comparable (77.7% in the Workers' Compensation group and 79.4% in the non-Workers' Compensation group); however, the patients receiving Workers' Compensation had significantly more days off before returning to work (a mean of 145.2 compared with 61.9 days; p = 0.001).

CONCLUSIONS

After cervical disc arthroplasty, patients receiving Workers' Compensation had outcomes that were similar to those of patients not receiving Workers' Compensation in terms of patient-reported outcomes, surgery-related complications, reoperations, and return-to-work status. Patients receiving Workers' Compensation remained off work for a longer interval than did patients not receiving Workers' Compensation.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Association between compensation status and outcomes in spine surgery: a meta-analysis of 31 studies

BACKGROUND CONTEXT

Numerous studies have demonstrated poorer outcomes in patients with Workers' compensation (WC) when compared with those without WC following treatment of various of health conditions, including spine disorders. It is thus important to consider compensation status when assessing treatment outcomes in spine surgery. However, reported strengths of association have varied significantly (1.31-7.22).

PURPOSE

The objective of this study was to evaluate the association of unsatisfactory outcomes on compensation status in spine surgery patients.

STUDY DESIGN/SETTING

A meta-analysis was performed.

PATIENT SAMPLE

Patient sample is not applicable in this study.

OUTCOME MEASURE

Demographics, type of surgery, country, follow-up time, patient satisfaction, return to work and non-union events were the outcome measures.

METHODS

Both prospective and retrospective studies that compared outcomes between compensated and non-compensated patients in spine surgery were included. Two independent investigators extracted outcome data. The meta-analysis was performed using Revman software. Random effects model was used to calculate risk ratio (RR, 95% confidence interval [CI]) for dichotomous variables.

RESULTS

Thirty-one studies (13 prospective; 18 retrospective) with a total of 3,567 patients were included in the analysis. Follow-up time varied from 4 months to 10 years. Twelve studies involved only decompression; the rest were fusion. Overall RR of an unsatisfactory outcome was 2.12 [1.74, 2.58; p<.001] in patients with WC when compared with those without WC after surgery. The RR of an unsatisfactory outcome in patients with WC, compared with those without, was 2.09 [1.38, 3.17]; p<.01 among studies from Europe and Australia, and 2.14 [1.48, 2.60]; p<.01 among US studies. The RR of decompression-only procedures was 2.53 [1.85, 3.47]; p<.01,and 1.79 [1.45, 2.21]; p<.01 for fusion. Forty-three percent (209 of 491) of patients with WC did not return to work versus 17% (214 of 1250) of those without WC (RR 2.07 [1.43, 2.98]; p<.001). Twenty-five percent (74 of 292) and 13.5% (39 of 287) of patients had non-union in the compensated and non-compensated groups, respectively. This was not statistically significant (RR 1.33 [0.92, 1.91]; p=.07).

CONCLUSIONS

Workers' compensation patients have a two-fold increased risk of an unsatisfactory outcome compared with non-compensated patients after surgery. This association was consistent when studies were grouped by country or procedure. Compensation status must be considered in all surgical intervention studies.

Application for disability pension and change in use of prescribed drugs. A regional Danish cohort study

AIM

To investigate if a pending application for disability pension had an influence on the applicant's purchase of medical drugs, with a particular focus on musculoskeletal disorders and the use of painkillers.

METHODS

We performed a registry-based follow-up study including 12,020 applicants for disability pension in a Danish county from 1995 to 2000 and linked this information to a database of drug prescriptions. Purchase of drug was calculated for the 6-month period just before the decision and for the 6-month period 2 years later. Changes in a 2-year time period were estimated by differences in purchase rates. Furthermore, the proportion of applicants with an increased purchase of drugs and the proportion of applicants who ceased buying drugs were estimated. The results were stratified by diagnosis and result of application (awarded/rejected). The analyses were furthermore restricted to musculoskeletal disorders and the use of painkillers.

RESULTS AND CONCLUSIONS

At baseline 81% had a purchase and after the 2-year time period 11% ceased buying prescribed drugs. Half of all applicants increased the purchase of drugs. For musculoskeletal disorders one third had an increased purchase rate of painkillers while one fourth ceased purchase of drugs with variations in different diagnostic subgroups. The major changes of drug purchase after a pending application for disability pension are probably ascribed to characteristics of the diseases underlying the disability.

Predictors of outcome after anterior cervical discectomy and fusion: a multivariate analysis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Perform a multivariate analysis to identify important predictors of poor outcome following anterior cervical discectomy and fusion.

SUMMARY OF BACKGROUND DATA

Identifying prognostic factors is important to aid surgical decision-making and counseling of patients. Recent randomized control trials of disc arthroplasty devices have established a large cohort of patients treated with fusion and 2-year outcomes that allow analysis of prognostic factors.

METHODS

The patient cohort was the fusion control patients (n = 488) from 2 randomized controlled studies of disc replacements. Surgical indications were recalcitrant single-level subaxial radiculopathy or myelopathy. The surgery included anterior discectomy and fusion with allograft and plate. Patients were assessed by neck and arm pain, neck disability index (NDI), SF-36, neurologic examination, and return to work. Overall clinical success was defined based on meeting all 4 of these criteria: >15-point improvement in NDI; maintained or improved neurologic examination; no serious adverse event related to the procedure; and no revision of the plate or graft. Patient's outcomes were recorded, at 3, 6, 12, and 24 months, with 77% follow-up at 24 months.The outcome variables for this analysis were overall clinical success and >15-point improvement in NDI. We studied the relationship between each of the outcome variables and 26 potential important variables including demographics, medical conditions, socioeconomic factors, and disease state. Two statistical models were used to explore the association between outcome variables and baseline measures: multivariate logistical regression of the full model with every prognostic variable included and the model with the variables selected by the stepwise selection procedure.

RESULTS

In the full-model logistic analysis for overall success, worker's compensation and weak narcotic use were negative predictors while higher preoperative NDI score and normal sensory function were positive predictors. For NDI success, only the preoperative NDI scores (higher disability predictive of improvement) appeared to have strong influence on the outcome.In the stepwise regression model, preoperative normal sensory function was a positive predictor and worker's compensation a negative predictors of overall clinical success. Greater age, higher preoperative NDI score, and gainful employment were positive predictors and spinal litigation was a negative predictor of NDI success.

CONCLUSION

We found that important predictors of outcome were work status, sensory function, involvement in litigation, and higher disability scores.

CERVICAL DISC ARTHROPLASTY COMPARED WITH FUSION IN A WORKERS' COMPENSATION POPULATION

OBJECTIVE

Patients with cervical radiculopathy and/or myelopathy are often treated with anterior cervical discectomy and fusion. Cervical arthroplasty has recently been advocated as an alternative treatment. Theoretically, arthroplasty should permit early return to activity and protect against adjacent segment disease. Early mobilization and return to activity may, theoretically, reduce cost to the workers' compensation program.

METHODS

A subgroup analysis of workers' compensation patients from the randomized controlled trials comparing Prestige ST and Bryan (Medtronic Sofamor Danek, Memphis, TN) cervical arthroplasty to fusion was performed. Primary outcome measures were work status, time to return to work, and neck disability. Secondary outcome measures were neck and arm pain and Medical Outcomes Study Short-Form 36-Item Health Survey score.

RESULTS

One thousand four patients were enrolled in the studies, 93 of whom were workers' compensation patients. At 6 weeks and 3 months, significantly more patients in the arthroplasty group were working compared with the fusion group. At 6 months and later, there was no significant difference in return-to-work rates. Overall, patients returned to work at a median of 101 days after arthroplasty, compared with 222 days after anterior cervical discectomy and fusion. This difference was not significant when controlling for sex, study, and preoperative work status. At all time points, the Neck Disability Index was consistently lower in the arthroplasty group compared with the fusion group; however, the difference was not significant at 24 months. There was no statistically significant difference in secondary outcomes, neurological events, or pain-related events.

CONCLUSION

In this workers' compensation cohort, it was observed that a greater number of patients in the arthroplasty group returned to work at 6 weeks and 3 months after surgery. A trend toward an earlier return to work was also seen, although this was not statistically significant when controlling for differences in the studies.

Correlation of Short Form-36 and disability status with outcomes of arthroscopic acetabular labral debridement

BACKGROUND

Arthroscopic debridement is the standard of care for the treatment of acetabular labral tears. The Short Form-36 has not been used to measure hip arthroscopy outcomes, and the impact of disability status on hip arthroscopy outcomes has not been reported.

HYPOTHESIS

Short Form-36 subscale scores will demonstrate good correlation with the modified Harris hip score, but patients undergoing disability evaluation will have significantly worse outcome scores.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The records of active-duty soldiers who underwent hip arthroscopy at the authors' institution were retrospectively reviewed. Forty consecutive patients who underwent hip arthroscopy for the primary indication of labral tear formed the basis of the study group. Patients completed the modified Harris hip score, the Short Form-36 general health survey, and a subjective overall satisfaction questionnaire.

RESULTS

Thirty-three patients, with a mean age of 34.6 years, were available for follow-up at a mean of 25.7 months postoperatively. Fourteen (43%) patients were undergoing medical evaluation boards (military equivalent of workers' compensation or disability claim). Pearson correlation coefficients for comparing the Short Form-36 Bodily Pain, Physical Function, and Physical Component subscale scores to the modified Harris hip score were 0.73, 0.71, and 0.85, respectively (P < .001). The mean modified Harris hip score was significantly lower in patients on disability status than in those who were not (92.4 vs 61.1; P < .0001). The Short Form-36 subscale scores were significantly lower in disability patients (P < .02). Patient-reported satisfaction rates (70% overall) were 50% for those undergoing disability evaluations and 84% for those who were not (P < .04). There was no significant difference in outcomes based on patient age, surgically proven chondromalacia, or gender for military evaluation board status.

CONCLUSION

The Short Form-36 demonstrated good correlation with the modified Harris hip score for measuring outcomes after arthroscopic partial limbectomy. Arthroscopic debridement yielded a high percentage of good results when patients undergoing disability evaluations were excluded. Disability status may be a negative predictor of success after hip arthroscopy.

Bilateral implantation of low-profile interbody fusion cages: subsidence, lordosis, and fusion analysis

BACKGROUND CONTEXT

The use of interbody fusion cages as a treatment for degenerative disc disease has become widespread. Low-profile cages have been developed to allow a closer fit when implanting bilateral cages in patients with smaller vertebral bodies. Some surgeons feel the open design also allows better bone contact and visualization. This is particularly true when two low-profile cages are used adjacent to one another. Because of the open design of low-profile interbody fusion cages, there has been concern regarding such issues as subsidence, lordosis and fusion rates.

PURPOSE

This retrospective review of paired bilateral reduced profile interbody fusion cages was completed to assess changes in subsidence, lordosis and fusion. As a secondary goal, patient outcomes were measured to determine overall health since surgery and the patient's satisfaction with the spine surgery, in an attempt to assess the effect of the outcome variables cited supra.

STUDY DESIGN

This was a retrospective evaluation of patients who underwent anterior lumbar interbody fusion with low-profile interbody fusion cages.

PATIENT SAMPLE

Seventy-one consecutive patients who underwent bilateral implantation of low-profile interbody fusion cages were evaluated.

OUTCOME MEASURES

A patient self-evaluation, which included a Short Form (SF)-36 and questions regarding patient satisfaction were administered to patients who were at least 1 year postoperative. Subsidence and lordosis measurements were completed. Fusion was assessed by the operating surgeon.

METHODS

Low-profile interbody fusion cages (BAK/Proximity, Centerpulse Spine-Tech, Inc., Minneapolis, MN) were implanted bilaterally in at least one level from L3-L4 to L5-S1. Most patients had degenerative disc disease with leg and back pain that was not responsive to conservative treatment and demonstrated segmental instability or collapse. A small percentage of patients had either a degenerative spondylolisthesis (7.0%) or an isthmic spondylolisthesis (4.2%). Autograft harvested from the iliac crest was used in all cases. Demographic, surgical and follow-up data were retrospectively collected from patient charts. A clinical outcome questionnaire that included an SF-36 as well as questions regarding patient satisfaction was either mailed to each patient who was at least 1 year postsurgery or given to patients to complete at their 1-year visit. Patients were routinely followed radiographically before surgery, immediately after surgery and at 3, 6, 12 and 24 months after surgery. Fusion was assessed by the operating surgeon using lateral radiographs often in conjunction with a thin-slice computed tomography (CT) scan. Criteria for a successful fusion were lack of motion, anterior bridging bone and lack of lucencies on flexion/extension X-rays and/or contiguous bone through the cage using a thin-cut sagittal CT scan. Lateral X-rays on each patient were also measured for subsidence and lordosis changes.

RESULTS

A total of 71 patients (45 men, 26 women) with a mean age of 43.4 years (range, 25 to 74) were evaluated. Thirty-six percent of the patients were smokers, and 96% were worker's compensation patients. Thirty-two percent of the patients had previous lumbar surgery. A total of 100 operative levels were evaluated. There were 45 one-level, 23 two-level and three three-level cases. Forty-nine percent were level L5-S1, 43% were L4-L5 and 8% were L3-L4. The mean duration of symptoms was 31.5 months. Mean surgical time, mean blood loss and mean hospital stay were 139 minutes, 186 cc and 3.34 days, respectively. There were no intraoperative or postoperative complications attributable to the construct and no cases of cage migration or collapse. Patients who were at least 1-year postsurgery and had follow-up X-rays or had undergone a CT scan at this time point were evaluated for fusion status. Sixty-three patients were assessed for fusion. Fifty-four (86%) of these patients were determined to have a solid fusion. Mean time to fusion was 10 months. Fusion was assessed as solid only if all operative levels were fully fused. Mean subsidence of the anterior region was 1.97 mm, whereas the mean subsidence of the posterior region was 0.82 mm. Lordosis was unchanged at all surgical levels with mean lordosis in L3-L4 decreasing only slightly from 13 degrees before surgery to 12 degrees after surgery. L4-L5 and L5-S1 showed only slight increases in lordosis changing from 17 to 18 degrees at L4-L5 and from 17 to 19 degrees at L5-S1. These changes were not statistically significant. The clinical outcome questionnaires had a return rate of 68%. Of the 48 patients who completed the questionnaire, 75% responded that they were happy with the surgical results and would definitely recommend the surgery to a friend. Sixty-seven percent agreed that surgery met their expectations or that surgery improved their condition enough that they would go through it again for the same outcome. The results of the SF-36 portion of the survey revealed that the physical and mental composite scores were within normal range of the US population that has experienced back pain or sciatica.

CONCLUSION

Bilateral implantation of low-profile cages in this patient population led to satisfactory outcomes. Subsidence and changes in lordosis were minimal. Fusion rates were good, especially for one-level cases. Patient satisfaction was relatively high, considering the population consisted of 96% worker's compensation cases. With proper surgical technique, bilateral low-profile cages can be used effectively to treat patients with degenerative disc disease.