An experience of posterior spinal fusion procedures for degenerative spondolisthesis.

Khan AM, Levack B.

Department of Orthopaedics and Trauma, King George hospital, Essex

Aim:

(1) to assess the results of decompression instrumentation and posterior spinal fusion for degenerative spondolisthesis. (2) to establish if these procedures can be performed safely, with good results in a district general hospital.

Method:

40 consecutive patients were included in this study. All underwent decompression and posterior spinal fusion for degenerative spondolisthesis. The average age was 48 years (range of 24-72 years) with a mean follow up of 3.7 years (range of 1-10 years). 31 patients had Pedicle screw fixation and 9 patients had Hartshill fixation. Patients were assessed by their clinical follow up (operative and postoperative complication), radiographic analysis and postal questionnaires. 33 patients (8 Hartshill, 25 Pedicle screw) replied to the questionnaires.

Results:

The overall fusion was 87.5%. A total clinical complication rate of 20% was noted (Hartshill rectangle 2.5%, Pedicle screw 17.5%) and 12% of the patients were not satisfied with the overall outcome (Pedicle screw fixation 3%, Hartshill rectangle 9%). Hartshill procedure had less clinical complications but Pedicle screw had better postoperative patient satisfaction and pain control, better mobility and sleep, less analgesia use and improved quality of life.

Conclusions:

We conclude that though both techniques had good radiological fusion, however Pedicle screw is a difficult surgical technique and has a possibility of more complications but achieves better patient’s satisfaction and can be safely performed in a district general hospital.

Degenerative spondolisthesis is slippage of one vertebral body on another. This is mostly associated with chronic low back pain. Women are more affected then men. L4-L5 is the common site affected.

Indication for surgical intervention is failure of conservative treatment and progression of disease. The choice of procedure is debatable. Studies have shown reasonable outcome with decompression alone (1), but further vertebral slippage is always a possibility (2,3). Most advocate spinal arthrodesis to prevent spinal instability and vertebral slippage (4,5).

Randomised prospective study by Fischgrund et al (6) compared decompression and fusion with and without the use of instrumentation. Two year follow up showed an increase in fusion in the instrumented group but there was no advantage in clinical outcome.

Fusion options are floating fusion (1), Posterior inter-transverse fusion (2), Anterior and Posterior instrumentation fusion alone or combined (7-10).

Our study shows patient’s outcome with decompression and spinal fusion with two surgical procedures. Pedicle screw instrumentation is now the more widely performed surgical technique and Hartshill rectangle, the less favourable procedure. Several different aspects are looked at to see the overall results of the success of spinal fusion in our study group.

Patients in this study are included from December 1989 - February 1999. 40 patients found and all were included in this study. 3 different questionnaires were designed, a clinical review, radiographic and a Patients questionnaires (see table).

There were 14 (35%) males and 26 (65%) females. The average age was 48 years ranging from 24 to 72 years. The study group were under the practise of two consultant orthopaedic surgeons. Every patient had a minimum of 1 year follow up in the clinics. The mean follow up was 3.7 years. 21 patients had had up to 3 visits in the followup clinics, remaining all had 4 or more visits in the clinics. 32 patients had up to at least 3 X-rays, remaining had more than 3 X-rays in the follow up clinics.

The most common site of deformity was L4-5 (22/40). Other sites were L5-S1 (13/40), L3-L4 (2/40) and 3 had L4-L5-S1. All 40 patients were treated with decompression, autogenous bone grafting and inter transverse spinal fusion. 9 patients had Hartshill rectangle instumentation whereas remaining 31 had Pedicle screw fixation.

11 patients had their operation within 6 months whereas remaining all had to wait more than 6 months.10 patients had to wait more than18 months.

All patients were X-rayed pre-operatively, immediately post operatively and at the time of the study. X-rays were evaluated for degree of spondolisthesis, disc height and degree of fusion, and pseudoarthrosis. For the purpose of the study fusion was defined as mature, visible bridging bone on x-rays. Progression of deformity was also recorded.

1. Clinical review and complications:

8 (20%) patients had some sort of operative or post-operative complication.

A total of 17.5% complications were recorded in the pedicle screw patients and these were: 2 cases of instrumentation failure (broken screws), 2 cases of superficial wound infection, 1 of deep wound infection and 2 cases of dural tears. There was 1 case of UTI recorded post operatively.

There was no case of instrumentation failure, deep wound infection, dural tears, UTI in the 9 Hartshill procedures. Only 1 case (2.5%) of superficial wound infection was recorded.

There were no cases of neurological defects, radiculopathy, recurrent stenosis, deep vein thrombosis and pulmonary embolism in any of the procedures.

2. Radiographic analysis:

Overall fusion was 87.5%. 27 (87%) cases out of total 31 showed complete fusion in the Pedicle screw fixation group, whereas 8 (88%) cases out of the total 9 had shown complete fusion in the Hartshill group.

1 case of pseudoarthrosis was recorded in pedicle screw, no case of worsening deformity was noted in either of the procedures.

3. Questionnaire outcome:

33 patients returned there questionnaire, 8/9 (88%) from H= Hartshill group and 25/31 (80%) from P= Pedicle screw patients returned their questionnaire.

Pain:

28 patients (6/8 from H group and 22/25 from P group) reported severe pain (8-10 score) before the operation, 10 (2/8 of H and 8/25 of P) in the following 6 months and 6 patients (n=3=from H group and n=3 of the total P group) had severe pain even after the operation. 3 of H and 14 of the P group had no to mild pain (0-4 score) at the time of the study.

Mobility and job:

18 patients (4/8 of H and 14/25 of P group) patients had mobility severely affected whereas after the operation 7 (3/8 and 4/25 of H and P group respectively) were affected now. An improvement score (0-4), H= 4 and P= 16 was recorded.

Similarly total of 4/8 of H and 14/25 of P group had had their job severely ( score 8-10) affected before the operation, 3/8 of H and 5/25 of P group had severe score after the operation.

Analgesia and sleep:

4/8 and 14/25 of the H and P group had shown no improvement with analgesia preoperatively whereas 4 patients (n=3 of H and n=1 of P group) are now on regular analgesia. 5 patients (3/8 of H and 2/25 of P group) are having their sleep effected now after the operation the remaining all have shown improvement.

Physiotherapy

18 patients (7/8 of the H group and 11/25 of the P group) had shown no improvement with regular physiotherapy before the operation whereas after the operation total of 9 patients 4/8 of the H and 5/25 of the P group did not thought that physiotherapy was helpful.

Quality of life

19 patients (5/8 of H and 14/25 of the P group) had poor quality of life (score 8-10) before surgery whereas 4 patients (1/8 of H and 3/25 of P group) had poor quality of life after the operation. 4 of H and 19 of P group had a quality of life good to mildly effected (1-4) score.

Overall satisfaction and would they have the procedure again:

5 and 22 patients of the H and P group were satisfied or moderately satisfied with the outcome. 4 patients (12%) were not satisfied with the overall outcome (n=3 of H and n=1 of P group).

6 (75%) of H and 23 (82%) of P group would be willing to have the same procedure again. 4 patients (2/8 of H and 2/25 of the P group) would not have the procedure again.

Hartshill rectangle has been successfully used as a method of fixation for various indications (11,12) and as a method of internal fixation in the lumbar spine (13) and fusion (14).

Booth et al (15) showed an effective 5-year outcome in pedicle screw with posterior spinal fusion. This view was further strengthened with other studies (16) and a meta analysis study (17), all showing good results with pedicle screw fixation.

Cresswell et al (18) found AO fixation to have a better outcome than Hartshill. No studies have yet been able to show an advantage of Pedicle screw over Hartshill rectangle. Cadaver studies (19) have shown Pedicle screw technique to be more stable to control movement in flexion, extension and rotation.

Assessment of success of a spinal operation is thought to be dependent on certain aspects e.g., fusion of spine, worsening spondolisthesis, and complications like pseudoarthrosis, neurological deficit and stenosis etc. Surgical results are also compared or analysed with patient’s satisfaction with the procedure.

The overall radiological fusion in our study is 87.5%. There were significantly less operative and postoperative complications seen with the Hartshill surgical technique probably because of the relative simplicity of the technique. On the other hand Pedicle screw is a difficult technique and requires considerable expertise and precision to be performed successfully. Though we have noted more surgical complications in our study it has been able to achieve a superior outcome in terms of functional criteria such as pain control, mobility, job effect, sleep, analgesia, quality of life and the overall satisfaction of patients.

We understand that our study group was retrospective, although we modified the patient questionnaire in an attempt to gain a prospective view by adding questions on functional criteria’s before the operation, 6 months after and at the time of the study. Similarly one can argue about the minimum 1-year follow-up time patients. Our study was able to show an improvement trend 6 months and at the time of the study, this demonstrates sufficient time to see the safety and effectiveness of the procedure in our study group.

The eventual outcome of the success or failure of a surgical technique is a balance of Clinical outcome, radiological results and the patients satisfaction to the overall procedure. All our results are comparable with the results of other published reports on surgical treatment of degenerative spondolisthesis (1,2,5,15,16). All fusion techniques require considerable expertise to be performed successfully. Our study shows they can be done with good results outside a non specialized unit and in a district general hospital, provided the essential skill and requisite support in theatres, wards and outpatients is available.

Conclusions:

We conclude that though both techniques had good radiological fusion, however Pedicle screw is a difficult surgical technique and has a possibility of more complications but achieves better patient’s satisfaction and should be the method of choice for treating degenerative spondolisthesis.

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