Introduction

Spondylolisthesis is a disease of mankind in which original description was of lyric listhesis ,later degenerative was described .it is classified based on etiology into 5 types: congenital or dysplastic, isthmic, degenerative, traumatic, and pathologic (Wiltse, 1976)¹⁴In 1854, Killian coined the term spondylolisthesis to describe the gradual slippage of the L5 vertebra due to gravity and posture⁷. The incidence of isthmic type of spondylolisthesis is believed to be approximately 5% based on autopsy studies. Degenerative spondylolisthesis is observed more frequently as the population ages and occurs most frequently at the L4-L5 level. Up to 5.8% of men and 9.1% of women are believed to have this type of listhesis.The etiology of spondylolisthesis is multifactorial.^14,12,9 Spondylolisthesis can be graded based on the amount of vertebral subluxation in the sagittal plane, as adapted from Meyerding(1932)⁷: Grade 1 - Less than 25% of vertebral diameter Grade 2 - 25-50% Grade 3 - 50-75% Grade 4 - 75-100% Spondyloptosis - Greater than 100%

Posterior Lumbar interbody fusion:PLIF is a procedure that has enjoyed popularity over past 50 years. Ralph Cloward pioneered it in 1940.Recent advances in spinal instrumentation and minimal access techniques have revitalized interest in PLIF. The indications of PLIF and variants of it as TLIF have expanded and include numerous pathologies. A surgical technique of PLIF with the use of autogenously posterior elements cut into 2-4 mm as graft material has distinct advantages.⁸ James Walter, Simmons et al studied about 113 patients treated between 1974-1980 and noted good objective results as high as 79%.Chip PLIF appears to decrease the morbidity associated with taking autogenously bone from the other sites.^.They preferred to use corticocancellous chips which would allow far more bone to be put into the intervertebral disc space and provide less dead space for the fibrous tissue. Anie F ,Mannion MD et al ¹ studied the importance of neurogenic claudication in the diagnosis of spondylolisthesis and as such assessed the pain in these patients. The importance of pain was highlighted in 1990’s when the American Pain Society declared it as the fifth vital sign of medical examination. Interbody fusion being near the centre of axis of rotation close to the weight being bearing column has fusion rates of 97% in many series

Material And Methods

In the present study all patients were asked history and subjected to thorough clinical examination.The preoperative VAS and ODI scores were noted down.The preoperative dynamic x-rays were taken [fig 3]] and the Disc Heights[fig 2,Fig 3] ,

Figure 1

Fig1;Measuring grade

Figure 2

Fig 2 Measure Disc height

Meyerding grade[fig 1] and the slip angles were measured.

Patients written and informed consent was taken. All the investigations relevant from the point of view of anaesthesia were done and the Pre-Anaesthetic clearance was taken.After proper written consent patients were taken then for the said surgical procedure.

Operative technique :After satisfactory induction of anaesthesia,the patient was positioned prone on a four-poster frame ^{and all pressure points were well padded.}

Fig 3-4 Laminectomy & decompression

Figure 3

Figure 3

Figure 4

Figure 4

A standard midline posterior approach was used to expose the spine as per the level of involvement. Laminectomy and decompression was done[Fig 3] to [Fig 4] ^{The spinous processes and the laminae were made into chip grafts. Total discectomy was performed at the degenerated level. The level involved was fixed using transpedicular monoaxial /polyaxial screws with reduction screws put into the listhesed vertebra}

Fig 5-6 Instrumentation stages

Figure 5

Figure 5

Figure 6

Figure 6

The interbody spacer was placed[Fig 6] and the reduction maneuver performed by lifting the upper body in a cranial and posterior direction.The screws were connected with rods and disc space gradually distracted to achieve lordosis along with the good reduction. The final construct was tightened in compression. After completion of the discectomy and the transfixation, cancellous bone chip grafts were used as interbody graft and well packed snugly into the level for an interbody fusion in group II while cages were put into Group I patients. We did not perform any SSEP during the procedure. Haemostasis was achieved and wound was closed in layers over a suction drain .Patient was subjected to X-ray L/S spine AP & Lateral views on first postoperative day [Fig 7 and Fig 8]and the various measurements were again taken for comparison.

Immediate post-op x-rays

Figure 7

Fig 7 [LAT]

Figure 8

fig 8[AP]

After surgery patients were braced in LSO for a period of 3 months for comfort.Patient was discharged on third post operative day and advised to follow the OPD on tenth day for removal of stitches and subsequently to every month for about 24months. Fusion was assessed by Lumbosacral X-rays

Figure 9

Fig 9 fusion [graft group] Fig 10 ;Fusion [Cage Group]

The total operative time averaged 3.2 hours (Range 2-5hrs).The estimated blood loss was 200ml (Range 100-350 ml).

Results

Among (n=28) patients,71.5%(n=19) were females and 28.5%(n=9) were males.71.5%(n=18) were having L4/L5 and 28.5%(n=10) L5/S1 spondylolisthesis.42.9%(n=11) were of grade I and 57.1%(n=17) were of grade II spondylolisthesis

Following were our observations.

Figure 10

Gender out of total 28 cases 19 were females while 9 were males

Figure 11

No of patients as per level involvement

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

We used spinous process chip grafts in 15 patients and cage in 13 patients. This is comparable with⁸ in which though the number of patients was more, also the spinous processes were used as chip grafts and fusion was assessed. We observed a mean change in disc height of 1.2mm+_S.D in the graft group and 2mm+_ S.D in the cage group of patients.This is comparable with the research project of P.gopinathan et al¹¹ in which the mean change in disc height was 4mm. The mean change in VAS score in graft group was 5(62%) in graft group and that in the cage group was 7.2(88%).This is comparable with the research work of P.Gopinathan et al ¹¹ in which 2 points better VAS score improvement than ours was seen. In both the two groups the mean improvement in slip angles was about 3.2deg+_ S.D. In this series we noted complications in about 4 patients with implant loosening in 1(3.5%) of patients[Fig 11],pedicle wall breakage in 1(3.5%) and wound infection (MRSA) in 1(3.5%) patient[Fig 12].One patient with implant loosening and another with pedicle wall breakage was reoperated.

Figure 17

Fig 11 Implant loosening

Figure 18

fig 12 superficial infection[MRSA]

One patient with implant loosening is having mild backache on movement with improvement in VAS from 9 to 4.She is waiting for the implant removal. One patient with wound infection was managed with superifical wound debridement and her cultures showed MRSA positivity for which she was treated .

There was a statistically significant correlation (p<0.012 and p<0.027) between the increment in disc height we achieved and the improvement in VAS score in both graft group and cage group. The increment in disc height and VAS score were significantly better in Cage group(2mm+- S.D visa-viz 7.2(88%) ) than the graft group(1.2mm+- S.D visa-viz 5(62%) .

Discussion

It is well known fact that weight transmission is the sole culprit for the progression of listhesis. Disc space height maintenance Indicates total discectomy .As a result it, Increases neural foramina height, thus larger the height ,stronger graft (volume) can be inserted .

In our study we operated 28 patients in the age group of 30-70years.out of which ,6 patients(21.42%) were in the age group of 30-40yrs,10(35.71%) of 40-50yrs,9(32.14%) of 50-60yrs and 3(10.71%) was in the age group of 60-70yrs. Among 28cases 19(67.85%) were females and 9(32.14%) were males. In this series 18(64.28%) were having involvement of L4L5 level while 10(35.71%) had involvement of L5S1 level. About 11(39.28%) were having grade I while 17patients(60.71%) had grade II spondylolisthesis. Out of The total 28 patients included in this study,all of them presented with LBA while 18(64.28%) had neurogenic claudication as the presenting symptom and 10(35.71%) patients had additional radiculopathy.Associated.Symptoms appeared at approx.1km distance in 9(32.14%),2km distance in 7(25%) and 3 km distance in 12(42.85%) patients..

Disc height restoration :

Conclusion

In this our series of twenty eight patients subjected to PLIF procedure it is concluded that maintenance of disc height with the help of Spacer Is preferred over graft. Using spinous processes avoids additional incision and graft site morbidity. Although a technically demanding procedure, PLIF procedure is a procedure of choice for the grade I,II and Grade III degenerative and isthmic spondylolisthesis.