Introduction

Obesity has emerged as a global major health problem in the last decades with subsequent multisystem drawbacks and adverse consequences on the populations and communities (4, 14, 21).Obesity is affecting more than300 million people in the world (7, 14) and is diagnosed when a body mass index is  ≥30Kg/M2 (20)

The impact of obesity on the spinal disorders involves low back pain, facet arthritis, and degenerative disc diseases (21, 25).

Lumbar discectomy for obese patients is challenging and is still debatable as there is no clear evidence of superiority of lumbar discectomy over the conservative(3, 8).

Treatment of symptomatic lumbar disc prolapse in obese patients usually has refractory symptoms even with maximum medical treatment and physiotherapy, whereas surgical intervention   is associated with higher surgical risk and complications (4).

Materials and Methods

Disability has been prospectively evaluated in 172 patients, 93 male and 79 female who have been treated by lumbar discectomy due to refractory symptomatic lumbar disc prolapse between July 2010 and July 2013.

Patients were divided in to 4 groups according to the body mass index (BMI) (8) into; Normal weight (18.5–24.99), overweight (25–29.99), obesity (>30-34.99) and morbid obesity (BMI ≥35).

All patients   were evaluated clinically and the diagnosis was confirmed by MRI study.

 The Disability and functional status have been evaluated using The Oswestry Disability Index (ODI) (6) and prolo economic outcome scale (24).

Patients with past history of spinal surgery, spinal instability, and chronic disease affect the patient recovery or functional status was excluded.

In this study   Data were entered checked and analyzed using SPSS for Windows version 11.5  and office excel version 2010 .We used descriptive statistics, comparing means and correlation studies to analyze the results .For all statistical tests the threshold of significance is fixed at 5% level.

Study groups and patient criteria were summarized in Table (1).

Table 1

The patient criteria

Results

The mean age of patients in this study is 36.24±8.9 years old ranging between 21 and 59 years .out of the 172 patients 93 were male and 79 were female. Most of them (75.6%) have abnormal body weight and only 24.4% has normal body weight.  45.9% of the patients have over weight, obesity   was found in 21.5% and morbid obesity represented 8.1% of the patients.

Male predominance is detected in our study groups except in morbid obese patients as it represented 59.5%, 54.4% and 56.8% in normal weight, overweight and obese patients respectively while it represented only 28.6% of the patients with morbid obesity.

Preoperative Clinical assessment and disability evaluation of the patient revealed significant   higher disability index    in the morbid obese patients than other groups.

Figure 1

patient improvement after surgical treatment

Preoperative radiological assessment revealed  increased  multiplicity of the prolapsed disc levels with the increase in the BMI as the mean  number of involved disc levels is 1.29 in  the  patients with  normal  weight  while it  increase gradually  with the increase in the body  weight.

Table 2

Preoperative and post-operative ODI

The  mean ODI  at the end point of the study   is 34.12±15.4  with  mean improvement  23.6±15  with     significant  improvement    in the first  three groups  (figure 2a.2b and 2c) but   in  patient with morbid obesity the mean improvement  is only  7.3±18  as shown in .

At  the end point  of the study  clinical    improvement  have been detected in  78.6% , 77.2%  and 97.3%  for  the patient  with normal  weight , overweight  and obese patient  respectively  while it  was only  28.6% in patient  with morbid obesity.

Table 3

Improvement after surgical treatment

At the end point of the study prolo  economic scale which  reflect the functional recovery and work  status is 4.79, 4.39 and 4.73 in  patient  with  normal weight, overweight  and  obese patient   respectively  while it is only 2±1.1 in patient  with  morbid obesity.

Table 4

Preoperative and post-operative prolo Economic scale

Figure 2a

Preoperative and post-operative ODI in patient with normal weight P value (0.001)

Figure 2b

Preoperative and post-operative ODI in patient with overweight weightP value (0.03)

Figure 2c

Preoperative and post-operative ODI in patient with obesity P value (0.009)

Figure 2d

Preoperative and post-operative ODI in patient with morbid obesityP value (0.97)

Figure 3

Preoperative and post-operative prolo scale A: in patient with normal body weight, B: in patient with overweight, C: in Obese patients and D: in patient with morbid obesity

Discussion

Obesity is becomes global health problem affecting more than 300 million person in the world (7, 14) involving not only the developed countries but also Asian and developing countries (2).

Obesity is associated with adverse consequences and multiple health problems (23).The impact of obesity on the spinal disorders involves low back pain, facet arthritis, and degenerative disc diseases (21, 25) because body weight in obese patient lead to mechanical stress on the spine and disturbance in the biomechanics of the spine while the excess adipose tissues produces cytokines which activate biochemical changes in the discs, joints and ligaments of the spine (18).

The problem of obesity and its effect  on the spinal disorders was detected in our community  as  in this  study   most  of   patients  has abnormal  body  weight where  overweight , obesity   and  morbid obesity  were  representing 45.9%,21.5%,8.1% of the patients respectively.

Management of lumbar disc prolapse in obese patient is challenging and still debatable although it is well known that obese patient has worse outcome than non-obese in both operative and conservative treatment (25) but there is no clear   evidence of superiority of lumbar discectomy over the conservative treatment in those patients.

Gender do not affect the presence or the extent of the lumbar disc  diseases (26),however in our  study males with  symptomatic  lumbar  disc prolapse  is more common  than females (54%)and (46%)respectively which   is in agreement  with  Silverplats and his colleagues (22)who reported 56% male and 44% female in their  study.

  Obesity  is more common in females than males  due to  biological  and  socioeconomic factors(13) but  this was  found  only  in our  morbid obese group in which  female represented  71.4%  of the patients  while   male  were more  common than females in other  groups .

 The upper age limit affecting the outcome after lumbar surgery was considered above 45 years (5,12)but Scott and Harrison(23) found that there is no adverse effect on the outcome above 45 years and the mean age of the patients in our  study  is 36.24±8.9 without  significant  difference  between the first  three groups which is 34.2±11.1, 35.7±7.5 and 35.8±7.1 respectively but there is significant  higher  mean age in  morbid obese patients  (46±8.1).

The radiological changes in the intervertebral lumbar disc  was detected   in  patients with  abnormal body  weights  while  Persistent overweight  is associated strongly with an increased risk of the numbers of lumbar discs (17,21) and in this study  Single disc disease have been noticed in 70% of patient  with  normal   body  weight   while the multiplicity  of disc diseases have been noticed   in obese patients.

The severity  of symptoms  in   lumbar disc diseases  can  be affected by  the patient’s  pain threshold , psychological status ,Gender ,age ,degree of compression, number of affected discs and duration of compression .

Nerve root compression due to lumbar disc prolapse is increasing by obesity (16) but in our   study this effect did not appear except in the morbid obese patients  as the mean  Oswestry disability index (ODI) at presentation was 59.4,56.5 and 52.5  respectively without  significant  difference  while the it was  70.8 in  morbid obese patients .

The primary outcome measures were significantly less for obese patient in both operative and non-operative groups (25) yet the lumbar discectomy in obese patient   is still debatable and challenging.

In this  study Patient   improvement have been  achieved  in  78.6% , 77.2%  and 97.3%  for  the patient  with normal  weight , overweight  and obese patient  respectively  while it  was only  28.6% in patient  with morbid obesity and although the mean ODI at the end point of the study   is 34.12±15.4  with  mean improvement  23.6±15 , the  change in the ODI  between the preoperative measurement  and the  final  ODI  in morbid obese patient   is only 7.3±18.

 Multiple studies have assessed the effect of obesity on outcomes of lumbar surgery but with contradicting findings. Furukawa et al (9), LaCaille (15) and Patel et al (20) reported negative effect of obesity on the outcome after surgery    and there was or increased complications rate in the SPORT study (21) while Andreshak et al (1) and Gepstein et al (11) reported little or no effect.

These contradictions in the results can be explained by the various prognostic factors, different spinal pathology and different outcome parameters between the studies.patients with morbid obesity are reluctant to start  the  early  ambulation   with  higher postoperative pain with  subsequent failure of postoperative rehabilitation    and  instead of  losing weight after spinal surgery, those patients  had gained weight with subsequent  no improvement in the daily  activities or returning  to  work (10).

Functional recovery and return to work in patient  with  spinal disorder is multifactorial  depending  on the nature of the job ,psychological factors and  work consumption  and  in our  study  the economic outcome scale revealed significant  improvement   in the first  three groups  but   surgery was associated with  negative  effect   in morbid obese patients.

Conclusion

There is no significant improvement in the functional status of the morbid obese patient  after  lumbar  discectomy   while  there is significant improvement  in  patient with overweight and obese patients after  lumbar  discectomy.