The December 2023 Spine Roundup. 360. looks at: Does size matter in adolescent pedicle screws?; Effect of lumbar fusion and pelvic fixation rigidity on hip joint stress: a finite element analysis; Utility of ultrasonography in the diagnosis of lumbar spondylolysis in adolescent patients; Rett syndrome-associated scoliosis a national picture

The development of spinal deformity in children with underlying neurodisability can affect their ability to function and impact on their quality of life, as well as compromise provision of nursing care. Patients with neuromuscular spinal deformity are among the most challenging due to the number and complexity of medical comorbidities that increase the risk for severe intraoperative or postoperative complications. A multidisciplinary approach is mandatory at every stage to ensure that all nonoperative measures have been applied, and that the treatment goals have been clearly defined and agreed with the family. This will involve input from multiple specialities, including allied healthcare professionals, such as physiotherapists and wheelchair services. Surgery should be considered when there is significant impact on the patients’ quality of life, which is usually due to poor sitting balance, back or costo-pelvic pain, respiratory complications, or problems with self-care and feeding. Meticulous preoperative assessment is required, along with careful consideration of the nature of the deformity and the problems that it is causing. Surgery can achieve good curve correction and results in high levels of satisfaction from the patients and their caregivers. Modern modular posterior instrumentation systems allow an effective deformity correction. However, the risks of surgery remain high, and involvement of the family at all stages of decision-making is required in order to balance the risks and anticipated gains of the procedure, and to select those patients who can mostly benefit from spinal correction.

Aims

Some patients presenting with hip pain and instability and underlying acetabular dysplasia (AD) do not experience resolution of symptoms after surgical management. Hip-spine syndrome is a possible underlying cause. We hypothesized that there is a higher frequency of radiological spine anomalies in patients with AD. We also assessed the relationship between radiological severity of AD and frequency of spine anomalies.

Aims

Although lumbosacral transitional vertebrae (LSTV) are well-documented, few large-scale studies have investigated thoracolumbar transitional vertebrae (TLTV) and spinal numerical variants. This study sought to establish the prevalence of numerical variants and to evaluate their relationship with clinical problems.

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The aim of this study is to test the hypothesis that three grades of sagittal compensation for standing posture (normal, compensated, and decompensated) correlate with health-related quality of life measurements (HRQOL).

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The aims of this study were to measure sagittal standing and sitting lumbar-pelvic-femoral alignment in patients before and following total hip arthroplasty (THA), and to consider what preoperative factors may influence a change in postoperative pelvic position.

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We present the results of correcting a double or triple curve adolescent idiopathic scoliosis using a convex segmental pedicle screw technique.

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Clinical and radiological data were reviewed for all patients with mucopolysaccharidoses (MPS) with thoracolumbar kyphosis managed non-operatively or operatively in our institution.

Aims. We reviewed 34 consecutive patients (18 female-16 male) with isthmic spondylolysis and grade I to II lumbosacral spondylolisthesis who underwent in situ posterolateral arthodesis between the L5 transverse processes and the sacral ala with the use of iliac crest autograft. Ten patients had an associated scoliosis which required surgical correction at a later stage only in two patients with idiopathic curves unrelated to the spondylolisthesis. . Methods. No patient underwent spinal decompression or instrumentation placement. Mean surgical time was 1.5 hours (1 to 1.8) and intra-operative blood loss 200 ml (150 to 340). There was one wound infection treated with antibiotics but no other complication. Radiological assessment included standing posteroanterior and lateral, Ferguson and lateral flexion/extension views, as well as CT scans. . Results. A solid posterolateral fusion was confirmed in all patients at mean latest follow-up of 4.7 years (3.4 to 9.8) beyond skeletal maturity into early adult life. Fusion of the isthmic lesion was documented in nine patients bilaterally and eight patients unilaterally. The poor fusion rate across the spondylolysis has not affected the excellent functional results of the procedure, which in our series depended on achieving a stable lumbosacral junction. . Conclusion. Quality of life assessment demonstrated significant improvement in all functional scores and high patient satisfaction with 28 patients returning to previous sports activities at an elite competitive level. Take home message: Posterolateral arthrodesis in situ with autologous iliac crest bone without instrumentation has achieved a solid fusion between the L5 transverse processes and the sacral ala in patients with grade I to II isthmic lumbosacral spondylolisthesis and this has produced excellent clinical outcomes and high patient satisfaction. Cite this article: Bone Joint J 2016;98-B:88–96

Back pain is a common symptom in children and adolescents. Here we review the important causes, of which defects and stress reactions of the pars interarticularis are the most common identifiable problems. More serious pathology, including malignancy and infection, needs to be excluded when there is associated systemic illness. Clinical evaluation and management may be difficult and always requires a thorough history and physical examination. Diagnostic imaging is obtained when symptoms are persistent or severe. Imaging is used to reassure the patient, relatives and carers, and to guide management.

Cite this article: Bone Joint J 2014;96-B:717–23.

We investigated the relationship between spinopelvic parameters and disc degeneration in young adult patients with spondylolytic spondylolisthesis. A total of 229 men with a mean age of 21 years (18 to 26) with spondylolytic spondylolisthesis were identified. All radiological measurements, including pelvic incidence, sacral slope, pelvic tilt, lumbar lordosis, sacral inclination, lumbosacral angle (LSA), and sacrofemoral distance, were calculated from standing lateral lumbosacral radiographs. The degree of intervertebral disc degeneration was classified using a modified Pfirrmann scale. We analysed the spinopelvic parameters according to disc level, degree of slip and disc degeneration.

There were significant positive correlations between the degree of slip and pelvic incidence (p = 0.009), sacral slope (p = 0.003) and lumbar lordosis (p = 0.010). The degree of slip and the LSA were correlated with disc degeneration (p < 0.001 and p = 0.003, respectively). There was also a significant difference between the degree of slip (p < 0.001) and LSA (p = 0.006) according to the segmental level of disc degeneration.

Cite this article: Bone Joint J 2013;95-B:1239–43.

Wrong-level surgery is a unique pitfall in spinal surgery and is part of the wider field of wrong-site surgery. Wrong-site surgery affects both patients and surgeons and has received much media attention. We performed this systematic review to determine the incidence and prevalence of wrong-level procedures in spinal surgery and to identify effective prevention strategies. We retrieved 12 studies reporting the incidence or prevalence of wrong-site surgery and that provided information about prevention strategies. Of these, ten studies were performed on patients undergoing lumbar spine surgery and two on patients undergoing lumbar, thoracic or cervical spine procedures. A higher frequency of wrong-level surgery in lumbar procedures than in cervical procedures was found. Only one study assessed preventative strategies for wrong-site surgery, demonstrating that current site-verification protocols did not prevent about one-third of the cases. The current literature does not provide a definitive estimate of the occurrence of wrong-site spinal surgery, and there is no published evidence to support the effectiveness of site-verification protocols. Further prevention strategies need to be developed to reduce the risk of wrong-site surgery.

This review of the literature presents the current understanding of Scheuermann’s kyphosis and investigates the controversies concerning conservative and surgical treatment. There is considerable debate regarding the pathogenesis, natural history and treatment of this condition. A benign prognosis with settling of symptoms and stabilisation of the deformity at skeletal maturity is expected in most patients. Observation and programmes of exercise are appropriate for mild, flexible, non-progressive deformities. Bracing is indicated for a moderate deformity which spans several levels and retains flexibility in motivated patients who have significant remaining spinal growth.

The loss of some correction after the completion of bracing with recurrent anterior vertebral wedging has been reported in approximately one-third of patients. Surgical correction with instrumented spinal fusion is indicated for a severe kyphosis which carries a risk of progression beyond the end of growth causing cosmetic deformity, back pain and neurological complications. There is no consensus on the effectiveness of different techniques and types of instrumentation. Techniques include posterior-only and combined anteroposterior spinal fusion with or without posterior osteotomies across the apex of the deformity. Current instrumented techniques include hybrid and all-pedicle screw constructs.

We describe the results of a prospective case series of patients with spondylolysis, evaluating a technique of direct stabilisation of the pars interarticularis with a construct that consists of a pair of pedicle screws connected by a U-shaped modular link passing beneath the spinous process. Tightening the link to the screws compresses bone graft in the defect in the pars, providing rigid intrasegmental fixation. We have carried out this procedure on 20 patients aged between nine and 21 years with a defect of the pars at L5, confirmed on CT. The mean age of the patients was 13.9 years (9 to 21). They had a grade I or less spondylolisthesis and no evidence of intervertebral degeneration on MRI. The mean follow-up was four years (2.3 to 7.3). The patients were assessed by the Oswestry Disability Index (ODI) and a visual analogue scale (VAS). At the latest follow-up, 18 patients had an excellent clinical outcome, with a significant (p < 0.001) improvement in their ODI and VAS scores. The mean ODI score at final follow-up was 8%. Assessment of the defect by CT showed a rate of union of 80%. There were no complications involving the internal fixation. The strength of the construct removes the need for post-operative immobilisation

In our study, the aims were to describe the changes in the appearance of the lumbar spine on MRI in elite fast bowlers during a follow-up period of one year, and to determine whether these could be used to predict the presence of a stress fracture of the posterior elements. We recruited 28 elite fast bowlers with a mean age of 19 years (16 to 24) who were training and playing competitively at the start of the study. They underwent baseline MRI (season 1) and further scanning (season 2) after one year to assess the appearance of the lumbar intervertebral discs and posterior bony elements. The incidence of low back pain and the amount of playing and training time lost were also recorded.

In total, 15 of the 28 participants (53.6%) showed signs of acute bone stress on either the season 1 or season 2 MR scans and there was a strong correlation between these findings and the later development of a stress fracture (p < 0.001). The prevalence of intervertebral disc degeneration was relatively low. There was no relationship between disc degeneration on the season 1 MR scans and subsequent stress fracture. Regular lumbar MR scans of asymptomatic elite fast bowlers may be of value in detecting early changes of bone stress and may allow prompt intervention aimed at preventing a stress fracture and avoiding prolonged absence from cricket.

Lumbar spondylolysis is a stress fracture of the pars interarticularis. We have evaluated the site of origin of the fracture clinically and biomechanically. Ten adolescents with incomplete stress fractures of the pars (four bilateral) were included in our study. There were seven boys and three girls aged between 11 and 17 years. The site of the fracture was confirmed by axial and sagittal reconstructed CT. The maximum principal tensile stresses and their locations in the L5 pars during lumbar movement were calculated using a three-dimensional finite-element model of the L3-S1 segment. In all ten patients the fracture line was seen only at the caudal-ventral aspect of the pars and did not spread completely to the craniodorsal aspect. According to the finite-element analysis, the higher stresses were found at the caudal-ventral aspect in all loading modes. In extension, the stress was twofold higher in the ventral than in the dorsal aspect. Our radiological and biomechanical results were in agreement with our clinical observations

A review of the current literature shows that there is a lack of consensus regarding the treatment of spondylolysis and spondylolisthesis in children and adolescents. Most of the views and recommendations provided in various reports are weakly supported by evidence. There is a limited amount of information about the natural history of the condition, making it difficult to compare the effectiveness of various conservative and operative treatments. This systematic review summarises the current knowledge on spondylolysis and spondylolisthesis and attempts to present a rational approach to the evaluation and management of this condition in children and adolescents

It has been noted that bony union of a pars defect can be achieved in children if they wear a trunk brace. Our aim was to evaluate how the stage of the defect on CT and the presence or absence of high signal change in the adjacent pedicle on T2-weighted MRI were related to bony healing. We treated 23 children conservatively for at least three months. There were 19 boys and four girls with a mean age of 13.5 years (7 to 17). They were asked to refrain from sporting activity and to wear a Damen soft thoracolumbosacral type brace. There were 41 pars defects in 23 patients. These were classified as an early, progressive or terminal stage on CT. The early-stage lesions had a hairline crack in the pars interarticularis, which became a gap in the progressive stage. A terminal-stage defect was equivalent to a pseudarthrosis. On the T2-weighted MR scan the presence or absence of high signal change in the adjacent pedicle was assessed and on this basis the defects were divided into high signal change-positive or -negative. Healing of the defect was assessed by CT.

In all, 13 (87%) of the 15 early defects healed. Of 19 progressive defects, only six (32%) healed. None of the seven terminal defects healed. Of the 26 high signal change-positive defects 20 (77%) healed after conservative treatment whereas none of the high signal change-negative defects did so. We concluded that an early-stage defect on CT and high signal change in the adjacent pedicle on a T2-weighted MR scan are useful predictors of bony healing of a pars defect in children after conservative treatment.

We have analysed a number of radiological measurements in an attempt to clarify the predisposing factors for degenerative spondylolisthesis of the lumbosacral junction. We identified 57 patients with a slip and a control group of 293 patients without any radiological abnormality apart from age-related changes. The relative thickness of the L5 transverse process, the sacral table angle and the height of the iliac crest were measured and evaluated. The difference in these measurements between men and women was analysed in the control group.

We found that the transverse process of L5 was extremely slender, the sacral table more inclined, and the L5 vertebra was less deeply placed in the pelvis in patients with a slip compared with the control group. The differences in these three parameters were statistically significant.

We believe that the L5 vertebra is predisposed to slip when these factors act together on a rigidly-stabilised sacrum. This occurs more commonly in women, probably as a result of constitutional differences in the development of the male and female spine.

Low back injuries account for the greatest loss of playing time for professional fast bowlers in cricket. Previous radiological studies have shown a high prevalence of degeneration of the lumbar discs and stress injuries of the pars interarticularis in elite junior fast bowlers. We have examined MRI appearance of the lumbar spines of 36 asymptomatic professional fast bowlers and 17 active control subjects. The fast bowlers had a relatively high prevalence of multi-level degeneration of the lumbar discs and a unique pattern of stress lesions of the pars interarticularis on the non-dominant side. The systems which have been used to classify the MR appearance of the lumbar discs and pars were found to be reliable. However, the relationship between the radiological findings, pain and dysfunction remains unclear.

We present a case of L2/3 interspinous bursitis treated with extraspinal injections. No previous investigations have used fluoroscopically guided spinal injections to confirm the clinical relevance of the MRI features of this type of bursae. Autopsy studies have revealed an increased incidence of interspinous lumbar bursal cavities with advancing age. Afflicted patients present with localised, midline lower lumbar pain exacerbated by extension. In young athletes these symptoms can mimic spondylolysis. MRI is useful in detecting soft-tissue injury of the posterior elements. Fluoroscopically guided diagnostic and therapeutic extraspinal injections can be used for confirmation and treatment of pain from such bursae

Lumbar spondylolysis can heal with conservative treatment, but few attempts have been made to identify factors which may affect union of the defects in the pars. We have evaluated, retrospectively, the effects of prognostic variables on bony union of pars defects in 134 young patients less than 18 years of age with 239 defects of the pars who had been treated conservatively. All patients were evaluated by CT scans when first seen and more than six months later at follow-up. The results showed that the spinal level and the stage of the defects were the predominant factors. The site of the defects in the pars, the presence or development of spondylolisthesis, the condition of the contralateral pars, the degree of lumbar lordosis and the degree of lumbar inclination all significantly affected union

We studied prospectively 22 young athletes who had undergone surgical treatment for lumbar spondylolysis. There were 15 men and seven women with a mean age of 20.2 years (15 to 34). Of these, 13 were professional footballers, four professional cricketers, three hockey players, one a tennis player and one a golfer. Preoperative assessment included plain radiography, single positron-emission CT, planar bone scanning and reverse-gantry CT. In all patients the Oswestry disability index (ODI) and in 19 the Short-Form 36 (SF-36) scores were determined preoperatively, and both were measured again after two years in all patients. Three patients had a Scott’s fusion and 19 a Buck’s fusion. The mean duration of back pain before surgery was 9.4 months (6 to 36). The mean size of the defect as determined by CT was 3.5 mm (1 to 8) and the mean preoperative and postoperative ODIs were 39.5 (. sd. 8.7) and 10.7 (. sd. 12.9), respectively. The mean scores for the physical component of the SF-36 improved from 27.1 (. sd. 5.1) to 47.8 (. sd. 7.7). The mean scores for the mental health component of the SF-36 improved from 39.0 (. sd. 3.9) to 55.4 (. sd. 6.3) with p < 0.001. After rehabilitation for a mean of seven months (4 to 10) 18 patients (82%) returned to their previous sporting activity

We studied 23 patients with spondylolysis of the fifth lumbar vertebra (L5) and 20 with spondylolytic spondylolisthesis at this level. All were more than 40 years of age. The transverse processes at L5 were significantly wider in the former group than in the latter. We also dissected 56 cadavers to study the morphological relationship between the transverse process of L5 and the iliolumbar ligament, and found that the wider transverse process is associated with increased width of the posterior band of the iliolumbar ligament. If a patient with pars defects has wide transverse processes at L5, the lumbosacral junction may be stabilised by wide posterior bands of the iliolumbar ligament and the fifth lumbar vertebra by the ligament, preventing anterior displacement

We reviewed the radiographs of 325 unselected patients with defects in the pars interarticularis of L5 to study whether the incidence of vertebral slip in spondylolysis of L5 remained unchanged after the age of 20 years. MRI was also carried out on 111 of the patients to investigate the relationship between the shape of the transverse process of L5 and the degeneration of the discs adjacent to this level. The incidence of spondylolisthesis increased with age from 17% in the second decade to 51% in the sixth. The transverse process was significantly more slender in patients with less degeneration at L4/5 and advanced degeneration at L5/S1 than in patients with advanced degeneration at L4/5 and less degeneration at L5/S1. Vertebral slip secondary to an isthmic defect of L5 after the age of 20 years was confirmed and the adjacent disc degeneration was significantly related to the vertical thickness of the transverse process of L5

We injected methylene blue dye into 32 of the facet joints immediately above the defects in 17 consecutive patients with bilateral spondylolysis (34 defects). In 30 of these the dye flowed into a central cavity in the defect of the pars interarticularis and in 20 it passed into the facet joint below the defect. We found macroscopic cavities in 32 of the defects which communicated with the adjacent facet joints and had fibrous capsules. Histological examination showed focal areas of synovial lining consistent with a synovial pseudarthrosis. In most patients requiring surgery for spondylolysis, the defect is a synovial pseudarthrosis which communicates with the facet joint above it, and less often with the facet joint below it. We suggest that stress fractures of the pars may fail to heal because of the presence of synovial fluid from a nearby facet joint

Lateral oblique radiographs are considered important for the identification of spondylolytic lesions, but these projections will give a clear view only when the radiological beam is in the plane of the defect. We studied the variation in orientation of spondylolytic lesions on CT scans of 34 patients with 69 defects. There was a wide variation of angle: only 32% of defects were orientated within 15° of the 45° lateral oblique plane. Lateral oblique radiographs should not be considered as the definitive investigation for spondylolysis. We suggest that CT scans with reverse gantry angle are now more appropriate than oblique radiography for the assessment of spondylolysis. Variation in the angle of the defect may also need consideration when direct repair is being planned

We analysed the complications encountered in 102 consecutive patients who had posterolateral lumbosacral fusion performed with transpedicular screw and rod fixation for non-traumatic disorders after a minimum of two years. Of these, 40 had spondylolysis and spondylolisthesis, 42 a degenerative disorder, 14 instability after previous laminectomy and decompression, and six pain after nonunion of previous attempts at spinal fusion without internal fixation. There were 75 multilevel and 27 single-level fusions. There were 76 individual complications in 48 patients, and none in the other 54. The complications seen were screw misplacement, coupling failure of the device, wound infection, nonunion, permanent neural injury, and loosening, bending and breakage of screws. Screw breakage or loosening was more common in patients with multilevel fusions (p < 0.001). Screws of 5 mm diameter should not be used for sacral fixation. Forty-six patients had at least one further operation for one or several complications, including 20 fusion procedures for nonunion. The high incidence of complications is a disadvantage of this technically-demanding method

We studied the aetiology of vertebral slip in a long-term follow-up of 22 adult patients with isthmic spondylolysis or spondylolisthesis of L5. Of the 18 with spondylolysis without slip, 13 showed no slip after ten years, but five developed displacement of over 5%. All four patients with spondylolisthesis showed progression of the slip. We found that the vertical thickness of the transverse process of L5 was significantly greater (p < 0.01) in the 13 patients with no slip than in the other two groups. The relationship of vertebral slip to the shape of the transverse processes of L5 may be explained by differences in the bulk or physiological strength of the posterior bands of the iliolumbar ligament

We investigated 185 adolescents under the age of 19 years with spondylolysis. All but five were active in sport. The pars defect was classified into early, progressive and terminal stages. Of the 346 pars defects in 185 patients, 39.6% were early, 29.5% progressive and 30.9% in the terminal stages. Conservative management produced healing in 73.0% of the early, 38.5% of the progressive and none of the terminal defects. These results suggest that spondylolysis is caused by repetitive microtrauma during growth and can be successfully treated conservatively if treatment is started in the early stage. There was elongation of the pars interarticularis as the pars defect progressed, and this is likely to be a consequence of the defect rather than a contributing cause

Radiography and CT and MRI scans of the lumbar spine were performed in young patients complaining of pain during extension of the lumbar spine but without neurological signs in the lower limbs. T1-weighted MR images in the coronal plane showed a hypo-intense area in the pars interarticularis before the detection of spondylolysis at that site by plain radiography or CT. We suggest that this may be useful in the early diagnosis of spondylolysis

Some radiological features of the lumbar spine of 84 patients with spastic diplegia were compared with 50 control subjects. The average age of the patients was 20.1 years (3 to 39). Spondylolysis of the fifth lumbar vertebra was found in 21%, four times more frequently than in normal subjects. No patient under nine years of age had spondylolysis and the frequency increased with age. The average angle of lumbar lordosis in spastic patients in the standing position was greater than in normal subjects, and increased with age. The patients had a decreased sacrofemoral angle which caused an increase in Ferguson's angle and explained the increased angle of lumbar lordosis

Fast bowling in the game of cricket requires repetitive spinal extension, lateral deviation, lumbar flexion and thoracodorsal rotation. Back pain is common, and it has been shown that pars interarticularis defects had occurred in over 50% of a group of teenage fast bowlers. Many of these defects will heal, but some cause chronic pain which prevents bowling, although other activities may be painless. We report the successful results of local screw fusion of the pars interarticularis defects in ten bowlers, and recommend this method for this small group of sportsmen.

Between 1979 and 1989, we treated 22 patients with symptomatic lumbar spondylolysis which had not responded to conservative treatment by a modified Scott wiring technique to give direct repair of the lytic defects with stabilisation. The patients' mean age at the time of operation was 15 years; the mean follow-up period was four years. All 19 patients under 25 years old had satisfactory results. Two of the three patients over 25 years old had poor results. The age of the patient at surgery seems to be an important determinant of outcome. Radiologically confirmed fusion is of secondary importance. The presence of a grade I spondylolisthesis did not prejudice the result. We recommend the Scott wiring technique to stabilise the direct repair of a lumbar spondylolysis

We present a 26-year-old athlete with severe low back pain associated with a fracture of a lumbar pedicle and contralateral spondylolysis. The difficulties of diagnosis are discussed together with the subject of segmental pain referral. A technique of operative management is described involving instrumentation of the symptomatic level alone

Two different classifications of discograms have been used in a prospective study of 279 injected discs in 100 patients. The five-stage classification of Adams, Dolan and Hutton (1986) showed increased degeneration in the lower lumbar discs and more degenerative changes in men than in women. Exact reproduction of the patient's pain on injection was more common in fissured or ruptured discs than in less degenerate discs, with 81% sensitivity and 64% specificity of the discogram for pain. The additional information obtained by comparing computerised tomography (CT) with discograms was minimal. Discography was found to be useful in the evaluation of chronic low back pain in patients whose ordinary CT scans, myelograms and flexion-extension radiographs were normal. In spondylolysis and spondylolisthesis, discography can disclose whether fusion needs to be extended above the lytic level, and it may show if the pain in patients who have had posterolateral fusion is discogenic. Thus, discography gives information which is useful in deciding whether to operate on patients with chronic low back pain

We reviewed 20 adult patients with spondylolysis and isthmic spondylolisthesis an average of 10.5 years after treatment by anterior spinal fusion. Nineteen patients had excellent or satisfactory results. Ten of the patients were symptom-free at one year, and 15 were asymptomatic at final follow-up. Anterior spinal fusion can produce results comparable to those of posterior fusion with or without decompression. The results tend to improve with time in contrast to the known worsening of late results after posterior decompression without fusion

We report the occurrence of spondylolysis and/or spondylolisthesis of the lumbar vertebrae in five patients with osteopetrosis, four of them having multiple lesions. The case histories indicate that spondylolysis had developed in the pathological bone as a result of increased stress and that it is an acquired lesion

Reports of spondylolysis in vertebrae other than those of the lower lumbar spine are rare. We report 32 patients with upper lumbar spondylolysis who have been studied clinically, radiologically and scintigraphically. Twenty patients had bilateral lesions, and seven of those with unilateral lesions had structural changes or anomalies in the opposite posterior arch. Positive scans were found to be associated with a short clinical history, and indicated stress-related lesions. Our findings suggest that mechanical factors may play a role in the aetiology of spondylolysis in the upper lumbar spine similar to that which they play in the lower lumbar spine, and that local structural anomalies may contribute to abnormal loading of these vertebrae

In 66 patients with back pain and suspected spondylolysis, the results of bone scintigraphy have been correlated with operative findings and clinical follow-up. Although bone scintigraphy is of little value for primary diagnosis, it helps to distinguish between those patients with established non-union of the defect, and those in whom healing is still progressing and who may benefit from immobilisation. We also found that increased uptake on the contralateral side to a unilateral spondylolysis is suggestive of impending fracture

Thirty-four bony specimens of isthmic spondylolysis were examined and, in a significant number (32%), stenosis of the intervertebral foramen was noted. Although not emphasised in previous reports, this finding may be an important factor in the aetiology of nerve root compression when this is associated with spondylolysis and spondylolisthesis. Anatomical guidelines for adequate surgical decompression are suggested

Spondylolysis occurring after a spinal fusion is considered to result from operative damage to the pars interarticularis on both sides. Fourteen cases are reported, and compared with the 23 cases which have previously been published. The defects are usually recognised within five years of fusion, and usually occur immediately above the fusion mass. Other contributory causes may be: fatigue fracture from concentration of stress; damage and altered function of the posterior ligament complex; and degenerative disc disease immediately above or below the fusion. Fusion technique is critical, since virtually all cases occurred after posterior interlaminar fusions. This complication is easily overlooked in patients with recurrent back pain after an originally successful posterior spinal fusion.

Five vertebrae with unilateral spondylolysis are presented. The associated asymmetry of the posterior elements supports the concept of a localised form of growth deficiency. The defect is difficult to demonstrate radiologically, and is perhaps present more frequently than is recognised. It should be suspected clinically from asymmetry of the neural arch and from unilateral wedging of the vertebral body, and may be demonstrated by further radiographic examination. The clinical significance is uncertain, but one patient is presented in whom unilateral spondylolysis was associated with intermittent sciatic pain