TY - GEN
T1 - Segmental Instability in the Degenerative Lumbar Spine
AU - Forbech Elmose, Signe
PY - 2023/6/7
Y1 - 2023/6/7
N2 - Degenerative lumbar spinal stenosis (LSS) and spondylolisthesis (LDS) are commonconditions and the most frequent cause for spinal surgery in patients older than 65years. Spondylolisthesis means a vertebra has translated/slipped forward. This occursin approximately 10% of patients with LSS. The conditions are caused bydegenerative changes narrowing the spinal canal. The cardinal symptoms are reducedwalking distance and varying degrees of leg and back pain. Additionally, somepatients have excessive movement between vertebrae. This is termed segmentalinstability and is believed to aggravate symptoms and complicate the condition.Dynamic instability has previously been defined and diagnosed radiologically byflexion and extension radiographs showing excessive movement. During the lastdecades Magnetic Resonance Imagining (MRI) have become the preferred diagnosticmodality to confirm the diagnosis of LSS. While conducting an MRI the patient is in asupine non weight-baring position. This can cause reposition of the translatedvertebrae, hereby inducing a risk of overlooking instability. Studies have found MRIsigns that may be associated with instability. Consensus on how to define anddiagnose instability is lacking and its influence on symptoms and outcomes aftersurgical treatment has been debated for almost a century.The purpose of this thesis was to define segmental instability in the degenerativelumbar spine, and to investigate if MRI findings could be proxies for instability.Moreover, to investigate if patient reported outcomes (PRO) at long-term follow-upafter decompression surgery were associated with preoperative presence of MRIproxies for instability in LSS patients. The thesis is based on three sub-studies,described in the following. dynamic angulation. The most frequently reported cut-off for abnormal dynamictranslation was > 3 mm and for dynamic angulation 10.Study IIA retrospective cohort study on patients with LSS and LDS how underwentdecompression or fusion surgery on level L4-L5 investigating if facet angle, faceteffusion, preserved disc height and translation on MRI (MRIPs) were associated withinstability. Patients were divided in two groups based on radiographic instability onstanding radiograph defined as > 3 mm translation. There were 47 patients in thestable group and 185 in the instability group. There were statistically significantassociation between MRIPs (> 3 mm translation on MRI, facet angle ≥ 46, faceteffusion ≥ 1.5 mm, disc height index ≥ 13%) and instability on standing radiograph.There were significant association between MRIPs and instability even without MRItranslation.Study IIIA retrospective cohort study of Danish and Swedish patients with symptomatic LSSwithout translation on MRI who had undergone decompression surgery, with the aimto investigate the long-term patient reported results. The patients were divided intotwo groups based upon presence of MRIPs for instability. One-hundred three patientsincluded, 83 MRIP(-) and 21 MRIP(+). Propensity matching resulted in 21 in eachgroup with comparable baseline demographics and PROs reflecting of disability,health related quality of life and pain. At five-year follow-up both groups hadstatistically significant improvement in PROs compared to baseline. No difference inPROs between the groups, except MRIP(+) showed statistically significant worse legpain.ConclusionDespite various definitions the most frequent definition for segmental instability was >3 mm dynamic translation. Presence of MRIPs for instability showed statisticallysignificant association with instability on standing radiograph, even without MRItranslation. In patients with LSS and MRI translation < 3 mm, presence of MRIPs forinstability preoperatively may be associated with less improvement in leg pain five-years after decompression only surgery. However, presence of instability did notinfluence negatively on other PROs.Study IA systematic review conducted according to the Preferred Reporting Items forSystematic Reviews and Meta-analysis (PRIMSA) guidelines. Literature searchundertaken in relevant databases. One-hundred eighteen papers with a definition ofsegmental instability was included. The definitions were grouped, which showed that24% defined instability by dynamic translation and 26% by dynamic translation and
AB - Degenerative lumbar spinal stenosis (LSS) and spondylolisthesis (LDS) are commonconditions and the most frequent cause for spinal surgery in patients older than 65years. Spondylolisthesis means a vertebra has translated/slipped forward. This occursin approximately 10% of patients with LSS. The conditions are caused bydegenerative changes narrowing the spinal canal. The cardinal symptoms are reducedwalking distance and varying degrees of leg and back pain. Additionally, somepatients have excessive movement between vertebrae. This is termed segmentalinstability and is believed to aggravate symptoms and complicate the condition.Dynamic instability has previously been defined and diagnosed radiologically byflexion and extension radiographs showing excessive movement. During the lastdecades Magnetic Resonance Imagining (MRI) have become the preferred diagnosticmodality to confirm the diagnosis of LSS. While conducting an MRI the patient is in asupine non weight-baring position. This can cause reposition of the translatedvertebrae, hereby inducing a risk of overlooking instability. Studies have found MRIsigns that may be associated with instability. Consensus on how to define anddiagnose instability is lacking and its influence on symptoms and outcomes aftersurgical treatment has been debated for almost a century.The purpose of this thesis was to define segmental instability in the degenerativelumbar spine, and to investigate if MRI findings could be proxies for instability.Moreover, to investigate if patient reported outcomes (PRO) at long-term follow-upafter decompression surgery were associated with preoperative presence of MRIproxies for instability in LSS patients. The thesis is based on three sub-studies,described in the following. dynamic angulation. The most frequently reported cut-off for abnormal dynamictranslation was > 3 mm and for dynamic angulation 10.Study IIA retrospective cohort study on patients with LSS and LDS how underwentdecompression or fusion surgery on level L4-L5 investigating if facet angle, faceteffusion, preserved disc height and translation on MRI (MRIPs) were associated withinstability. Patients were divided in two groups based on radiographic instability onstanding radiograph defined as > 3 mm translation. There were 47 patients in thestable group and 185 in the instability group. There were statistically significantassociation between MRIPs (> 3 mm translation on MRI, facet angle ≥ 46, faceteffusion ≥ 1.5 mm, disc height index ≥ 13%) and instability on standing radiograph.There were significant association between MRIPs and instability even without MRItranslation.Study IIIA retrospective cohort study of Danish and Swedish patients with symptomatic LSSwithout translation on MRI who had undergone decompression surgery, with the aimto investigate the long-term patient reported results. The patients were divided intotwo groups based upon presence of MRIPs for instability. One-hundred three patientsincluded, 83 MRIP(-) and 21 MRIP(+). Propensity matching resulted in 21 in eachgroup with comparable baseline demographics and PROs reflecting of disability,health related quality of life and pain. At five-year follow-up both groups hadstatistically significant improvement in PROs compared to baseline. No difference inPROs between the groups, except MRIP(+) showed statistically significant worse legpain.ConclusionDespite various definitions the most frequent definition for segmental instability was >3 mm dynamic translation. Presence of MRIPs for instability showed statisticallysignificant association with instability on standing radiograph, even without MRItranslation. In patients with LSS and MRI translation < 3 mm, presence of MRIPs forinstability preoperatively may be associated with less improvement in leg pain five-years after decompression only surgery. However, presence of instability did notinfluence negatively on other PROs.Study IA systematic review conducted according to the Preferred Reporting Items forSystematic Reviews and Meta-analysis (PRIMSA) guidelines. Literature searchundertaken in relevant databases. One-hundred eighteen papers with a definition ofsegmental instability was included. The definitions were grouped, which showed that24% defined instability by dynamic translation and 26% by dynamic translation and
U2 - 10.21996/qf1j-t234
DO - 10.21996/qf1j-t234
M3 - Ph.D. thesis
PB - Syddansk Universitet. Det Sundhedsvidenskabelige Fakultet
ER -