Primary stability of the Activ L® intervertebral disc prosthesis in cadaver bone and comparison of the keel and spike anchoring concept.

BACKGROUND: High primary stability is the key prerequisite for safe osseointegration of cementless intervertebral disc prostheses. The aim of our study was to determine the primary stability of intervertebral disc prostheses with two different anchoring concepts - keel and spike anchoring. METHODS: Ten ActivL intervertebral disc prostheses (5 x keel anchoring, 5 x spike anchoring) implanted in human cadaver lumbar spine specimens were tested in a spine movement simulator. Axial load flexion, extension, left and right bending and axial rotation motions were applied on the lumbar spine specimens through a defined three-dimensional movement program following ISO 2631 and ISO/CD 18192-1.3 standards. Tri-dimensional micromotions of the implants were measured for both anchor types and compared using Student's T-test for significance after calculating 95 % confidence intervals. RESULTS: In the transverse axis, the keel anchoring concept showed statistically significant (p < 0.05) lower mean values of micromotions compared to the spike anchoring concept. The highest micromotion values for both types were observed in the longitudinal axis. In no case the threshold of 200 micrometers was exceeded. CONCLUSIONS: Both fixation systems fulfill the required criteria of primary stability. Independent of the selected anchorage type an immediate postoperative active mobilization doesn't compromise the stability of the prostheses.

Does osteoporosis reduce the primary tilting stability of cementless acetabular cups?

BACKGROUND: Cementless hip cups need sufficient primary tilting stability to achieve osseointegration. The aim of the study was to assess differences of the primary implant stability in osteoporotic bone and in bone with normal bone density. To assess the influence of different cup designs, two types of threaded and two types of press-fit cups were tested. METHODS: The maximum tilting moment for two different cementless threaded cups and two different cementless press-fit cups was determined in macerated human hip acetabuli with reduced (n=20) and normal bone density (n=20), determined using Q-CT. The tilting moments for each cup were determined five times in the group with reduced bone density and five times in the group with normal bone density, and the respective average values were calculated. RESULTS: The mean maximum extrusion force of the threaded cup Zintra was 5670.5 N (max. tilting moment 141.8 Nm) in bone with normal density and.5748.3 N (max. tilting moment 143.7 Nm) in osteoporotic bone. For the Hofer Imhof (HI) threaded cup it was 7681.5 N (192.0 Nm) in bone with normal density and 6828.9 N (max. tilting moment 170.7 Nm) in the group with osteoporotic bone. The mean maximum extrusion force of the macro-textured press-fit cup Metallsockel CL was 3824.6 N (max. tilting moment 95.6 Nm) in bone with normal and 2246.2 N (max. tilting moment 56.2 Nm) in osteoporotic bone. For the Monoblock it was 1303.8 N (max. tilting moment 32.6 Nm) in normal and 1317 N (max. tilting moment 32.9 Nm) in osteoporotic bone. There was no significance. A reduction of the maximum tilting moment in osteoporotic bone of the ESKA press-fit cup Metallsockel CL was noticed. CONCLUSION: Results on macerated bone specimens showed no statistically significant reduction of the maximum tilting moment in specimens with osteoporotic bone density compared to normal bone, neither for threaded nor for the press-fit cups. With the limitation that the results were obtained using macerated bone, we could not detect any restrictions for the clinical indication of the examined cementless cups in osteoporotic bone.

Does intraoperative application of leukocyte-poor platelet-rich plasma during arthroscopy for knee degeneration affect postoperative pain, function and quality of life? A 12-month randomized controlled double-blind trial.

INTRODUCTION: We aimed to identify the effects of intraoperative applied leukocyte-poor platelet-rich plasma (LP-PRP) during knee arthroscopy for degenerative lesions involving pain, function and quality of life. METHODS: We performed a randomized controlled, double-blind trial (RCT) including 58 patients for arthroscopic knee surgery for cartilage or meniscal degeneration with allocation into the LP-PRP (n = 24) or control group (n = 34). During arthroscopy, LP-PRP was injected intra-articular in the intervention group. At baseline, 6 weeks, 6 months and 12 months pain, function, and life quality were assessed. RESULTS: 91 % of enrolled patients were available for 12 months follow-up. Pain was significantly lower in the LP-PRP group (VAS 0.9. vs. 2.3) at 6 (p = 0.008) but not at 12 months (VAS 1.0 vs. 1.6, p = 0.063). LP-PRP application improved the Lysholm Score at 6 (77.5 vs. 65.6, p = 0.033) and 12 months (83.2 vs.70.0, p = 0.007). Assessment of life quality (SF-36) concerning the physical component summary was significantly higher at 6 weeks (33.9 vs. 25.6, p = 0.001) and 6 months (29.9 vs. 27.1, p = 0.027) in the LP-PRP group but equal at 1 year (31.4 vs. 30.1, p = 0.438). CONCLUSIONS: Intraoperative application of LP-PRP may enhance pain reduction and gain of knee function within 6-12 months compared to arthroscopy alone. LEVEL OF EVIDENCE: II, randomized controlled clinical trial with reduced power. CLINICALTRIALS. GOV IDENTIFIER: NCT02189408.

Biomechanical and functional indicators in male semiprofessional soccer players with increased hip alpha angles vs. amateur soccer players.

BACKGROUND: Femoroacetabular impingement (FAI) is predominant in young male athletes, but not much is known about gait differences in cases of increased hip alpha angles. In our study, the hip alpha angle of Nötzli of soccer players was quantified on the basis of magnetic resonance imaging (MRI) with axial oblique sequences. The aim of the current study was to compare the rearfoot motion and plantar pressure in male semiprofessional soccer players with increased alpha angles to age-matched amateur soccer players. METHODS: In a prospective analysis, male semiprofessional and amateur soccer players had an MRI of the right hip to measure the alpha angle of Nötzli. In a biomechanical laboratory setting, 14 of these participants in each group ran in two shoe conditions. Simultaneously in-shoe pressure distribution, tibial acceleration, and rearfoot motion measurements of the right foot were performed. RESULTS: In the semiprofessional soccer group, the mean value of the alpha angle of group was 55.1 ± 6.58° (range 43.2-76.6°) and 51.6 ± 4.43° (range 41.9-58.8°) in the amateur group. In both shoe conditions, we found a significant difference between the two groups concerning the ground reaction forces, tibial acceleration, rearfoot motion and plantar pressure parameters (P < 0.01, P < 0.05, P = 0.04). Maximum rearfoot motion is about 22% lower in the semiprofessional group compared to the amateur group in both shoe conditions. CONCLUSIONS: This study confirmed that semiprofessional soccer players with increased alpha angles showed differences in gait kinematics compared to the amateur group. These findings support the need for a screening program for competitive soccer players. In cases of a conspicuous gait analysis and symptomatic hip pain, FAI must be ruled out by further diagnostic tests.

The deviation of the mechanical leg axis correlates with an increased hip alpha angle and could be a predictor of femoroacetabular impingement.

PURPOSE: This study was designed to evaluate whether the mechanical axis deviation (MAD) of the leg correlates with an increased hip alpha angle as described by Nötzli, which is associated with femoroacetabular impingement (FAI). METHODS: In a retrospective analysis, standing full-length anteroposterior radiographs were analysed in patients who suffered from symptomatic leg alignment. The study included 85 radiographs of 80 patients with an average age of 43.11 years (range 18-60 years). Five patients underwent a bilateral long-leg X-ray examination. All radiographs were transferred as Digital Imaging and Communications in Medicine data files from the Picture Archiving and Communications System into the OrthoPlanner software version 2.3.2. The radiographs were measured by one orthopaedic surgeon and one independent radiologist. RESULTS: The mean value of the alpha angle of Nötzli was 61.43° (49.07-74.04°). A total of 57 (67%) radiographs showed a varus deviation, 25 (29.5%) had a valgus malalignment and three (3.5%) a straight leg axis. Of 82 radiographs, 40 (48.8%) had a moderate axis deviation with a MAD <15 or > - 15 mm and a mean alpha angle of 57.81°, and 42 (51.2%) with extended axis deviation of a MAD > 15 or < - 15 mm had a mean alpha angle of 62.93°; 40 (95.2%) of these 42 showed an alpha angle > 55°. The alpha angle was significantly increased in extended axis deviation compared to moderate axis deviation (P = 0.001). CONCLUSIONS: This study confirmed that increased alpha angles were found significantly at higher degrees of axis deviation on the full-length radiograph. In cases of a MAD >15 or < - 15 mm and symptomatic coxalgia, diagnostic tests must be pursued for FAI.

Prevalence of femoro-acetabular impingement in international competitive track and field athletes.

PURPOSE: The aim of our study was to analyse the prevalence of femoro-acetabular impingement (FAI) in national elite track and field athletes compared to peers using magnetic resonance imaging (MRI) and clinical examination including impingement tests. METHODS: A total of 44 participants (22 national elite track and field athletes and 22 non-athletes) underwent an MRI for radiological findings associated with FAI, including alpha angle, lateral centre edge angle (CEA), findings of labral and cartilage lesions. The study group was furthermore investigated by the hip outcome score (HOS) and a clinical hip examination including range of motion (ROM) and impingement tests. RESULTS: Concerning the cam impingement, there was a significant difference measured by mean alpha angle between the athlete group (52.2 ± 7.29°) and the control group (48.1 ± 5.45°, P = 0.004). Eleven athletes showed a cam impingement, while two probands of the control group had a pincer impingement and one a mixed form (P = 0.0217). There was no statistically significant difference concerning the CEA upon evaluating pincer impingement. Seven track and field athletes had a positive impingement test, whereof three had an increased alpha angle >55°. No participant of the control group showed pathological results in the impingement test (P = 0.0121). CONCLUSIONS: MRI evidence and clinical examination suggest that cam impingement is more common in elite athletes in comparison to non-athletes. At a professional level, the intense practice of track and field athletics is susceptible for FAI.

Comparative study of the femoroacetabular impingement (FAI) prevalence in male semiprofessional and amateur soccer players.

INTRODUCTION: Femoroacetabular impingement (FAI) represents a novel approach to the mechanical etiology of hip osteoarthritis. The cam-type femoroacetabular impingement deformity occurs frequently in young male athletes. The aim of our study was to evaluate the prevalence of FAI in male semiprofessional soccer players using clinical examination and magnetic resonance imaging (MRI), compared to amateur soccer players. In MRI, the α angle of Nötzli is determined for quantifying FAI. MATERIALS AND METHODS: According to power analysis, a total of 22 asymptomatic semiprofessional soccer players with a median of 23.3 years of age (range 18-30 years) and 22 male amateur soccer players with a median of 22.5 years of age (control group, range 18-29 years) underwent an MRI to measure the hip α angle of Nötzli. The α angle of the kicking legs of the semiprofessional group and the amateur group were analyzed. The study group was moreover evaluated by the Hip Outcome Score (HOS) and a clinical hip examination including range of motion (ROM) and impingement tests. RESULTS: In the semiprofessional group, 19 soccer players had a right kicking leg and 1 soccer player had a left kicking leg. 2 soccer players kicked with two feet. In the semi-professional group, the mean value of the α angle of the kicking leg (57.3 ± 8.2°) was significantly higher than in the amateur group (51.7 ± 4.8°, P = 0.008). In the semi-professional group, 15 (62.5 %) of 24 kicking legs had an increased α angle >55°, while 5 (27.3 %) kicking legs of the amateur group had an α angle >55°. Five semi professional soccer players had findings in clinical examination, whereof 4 had an increased α angle >55°. No participant of the amateur group showed pathological results in the clinical examination (P = 0.0484). Overall, semiprofessional soccer players had a higher proportion of an increased α angle than the amateur group. CONCLUSIONS: Semiprofessional players have a higher prevalence of an increased α angle in the kicking leg than the amateur group at the same age. The kicking leg is predisposed for FAI.

Joint line reconstruction in medial unicompartmental knee arthroplasty: development and validation of a measurement method.

PURPOSE: Preservation of the joint line in total knee arthroplasty (TKA) has shown to be an important factor for the long-term outcome, especially in revision TKA. For unicompartmental knee arthroplasty (UKA), the role of the joint line has neither been investigated nor is it consciously respected during implantation. Thus, the aim was to establish and validate a standardised measurement method to determine the joint line in UKA. METHODS: As there is no established method to evaluate changes in the joint line radiologically, we introduced two methods and correlated them. The methods were first validated in a cadaver model by a controlled rotational study. Then, the joint line of 29 patients with an UKA (Oxford, Biomet, Bridgend, UK) was determined on pre- and post-operative radiographs. Both methods were tested by intra- and inter-rater reliability. RESULTS: Both methods showed a good intra- and inter-rater reliability. Furthermore, there was only little bias in agreement between both methods and raters. Measurements of the 29 UKA patients revealed that the joint line was more distally by a mean of 4.4 ± 1.2 mm after surgery. CONCLUSIONS: The study provides for the first time a reliable and standardised measurement tool to determine the changes in the joint line after implantation of an UKA. The instrument should be used in further studies to evaluate the impact of the joint line on the long-term outcome, the load in the two non-replaced knee compartments and on the ligaments.

Analysis of the sensory innervations of the greater trochanter for improving the treatment of greater trochanteric pain syndrome.

In medical practice, greater trochanteric pain syndrome has an incidence of 5.6 per 1,000 adults per year, and affects up to 25% of patients with knee osteoarthritis and low back pain in industrialized nations. It also occurs as a complication after total hip arthroplasty. Different etiologies of the pain syndrome have been discussed, but an exact cause remains unknown. The purpose of this study was to obtain a better understanding of the sensory innervations of the greater trochanter in attempt to improve the treatment of this syndrome. Therefore, we dissected the gluteal region of seven adult and one fetal formalin fixed cadavers, and both macroscopic and microscopic examination was performed. We found a small sensory nerve supply to the periosteum and bursae of the greater trochanter. This nerve is a branch of the n. femoralis and accompanies the arteria and vena circumflexa femoris medialis and their trochanteric branches to the greater trochanter. This nerve enters the periosteum of the greater trochanter directly caudal to the tendon of the inferior gemellus muscle. This new anatomical information may be helpful in improving therapy, such as interventional denervation of the greater trochanter or anatomically guided injections with corticosteroids and local anesthetics.

Heat distribution of polymerisation temperature of bone cement on the spinal canal during vertebroplasty.

PURPOSE: In the last 15 years, vertebroplasty and kyphoplasty have become established operative procedures for treating osteoporotic vertebral-body fractures and vertebral bodies afflicted with metastases. These procedures are quickly performed with few personnel and material resources and have a low rate of complications. However, cases of neurological impairment are reported in the scientific literature. We analysed whether potentially harmful heat is radiated/conducted by the polymerisation temperature of polymethylmethacrylate (PMMA) bone cement in the spinal canal. METHODS: We performed vertebroplasty on 25 vertebral bodies and measured the temperature distribution during polymerisation of bone cement within the spinal canal using heat probes placed in the respective areas. The vertebral bodies were located in a circulating water bath at 37°C. RESULTS: During polymerisation of the bone cement, a temperature rise was measured. The peak temperature was reached after few minutes. Temperature curves differed; a maximum temperature of up to 43.16°C was detected for a few seconds only. CONCLUSION: When vertebroplasty is performed correctly, there is no temperature development that could eventually damage the spinal cord or spinal nerves.

Experimental measurements of micromotions of the cementless intervertebral disc prostheses in the cadaver bone.

BACKGROUND: Sufficient primary stability is mandatory for successful bony prosthetic incorporation. Therefore, defined micromotion values of 150 µm should not be exceeded as higher values might compromise the ingrowth of bone trabeculae to the implant surface. The aim of this study was to evaluate the primary stability of different cementless disc prosthesis in a cadaver model. METHODS: Four different implants with different anchoring and bearing concept were tested with a target level of L4/5. 26 specimens were randomly allocated to 1 of the 4 different implants with 6 speciments in each group. Two groups were formed depending on the anchoring (spikes vs. fin) and bearing concept (non-/semi- vs. constrained). Each implant was tested regarding primary stability in a hydraulic simulator allowing simultaneous polyaxial segment movements and axial loading. The measurements were recorded on the lower plate of the prosthesis. FINDINGS: The majority of the implants showed micromotion values below 200 µm in all planes. Only one prosthesis presented borderline longitudinal amplitudes that were significant higher than the other planes. Furthermore, significant differences were observed in the sagittal plane when comparing spike and keel anchoring. Spike anchoring implants showed superior tresults to keel anchoring implants (40 µm vs. 55 µm; p = .039), while the non-/semi-constrained bearing concept was more advantageous compared to constrained group (40 µm vs. 63 µm; p = .001). INTERPRETATION: Spike anchoring and non-constrained implants might provide better primary stability.

Influence of different fixation methods on the fracture force of osteoporotic human lumbar vertebral bodies in the generation of vertebral compression fractures.

BACKGROUND: The use of fresh-frozen (FF) specimens represents the gold standard for biomechanical investigations. Since FF specimens are often difficult to obtain, chemical-fixed specimens (formalin (FA), Thiel (TH)) are also used. OBJECTIVE: Since fixation methods can alter the mechanical properties of bone tissue, the purpose of this study was to examine their influence on the fracture force of lumbar vertebral bodies (VB). METHODS: First the VB were subdivided into three focus groups: FF, TH, and FA. After removing the soft tissue and the processus transverses of all VB, the endplates were planned with a thin layer of epoxy resin, in order to apply a constant strain to the surface and sub-surface. The VB were subjected to axial compression tests in order to determine fracture force. Lastly a standardized compression fracture was generated. RESULTS: The mean values of the fracture force of the focus groups were 4529.5 N (FF), 3211.3N (TH) and 2947.9N (FA). Consequently a significant difference between the FF and the other two groups could be demonstrated (p< 0.05). CONCLUSION: The preliminary tests showed that the fraction force of fresh-frozen VB were significantly higher than TH/FA-fixed VB. Therefore, these fixation methods could potentially have an influence on the biomechanical properties of VB. This leads to the assumption that if load-to-failure tests are performed, it is probably recommended to use fresh-frozen specimens.

Can serum procalcitonin help to differentiate between septic and nonseptic arthritis?

PURPOSE: The aim of this study was to evaluate the usefulness of serum procalcitonin (PCT) to differentiate between septic and nonseptic acute arthritis. METHODS: Thirty-three patients who presented to our outpatient clinics with the symptoms of acute arthritis of unknown origin were enrolled in this study. We determined the serum concentrations of PCT and C-reactive protein and performed a white blood cell count. The definitive diagnosis was determined by microbiologic examination of a joint aspirate. RESULTS: Microbiologic cultures showed that 15 patients had septic arthritis. In these patients the PCT levels were significantly increased compared with those in the 18 patients with nonseptic arthritis (mean +/- SD, 1.18 +/- 1.66 ng/mL v 0.078 +/- 0.073 ng/mL; P = .001). On the basis of the normal range (<0.5 ng/mL), the test sensitivity in our series was 53.3% with a specificity of 100%. C-reactive protein levels in patients with septic arthritis were also significantly elevated compared with the nonseptic group. Because in either group no value was within the normal range (<0.5 mg/dL), the specificity was 0%. CONCLUSIONS: In this study serum PCT levels of patients with septic arthritis were significantly higher than those of patients with nonseptic arthritis (P = .001). However, the sensitivity when referencing the normal upper limit of PCT (0.5 ng/mL) is not high enough to establish a diagnosis based exclusively on serum parameters. This reflects the results of other studies examining localized infections without generalized bacteremia. The data suggest that a specific PCT cutoff level for localized infections could be helpful in the future. LEVEL OF EVIDENCE: Level III, diagnostic study of nonconsecutive patients without consistently applied reference gold standard.

Fracture generation in human vertebrae under compression loading: The influence of pedicle preservation and bone mineral density on in vitro fracture behavior.

BACKGROUND: Fractured vertebral bodies are a common and wide spread health issue. OBJECTIVE: The purpose of this study was to develop a standardized method to experimentally generate compression fractures in vertebral bodies. The influence of the pedicles has been investigated with regards to the fracture behavior. The correlation between bone mineral density (BMD), the cause of fractures and the fracture behavior was investigated. METHODS: Twenty-one fresh frozen human lumbar spines were examined for bone mineral density (BMD) by means of quantitative computed tomography (qCT). All soft tissue was removed, vertebrae were carefully separated from each other and the exposed cranial and caudal endplates were covered with a thin layer of resin to generate a plane and homogeneous surface. A total of 80 vertebral bodies were tested until fracture. RESULTS: A good positive correlation was found between BMD, fracture compression force and stiffness of the vertebral body. No significant differences were found between the fractures generated in vertebral bodies with and without pedicles, respectively. CONCLUSIONS: Our model represents a consolidation of already existing testing devices. The comparative measurement of the BMD and the fracture behavior shows validity. In contrast to other authors, the force was applied to the whole vertebral body. Furthermore the upper and lower plates were not parallelized and therefore the natural anatomic shape was imitated. Fracture behavior was not altered by removing the pedicles.

Cartilage Surgery in Overweight Patients: Clinical and MRI Results after the Autologous Matrix-Induced Chondrogenesis Procedure.

Modern orthopaedic surgery provides a variety of techniques for cartilage repair. The Autologous Matrix-Induced Chondrogenesis (AMIC) procedure is a single-step technique with a collagen I/III scaffold for the treatment of full-thickness cartilage lesions. The aim of the study was to analyze the outcome of the AMIC procedure in overweight patients with knee cartilage defects. Overweight patients treated with AMIC surgery were followed up by clinical and MRI examination. 9 patients with a cartilage defect of the knee with a mean lesion size of 2.1 ± 1.2 cm2 and an average body mass index (BMI) of 29.3 were available for the follow-up. The Lysholm Score was significantly improved by the AMIC procedure (38 to 67, p ≤ 0.008). The VAS Score was significantly lower after the procedure (9 to 3, p ≤ 0.018). In the postoperative MOCART Scale, the scaffold reached defect covering of 80%. However, 2 patients had to be revised due to persisting knee pain. The AMIC procedure enhances pain reduction and gain of knee function for cartilage defects of overweight patients. However, in cases of an increased BMI, the patient had to be informed that success rate is reduced despite good defect covering.

Medial branch blocks versus pericapsular blocks in selecting patients for percutaneous cryodenervation of lumbar facet joints.

BACKGROUND AND OBJECTIVES: At many institutions, it is not practically feasible to perform a series of controlled or placebo-controlled medial branch blocks on several facet joints in order to select patients for facet joint rhizotomy. As for uncontrolled blocks, there is no proof that medial branch blocks are superior to other types of blocks. This study was performed to compare medial branch blocks to simple pericapsular blocks for the selection of patients for lumbar facet joint cryodenervation. METHODS: Patient selection was based on history, imaging, and physical examination. Diagnostic blocks were either medial branch blocks or pericapsular blocks. Percutaneous medial branch cryodenervation was performed by use of a Lloyd Neurostat 2000. Outcome parameters were low back pain (visual analog scale [VAS]), limitation of activity (Macnab), and overall satisfaction. A total of 26 patients were recruited, 13 for each group. Follow-up was 6 months. RESULTS: Patients who had been selected by medial branch blocks had better pain relief than did patients who had been diagnosed by use of pericapsular blocks. At 6 weeks and at 3 months after treatment, these results reached statistical significance (VAS 2.2 v 4.2, P < .05). CONCLUSIONS: Our results suggest that uncontrolled medial branch blocks are superior to pericapsular blocks in selecting patients for facet joint cryodenervation, but both blocks work. If serial controlled blocks cannot be used, lumbar facet joint pain remains a diagnostic dilemma.

Age dependent changes of the facet joint alignment for cervical disc replacement: A radiographic evaluation.

BACKGROUND: Artificial cervical disc implants are meant to last for several decades and therefore it is of interest, how the cervical facet joints undergo physiological changes over the course of years. OBJECTIVE: The primary purpose of this study is to investigate an age dependent deformation in human cervical facet joints. MATERIAL AND METHODS: The motion segments C2 to Th1 were measured in the cervical X-rays of 131 patients, aged between 14 and 88 years. The cranial and caudal facet joint angles were determined for each segment. The linear regression between the facet joint angle and age was determined. Furthermore the average as well as the standard deviation of the facet joint angle was determined for two groups, one group aged up to 57 years and the other group from 58 years upwards. The results were compared by means of the t-test. RESULTS: The angles of the cranial facet joint surfaces C3-C7 ranged from 54° to 64°, those of the caudal facet joint surfaces C3-C7 from 52° to 58°. The alignment of both, the cranial and the caudal facet joint surfaces flattened with increasing age. The group with the older patients had significant lower facet joint angles than the group with the younger patients. CONCLUSION: In conclusion, it should be taken into consideration, how the design of an artificial cervical disc needs to be adapted for a vertebral segment depending on the facet joint angle. Thus the articulation of a cervical motion segment can be optimized, so that it moves within a normal physiological manner.

Anatomical study of preganglionic spinal nerve and disc relation at different lumbar levels: Special aspect for microscopic spine surgery.

BACKGROUND: Lumbar microdiscectomy is a widespread popular method of treatment. One major challenge is the spine level dependent different anatomy and the limited sight on the nerve root during the surgical procedure. OBJECTIVE: The aim was to analyze the specific anatomic relation of nerve root, intervertebral disc and intervertebral ganglion under determination of the specific nerve distances. Furthermore the relation between the disc and the corresponding nerve root was evaluated. METHODS: Regular human lumbar spine specimens of body donors were included in the study. Microscopic assisted dissection was performed. The topographical distances between a defined disc measurement point (DP) and the corresponding nerve root shoulder (NS) were measured. The preganglionic distance from the caudal axilla point (AP) of the spinal nerve root and the center point (CG) of the spinal ganglion in the intervertebral foramen were determined. RESULTS: The AP-CG distance increased gradually in the caudal direction from L1 (7.25 ± 2.72 mm right side, 7.30 ± 2.85 mm left side) to a maximum for L5 (16.00 ± 3.39 mm right side, 16.50 ± 3.58 mm left side, p< 0.05). We found a significant reduction for S1 (14.88 ± 3.42 mm right side, 13.83 ± 2.47 mm, p< 0.05). In contrast the DP-AP distances showed a maximum for L1 (12.75 ± 2.78 mm right side, 13.70 ± 3.87 mm left side) with an increasing shortening in the caudal direction and even negative values for S1 (-2.63 ± 3.31 mm right side, -0.83 ± 2.84 mm left side, p< 0.01). CONCLUSION: The topographical anatomy changes each lumbar segment and demands therefore an exact preoperative planning using this specific knowledge to perform a successful microscopic spine surgery. The results of the study support a better understanding of the relevant anatomy and help to reduce incomplete herniated disc removal and to avoid surgical complications.

Intrathecal volume changes in lumbar spinal canal stenosis following extension and flexion: An experimental cadaver study.

BACKGROUND: The spinal canal stenosis is a common disease in elderly. The thecal sac narrowing is considered as the anatomical cause for the disease. There is evidence that the anatomical proportions of the lumbar spinal canal are influenced by postural changes. The liquor volume shift during these postural changes is a valuable parameter to estimate the dynamic qualities of this disease. OBJECTIVE: The aim of this human cadaver study was the determination of intrathecal fluid volume changes during the lumbar flexion and the extension. A special measuring device was designed and built for the study to investigate this issue under controlled conditions. METHODS: The measuring apparatus fixed the lumbar spine firmly and allowed only flexion and extension. The dural sac was closed water tight. The in vitro changes of the intrathecal volumes during the motion cycle were determined according to the principle of communicating vessels. Thirteen human cadaver spines from the Institute of Anatomy were examined in a test setting with a continuous adjustment of motion. The diagnosis of the lumbar spinal stenosis was confirmed by a positive computer tomography prior testing. The volume changes during flexion and extension cycles were measured stepwise in a 2 degree distance between 18° flexion and 18° extension. Three complete series of measurements were performed for each cadaver. RESULTS: Two specimens were excluded because of fluid leaks from further investigation. The flexion of the lumbar spine resulted in an intrathecal volume increase. The maximum volume effects were seen in the early flexion positions of 2° and 4°. The spine reclination resulted in a volume reduction. The maximum extension effect was seen between 14° and 16°. CONCLUSION: According to our results, remarkable volume effects were seen in the early movements of the lumbar spine especially for the flexion. The results support the concept of the spinal stenosis as a dynamic disease and allow a better understanding of the pathophysiology of this nosological entity. Under clinical aspects our data support the value of a body upright position under avoiding of extended spinal inclination and reclination.