Medial swivel dislocation with impacted navicular bone into the talar head: A case report.

Medial swivel dislocation is a rare subtype of midtarsal bone dislocation, mostly associated with fracture rather than isolated dislocation. It is caused by medially or laterally direct forces to the midfoot. In case of failed closed reduction of the deformity, the patient should undergo open reduction and stabilization of the injury as soon as possible. We are presenting a 17-year-old, male, who sustained a left ankle injury and presented with a deformity, closed reduction of the deformity failed multiple times, and the patient was taken for open reduction and stabilization of the deformity in the operating theater. Intra-operatively, the dislocation was locked with the lateral process of the navicular being impacted into the taller head. Six months following the injury the patient was back to his pre-injury status and did not have any recurrent dislocation of the midfoot.

Isolated myeloid sarcoma of the tibia: A case report.

INTRODUCTION: Myeloid sarcoma (MS) is a rare extramedullary tumor composed of malignant myeloid cells that most commonly arise in patients previously diagnosed with myeloproliferative disease. However, they can still occur in isolation and without bone marrow disease. CASE PRESENTATION: An 8-year-old girl who had a history of acute myeloid leukemia and was off treatment for four years presented to the clinic with a history of on and off left knee swelling and pain without any direct trauma to the knee over the last two years. Knee Magnetic resonance imaging (MRI) showed diffused joint effusion with proximal tibia focal edema. A diagnosis of juvenile rheumatoid arthritis was suspected, and the patient was started on treatment, but the problem did not resolve. Eventually, the patient underwent a repeat MRI and showed increased joint effusion with an increase in the focal edema. An open bone biopsy of the lesion was taken, and the histopathology showed sheets of primitive mononuclear cells positive for CD33 and CD117 and negative for CD34, myeloperoxidase, CD10, CD20, and CD68, indicating myeloid sarcoma. CLINICAL DISCUSSION: Histological examination and immunohistochemistry are the most important in diagnosing myeloid sarcoma. Previously, before the introduction of chemotherapy and stem cell transplant, such cases of proximal tibia MS were treated with surgical resection of the bone. However, chemotherapy with the possibility of an allogeneic hematopoietic stem cell transplant (alloHSCT) has changed the view of survival in such cases. CONCLUSION: Isolated proximal tibia myeloid sarcoma is a rare occurrence that can be misdiagnosed and lead to delayed treatment. Bone biopsy, Immunohistochemistry, and cytogenetic studies play a critical role in differentiating MS from other types of tumors.

Gluteal compartment syndrome secondary to prolonged immobilization following carbon monoxide poisoning associated with leukoencephalopathy: A case report.

Introduction: Gluteal compartment syndrome (GCS) is a rare diagnosis that results mostly from a non-traumatic etiology. We describe a case of a gluteal compartment syndrome, complicated with sciatic nerve palsy. Case presentation: This paper reported a case of gluteal compartment syndrome caused by prolonged immobilization due to carbon monoxide poisoning. The case was complicated with sciatic nerve palsy and a sequala of leukoencephalopathy. Discussion and conclusion: This case report highlighted the importance of having a high suspicion for gluteal compartment syndrome in patients with history of lying down with prolonged immobilization. The diagnosis can be made solely on clinical examination and a fasciotomy must be performed with no delay.

Disability-adjusted life years from bone and joint infections associated with antimicrobial resistance: an insight from the 2019 Global Burden of Disease Study.

PURPOSE: Bone and joint infections, complicated by the burgeoning challenge of antimicrobial resistance (AMR), pose significant public health threats by amplifying the disease burden globally. We leveraged results from the 2019 Global Burden of Disease Study (GBD) to explore the impact of AMR attributed to bone and joint infections in terms of disability-adjusted life years (DALYs), elucidating the contemporary status and temporal trends. METHODS: Utilizing GBD 2019 data, we summarized the burden of bone and joint infections attributed to AMR across 195 countries and territories in the 30 years from 1990 to 2019. We review the epidemiology of AMR in terms of age-standardized rates, the estimated DALYs, comprising years of life lost (YLLs) and years lived with disability (YLDs), as well as associations between DALYs and socio-demographic indices. RESULTS: The GBD revealed that DALYs attributed to bone and joint infections associated with AMR have risen discernibly between 1990 and 2019 globally. Significant geographical disparities and a positive correlation with socio-demographic indicators were observed. Staphylococcus aureus infections, Group A Streptococcus, Group B Streptococcus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterobacter-related bone and joint infections were associated with the highest DALYs because of a high proportion of antimicrobial resistance. Countries with limited access to healthcare, suboptimal sanitary conditions, and inconsistent antibiotic stewardship were markedly impacted. CONCLUSIONS: The GBD underscores the escalating burden of bone and joint infections exacerbated by AMR, necessitating urgent, multi-faceted interventions. Strategies to mitigate the progression and impact of AMR should emphasize prudent antimicrobial usage and robust infection prevention and control measures, coupled with advancements in diagnostic and therapeutic modalities.

The role of patient positioning in surgical fixation of the calcaneus fractures using the lateral extensile approach.

INTRODUCTION: Calcaneus is the most commonly fractured tarsal bone. Open reduction and internal fixation of the displaced intra-articular fractures is considered the gold standard treatment. The lateral extensile approach is the most commonly used approach, and usually, the patients are kept in lateral decubitus position. Recent study has descried calcaneus fracture fixation utilizing the lateral extensile approach with the patient in prone position. The aim of this study was to compare the postoperative radiological outcome, reoperation rate, operative and anesthesia time, infection and the wound complications rate between the two groups. METHODS: The data of 49 adult patients with unilateral closed calcaneus fracture underwent open reduction and internal fixation using lateral extensile approach were collected. Postoperative Bohler's, Gissane angles and complications rate were compared between the two groups. RESULTS: A total of 49 patients were included. Lateral position was utilized in 26 patients (53.1%), while 23 patients (46.9%) were operated in prone position. Majority of the patients were males 87.8% (43 patients), and the mean age of the patients was 31.12 ± 7.50. The most commonly mechanism of injury was fall from height in (91.8%) of the patients. The mean preoperative Bohler's angle was 9.33 ± 13.07 and increased to 22.69 ± 9.15 postoperatively. The mean preoperative angle of Gissane was 130.45 ± 26.98 whereas it was 124.76 ± 17.20 postoperatively. The mean postoperative Bohler's angle and angle of Gissane were significantly higher among patient who underwent fixation in lateral position (25.88 ± 6.62, 137.15 ± 11.17) when compared to the prone one (19.09 ± 10.35, 110.74 ± 10.81). There was no significant difference between the two groups regarding the reoperation rate (p 0.947), infection (p 0.659, operative time (p 0.688), anesthesia time (p 0.522) and wound complications (p 0.773). CONCLUSION: Surgical restoration of the Bohler's and Gissane's angles with the patient placed in the lateral decubitus position remains superior to the prone position with no difference in the complication rate between the two groups.

Correlation between anthropometric measurements and graft size in anterior cruciate ligament reconstruction: a systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis aimed to investigate the correlation between anthropometric measurements and graft size in anterior cruciate ligament (ACL) reconstruction. METHODS: A systematic search of Ovid MEDLINE, Embase, and Cochrane Library databases was conducted for observational studies published until March 2023 that reported the relationship between anthropometric data [height, weight, body mass index (BMI), age, gender, thigh length, and circumference] and ACL graft size. Correlation coefficients (COR) and their associated 95% confidence intervals were used as the primary effect size. This review was conducted in line with PRISMA guidelines. RESULTS: A total of 42 observational studies involving 7110 patients were included, with a mean age of 29.8 years. Statistically significant, moderately positive correlations were found between graft size and height (COR: 0.49; 95% CI: 0.41-0.57; p-value: < 0.001), weight (COR: 0.38; 95% CI: 0.31-0.44; p-value: < 0.001), thigh circumference (COR: 0.40; 95% CI: 0.19-0.58; p-value: < 0.001), and thigh length (COR: 0.35; 95% CI: 0.18-0.50; p-value: < 0.001). However, age and gender were insignificantly correlated with graft size (p-value: NS). A subanalysis based on graft type showed a significant positive correlation between height and graft diameter, which was more significant in the peroneus tendon than in hamstring grafts (COR: 0.76 vs. 0.45; p-value: 0.020). CONCLUSION: This study demonstrated a moderate positive correlation between anthropometric measurements (height, weight, thigh circumference, and length) and ACL graft size, along with a weak positive correlation with BMI. Age and gender showed no significant correlation. These findings support the predictability and selection of ACL graft size based on pre-operative patient anthropometric data. LEVEL OF EVIDENCE: Level of Evidence: IV. PROSPERO registration number: CRD42023416044.

Vanishing solitary osteochondroma of humerus following trauma: A case report.

Osteochondromas are the most common benign tumors of the bone. Mainly these lesions affect the long-bone metaphysis and usually are asymptomatic. When complications develop from these lesions, then they become symptomatic and surgical resection may become indicated. Spontaneous resolution of osteochondroma is rare. There have been fewer case reports about this condition. We are reporting 16 years old, male, who sustained direct trauma to his shoulder and presented with fracture at the base of a solitary osteochondroma. Complete resolution of the lesion occurred without any surgical intervention 18 months following the fracture.

Bilateral pelvic crescent fracture combined with left acetabular fracture: A case report.

INTRODUCTION: Crescent fracture-dislocations are subtype of lateral compression fractures of the pelvic ring, which usually occur following high-velocity impacts. Bilateral crescent fractures are rare entities, with a limited number of cases reported in the literature. Of those reported, none were combined with an acetabulum fracture. PRESENTATION OF CASE: The case involves a 49-year-old male, who presented to the trauma unit after a motor vehicle collision and sustained a bilateral crescent pelvic fracture combined with a left acetabulum fracture. The patient was resuscitated and managed initially according to the advanced trauma life support (ATLS) protocol then staged fixation of his pelvic and acetabulum fractures was carried out. CONCLUSION: Bilateral crescent fractures of the pelvis combined with acetabulum fractures constitute a rare injury. Given their rarity, a standard of care is lacking and has not been described yet. Staged surgical stabilization of such combined injuries is recommended, and may contribute to a better outcome.

Appropriateness of carpal tunnel syndrome management compared with the AAOS appropriate use criteria: A retrospective review across various specialties.

Purpose: Carpal tunnel syndrome (CTS) is a common peripheral nerve entrapment disorder among adults that causes upper-extremity disability. The American Academy of Orthopedic Surgeons (AAOS) developed an evidence-based appropriate use criteria (AUC) for the management of CTS. This study aimed to assess the appropriateness of our practice and the usability of the AUC through comparing the actual management provided at our institution with that recommended by the AUC. Methods: A retrospective review of the electronic medical records at our hospital was performed between 1 Jan 2016 and 31 Dec 2019. Data were collected by two authors independently. The collected data were input into the AUC application to determine the rate of the appropriateness of the treatments. Afterwards, the agreement between the actual treatment provided and the AUC recommendation was assessed. The primary outcome was the appropriateness rate. Descriptive statistics such as the mean, range and percentage were used to summarize the patients' demographics and treatment options. Results: There were 127 patients (169 interventions), with a mean age of 50.18 years (range, 24-85 years). Most of the included patients were females, 78% (99). Obesity was the most frequent risk factor 64.5% (82), and bilateral wrist involvement was the most common presentation 58% (74). The overall appropriateness rate and agreement with the AUC recommendations among all interventions was 84%. A sub-analysis of carpal tunnel surgical release across different surgical specialities showed appropriateness rates of 88%, 89%, 54% in orthopaedic surgery, neurosurgery and plastic surgery teams, respectively (Chi2 19.54, P-Value 0.000613). Conclusion: This study demonstrated that most of the treatments provided at our institution were appropriate and in agreement with the AUC recommendations. Additionally, the AUC for carpal tunnel syndrome is a valuable and practical tool that can be applied in clinical settings. Level of evidence: Retrospective study, level IV.

Rare presentation of intra-spinal extradural grade 1 chondrosarcoma: A case report.

INTRODUCTION: Lumbar Spine Chondrosarcomas are rare entities that accounts for less than 10% of all spinal Chondrosarcomas, patients can present with symptoms of nerve root irritation secondary to direct compression caused by the tumor mass effect. Radiologically these tumors are destructive in nature with soft tissues classifications, and the treatment of choice for it is complete surgical excision, however in some scenarios they are difficult to access and complete resection becomes not feasible. PRESENTATION OF CASE: A 37 years old male, presented to our spine clinic with chief complaint of chronic low back pain with radicular symptoms, normal power in both lower limbs, while his radiological evaluation showed intra-spinal extra-dural Chondrosarcoma arising from the posterior cortex of the 5th vertebral body, for which he underwent surgical decompression of the lumbar canal with resection of the lesion and unilateral stabilization of the spinal segment. CONCLUSIONS: Unlike Chondrosarcomas of the appendicular skeleton, lesions arising in the spinal element may be difficult to detect on plain radiographs and further imaging is crucial for better evaluation, as this will help in surgical planning for excision of the tumor. In difficult cases with inaccessible locations, marginal excision of spinal Chondrosarcomas can be achieved utilizing a minimally invasive technique with preservation of some spine motion with acceptable clinical outcomes.

The Impact of Prior Bariatric Surgery on Outcomes After Spine Surgery: A Systematic Review and meta-Analysis.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVE: To compare outcomes and complication rates in patients undergoing bariatric surgery (BS) prior to spine surgery. METHODS: A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines comparing the outcomes of spine surgery between subjects with prior bariatric surgery to those who were considered obese with no prior bariatric surgery. RESULTS: A total of 183, 570 patients were included in the 4 studies meeting inclusion criteria. The mean patient age was 52.9 years, and the majority were female (68%). The two groups consisted of a total of 36, 876 patients with prior BS and 146, 694 obese patients without prior BS. The overall rate of complications in the prior BS group was 6.4% (4.5%-38.7%) compared to 11.9% (11.2%-55.4%) in the non-prior BS obese group with a statistically significant difference between the two groups. The prior BS group had lower rates of renal, neurological, and thromboembolic complications, with a lower mortality and readmission rate. In a subgroup undergoing cervical spine surgery, patients with prior BS had fewer cardiac, GI, and total complications. For patients undergoing thoracolumbar spine surgery, patients with prior BS had fewer thromboembolic and total complications. CONCLUSION: Patients undergoing bariatric surgery prior to spine surgery had fewer renal, neurological, and thromboembolic complications as well as a decreased mortality and readmission rate.

Bilateral femoral neck fracture following a convulsion in the presence of chronic kidney disease. A case report.

INTRODUCTION AND IMPORTANCE: Bilateral femoral neck fractures in young adults are a rare entity. It is usually associated with pre-existing metabolic diseases, such as osteoporosis, renal osteodystrophy, or hypocalcemic seizures. Hence, it is essential in such cases to look for other associated injuries following a traumatic event. Missing associated injuries may lead to significant morbidities and poor functional outcomes. CASE PRESENTATION: A 37 years old male, who had chronic renal failure secondary to hypertension, and presented to the emergency room following a seizure episode, in which he developed a generalized tonic-clonic convulsion secondary to electrolyte imbalances with metabolic acidosis. As a result, he developed bilateral neck of femur fracture. INTERVENTION AND OUTCOME: The medical team optimized electrolytes imbalance and then the patient underwent surgical stabilization of both femur neck fracture, 1 year following the surgical fixation the patient had full range of motion of both hips with radiological evidence of complete healing of the fracture. CONCLUSION: In cases of fractures secondary to metabolic conditions, bilateral femoral neck fractures should be suspected and investigated; especially in young patients who develop a generalized tonic-clonic seizure. The etiology is multifactorial, and the treating surgeon should be aware of predisposing factors which may affect bone quality, thereby raising the risk of fractures even with low-energy atraumatic events. Hip preservation should always be the primary target when treating these patients.

Clinical characteristics, injury pattern and management of pediatric pelvic fracture: An observational retrospective study from a level I trauma center.

BACKGROUND: Pediatric pelvic fractures (PPF) are uncommon among children requiring hospitalization after blunt trauma. The present study explored our experience for the prevalence, patients demographics, clinical characteristics, injury pattern and management of pediatric pelvic fractures in a level I trauma center. METHODS: This is a retrospective review of prospectively collected data obtained from trauma registry database for all pediatrics trauma patients of age ≤18 years. Data were analyzed according to different aspects relevant to the clinical applications such as Torode classification for pelvic ring fracture (Type I-IV), open versus closed triradiate cartilage, and surgical versus non-surgical management. RESULTS: During the study period (3 and half years), a total of 119 PPF cases were admitted at the trauma center (11% of total pediatric admissions); the majority had pelvic ring fractures (91.6%) and 8.4% had an acetabular fracture. The mean age of patients was 11.5 ± 5.7, and the majority were males (78.2%). One hundred and four fractures were classified as type I (5.8%), type II (13.5%), type III (68.3%) and type IV (12.5%). Patients in the surgical group were more likely to have higher pelvis AIS (p = 0.001), type IV fractures, acetabular fractures and closed triradiate cartilage as compared to the conservative group. Type III fractures and open triradiate cartilage were significantly higher in the conservative group (p < 0.05). Patients with closed triradiate cartilage frequently sustained spine, head injuries, acetabular fracture and had higher mean ISS and pelvis AIS (p < 0.01) than the open group. However, the rate of in-hospital complications and mortality were comparable among different groups. The overall mortality rate was 2.5%. CONCLUSION: PPF are uncommon and mainly caused by high-impact trauma associated with multisystem injuries. The majority of PPF are stable, despite the underlying high-energy mechanism. Management of PPF depends on the severity of fracture as patients with higher grade fractures require surgical intervention. Furthermore, larger prospective study is needed to understand the age-related pattern and management of PPF.

Hyperbaric oxygen therapy for the treatment of Steinberg I and II avascular necrosis of the femoral head: a report of fifteen cases and literature review.

PURPOSE: This article aimed to report a case series of pre-collapse avascular necrosis of the femoral head treated with hyperbaric oxygen and review the most recent literature on the topic. METHODS: The data from a prospectively followed registry of 15 patients with Steinberg I and II avascular necrosis of the femoral head was collected. Functional outcome, pain scores, and radiographic changes at an average follow-up of 22 months were analyzed and reported. RESULTS: Thirteen patients had satisfactory outcome at final follow-up with an average Oxford hip score of 37.3, pain scores were significantly improved at final follow-up (P < 0.001), and 26.7% of hips progressed to collapse on follow-up radiographs with no complications reported in all patients. CONCLUSION: Hyperbaric oxygen treatment for pre-collapse avascular necrosis of the femoral head is considered a safe alternative with satisfactory clinical and radiological outcomes and low complications rate.

The outcome of hyperbaric oxygen therapy versus core decompression in the non-traumatic avascular necrosis of the femoral head: Retrospective Cohort Study.

BACKGROUND: Core decompression (CD) has been used in the treatment of pre-collapse stages avascular necrosis (AVN) with good results. Hyperbaric oygen therapy (HBO) was used as a non-invasive treatment for pre-collapse stages osteonecrosis with favorable results. This study aimed to compare the outcomes of HBO versus CD in stage II of non-traumatic AVN of the femoral head. METHODS: Data were collected retrospectively for patients with non-traumatic AVN of the femoral head that was confirmed by MRI and underwent HBO or CD between January 2010 and December 2018, with a minimum follow-up of 12 months. Oxford Hip Score (OHS), radiographic progression, and Short-Form 12(SF12) were used to assess the outcomes. RESULTS: Nineteen patients with 23 stage II AVN of the femoral head were included, 12 (52.2%) in CD, and 11 (47.8%) in the HBO group with an average follow-up of 34.2 ± 18.4 months.66.7% of patients in CD and 81.8% in the HBO group achieved satisfactory hip function outcome with statistically significant mean Oxford Hip Score (35.8 ± 6.7 and 35.5 ± 5.1) (P 0.009 & .003) respectively.No statistical difference of OHS and SF12 (PCS &MCS) was found between the two groups (P 0.202, 0.128 & .670 respectively).Eight (34.7%) cases progressed to a higher radiological stage at one year follow-up. The rate of progression was not statistically significant between both groups (P 0.469) with no statistical difference of OHS and SF12 (PCS & MCS) in the progressed group (P 0.747, 0.648 & 0.416) respectively. CONCLUSION: This study showed that the HBO is promising and as effective as CD in the treatment of non-traumatic pre-collapsed AVN of the femoral head. Hence, HBO could be used as an alternative non-invasive treatment option.

Anthropometric correlation with hamstring graft size in anterior cruciate ligament reconstruction among males.

PURPOSE: Pre-operative knowledge of hamstring graft size for anterior cruciate ligament reconstruction (ACL) is of clinical importance and useful in making appropriate decisions about graft choice. This study investigated if there is any correlation between anthropometric measurements such as height, weight, body mass index, thigh length, and circumference with the size of hamstring tendon graft in anterior cruciate ligament reconstruction. METHODS: The anthropometric data of 50 consecutive adult males, who underwent primary ACL reconstruction using quadruple hamstring autograft, were collected prospectively. Data analysis using Pearson's correlation test was performed and multiple logistic regression analysis was used to investigate any correlation not detected by Pearson's test and to eliminate confounders. RESULTS: Patient's height and thigh length demonstrated a positive correlation with gracilis graft length (r = .464, P = .001, r = .456, P = .001, respectively) and semitendinosus graft length (r = .541, P = 000, r = .578, P = .000, respectively). While the patient's age was the only independent factor which had a positive correlation with the quadrupled hamstring graft diameter (r = .412, P = .004), multiple regression analysis showed abdominal girth had a significant negative correlation with gracilis (P = .04) and semitendinosus (P = .006) graft thickness. CONCLUSION: This study demonstrated that some anthropometric measurements had a positive correlation with the hamstring graft length and diameter in male patients. Hence, these results provide preliminary support for the use of some anthropometric measurements in the preoperative planning and prediction of the hamstring graft length and diameter in anterior cruciate ligament reconstruction.

Functional and Radiological Outcomes of Combined Anterior-Posterior Approach Versus Posterior Alone in Management of Isthmic Spondylolisthesis. A Systematic Review and Meta-Analysis.

BACKGROUND: Lumbar isthmic spondylolisthesis (IS) in adults is defined as the forward slippage of a vertebra onto the top of the vertebra, resulting from a defect in the pars intraarticular, and can be low grade or high grade. Persistent back pain or neurological deficit are indications for surgical intervention. Surgery can be done from back, front, or both, with or without fusion, instrumentation, or decompression, and short or long segment. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, several databases were searched through August 2017 for any observational or experimental studies that evaluated combined anterior-posterior approach versus posterior alone in management of IS. Primary outcome was fusion rate, whereas secondary outcomes included functional outcomes (Visual Analogue Scale [VAS] and Oswestry Disability Index [ODI] score), complication rate (infection, neurological), and reoperation rate. Descriptive, quantitative, and qualitative data were extracted. Most of the cases were low-grade IS. RESULTS: Of the 645 articles identified, 6 studies were eligible for the meta-analysis, with a total of 397 patients with IS, 198 in the combined (anterior interbody fusion [ALIF] + postero-lateral fusion [PLF]) group and 199 in the posterior (transformational interbody fusion [TLIF]/ postero-lateral interbody fusion [PLIF] + PLF) group, average age of 47.2 years, and 185:212 male : female ratio. Although the fusion rate reached 100% in some studies, the pooled odds ratio (OR) of fusion rate (OR = 1.02, 95% confidence interval [CI]: 0.294, 3.552, P = .972) did not reach statistical significance between (ALIF + PLF) versus (TLIF/PLIF + PLF). The estimated pooled standardized mean difference (SMD) showed less blood loss in the anterior approach compared to the posterior approach (SMD = -0.528, 95% CI: -0.777, -0.278, P < .001), with no difference in operative time and length of hospital stay. Despite both groups showing significant improvement in pain and functional scores at final follow up, ODI and VAS were not significantly different between groups with ODI (SMD = -0.644, 95% CI: -1.948, 0.621, P = .311) and VAS (SMD = 0.113, 95% CI: -0.173, 0.400, P = .439). The complication rate for the anterior approach was higher than the posterior, whereas reoperation rate was higher in the posterior approach than the anterior. CONCLUSIONS: No significant difference between anterior and posterior approaches was found in the global assessment of fusion rate and clinical outcomes, despite a higher rate of complications using the anterior approach. LEVEL OF EVIDENCE: 3. CLINICAL RELEVANCE: Both anterior and posterior approach are a valid option for treatment of isthemic spondylolisthesis.