Bilateral Femoral Neck Pseudarthrosis in an Adolescent Girl With Congenital Spondyloepiphyseal Dysplasia. The Treatment Journey: A Case Report.

CASE: We describe the surgical management of a girl with dwarfism and congenital spondyloepiphyseal dysplasia, who presented in adolescence with coxa vara and bilateral pseudarthrosis between the femoral neck and the diaphysis, with asymmetric distal migration at both sites and leg length discrepancy. The patient at 16 years underwent valgus osteotomy in situ and femoral neck fixation in the left hip. The right hip was operated 19 months later. CONCLUSION: Hip dysplasia is common in spondyloepiphyseal dysplasia, but a debilitating nontraumatic bilateral pseudarthrosis at the base of the femoral neck has not been previously reported. Valgus corrective osteotomies of the femur in situ led to union and allowed the patient to walk.

Radiological and Clinical Outcomes of Transforaminal vs. Posterior Lumbar Interbody Fusions: A Systematic Review.

AIM: To compare 1 and 2 level posterior lumbar interbody fusion (PLIF) to transforaminal lumbar interbody fusion (TLIF) techniques in an effort to elucidate trends in overall radiological and clinical outcome, rate of complications, operation time, length of hospital stay, reoperation rate, pseudoarthrosis or failure rate, and estimated blood loss. MATERIAL AND METHODS: Online databases including Scopus, Science Direct, Clinical key, Ovid, Embase, and PubMed/ Medline were queried over the period encompassing January 2000 to August 2021 for suitable studies. Search criteria consisted of ("TLIF" AND "PLIF") OR ("Transforaminal Lumbar interbody fusion" AND "Posterior lumbar interbody fusion") AND ("comparative" OR "comparison") OR ("fusion" OR "outcome" Or "reoperation" OR "Failure rate" OR "Failure" OR "Complication rate" OR "Complication"). RESULTS: Fourteen eligible studies were selected. Neurological deficits were considerably higher in the PLIF group (24%vs.10%). The mean operation time and estimated blood loss for PLIF and TLIF were 178.5 min and 515 ml; and 160 min and 405 ml, respectively. No significant difference was found regarding the fusion rate. The reoperation rate was greater in PLIF (2%) than TLIF (0%). No clear difference was found regarding the length of stay (LOS) and surgical site infection (SSI). CONCLUSION: The superiority of TLIF over PLIF may be evidenced by the lower rate of neurologic deficit, surgical technical aspects, less blood loss and shorter operation time. Cage migration, screw displacement, infection, and pseudoarthrosis may be influenced by a variety of factors, including the facility, the surgeon, and the instrumentation/ graft used, and do not appear to be different. Multicenter non-randomized prospective trials are recommended to determine the possible superiority of one method over the other.

Clinical Observation of Posterior Approach for Surgical Treatment of Thoracolumbar Pseudarthrosis in Ankylosing Spinal Disorders.

OBJECTIVE: The objective of this study was to evaluate the surgical effectiveness of posterior procedure with long segment stabilization for treating thoracolumbar pseudarthrosis associated with ankylosing spinal disorders (ASDs) without anterior fusion or osteotomy. METHODS: Twelve patients with thoracolumbar pseudarthrosis in ASD were enrolled. All patients underwent posterior long-segment stabilization procedures. In some patients, the percutaneous technique or the aid of a robot or O-arm navigation was utilized for pedicle screw implantation. The clinical results were evaluated by means of the visual analog scale and Oswestry Disability Index. Radiological outcomes were evaluated for bone fusion, anterior column defect, local kyphotic correction, and position of the pedicle screws. RESULTS: All patients experienced effective bone fusion at the sites of pseudarthrosis. The mean operative time was 161.7 ± 57.1 minutes, and the average amount of blood loss was 305.8 ± 293.2 mL. For 6 patients who underwent surgery with the assistance of a robot or O-arm navigation, there was no statistically significant difference observed in terms of operative time and mean blood loss compared to those who used the freehand technique (P > 0.05). The visual analog scale score, Oswestry Disability Index value, and mean local kyphotic angle showed significant improvements at the final follow-up (P < 0.05). The accuracy of pedicle screw placement was 96%. CONCLUSIONS: Posterior surgery with long-segment fixation, without anterior fusion or osteotomy, can achieve satisfactory outcomes in ASD patients with thoracolumbar pseudarthrosis. The application of percutaneous techniques, as well as the assistance of robots or navigation technique may be a good choice for the treatment of pseudarthrosis in ASD patients.

Postoperative CT imaging to characterize fusion in pediatric and adolescent vertebral column resection.

BACKGROUND: Vertebral column resection (VCR) is a powerful corrective technique for the management severe, rigid spinal deformities but does carry a relatively high complications rate. One of the feared complications is pseudarthrosis which places the patient at risk for implant failure. We present a single-center experience with post-operative computed tomography (CT) imaging at the osteotomy site to screen for impending pseudarthrosis. METHODS: A retrospective review of a single surgeon series of posterior-only VCR performed for severe pediatric and adolescent spinal deformities was performed. Demographic, radiographic, and clinical data were collected. Patients underwent postoperative CT imaging at the osteotomy site 6-9 months following VCR with grading of the osteotomy fusion. Patients with impending pseudarthrosis were recommended for prophylactic revision surgery. RESULTS: Thirty-three patients were included (mean age 11.6 ± 4.9 years, 54.5% female), undergoing a mean 1.9 level VCR. Kyphoscoliosis accounted for 75.7% (N = 25/33) of cases with 45.5% of all cases being congenital etiology and 60.6% having at least 1 previous surgery. Postoperative CT imaging was performed in 22 patients at a mean of 7.8 months following VCR. Two patients were identified as having impending pseudarthrosis with one undergoing revision surgery to enhance the posterior fusion, with addition of a third rod while one patient refusing surgery who subsequently developed broken hardware requiring revision surgery. No patient with a stable fusion on CT imaging developed a clinically significant pseudarthrosis. DISCUSSION: Postoperative CT imaging of the osteotomy is useful in screening for impending pseudarthrosis and can aide in decision making for clearance to return to activity or the need for prophylactic intervention following VCR in pediatric and adolescent patients. We advocate that obtaining routine CT imaging of the osteotomy site at 6-9 months may identify potential complications earlier and allow for prophylactic intervention.

Long-term outcomes in patients treated with tissue-sparing posterior cervical fusion to revise a 1-level pseudarthrosis following ACDF.

STUDY DESIGN: Observational Study BACKGROUND: Symptomatic pseudarthrosis is one long-term complication in patients treated with anterior discectomy and fusion (ACDF). When revising a pseudarthrosis, a surgeon must decide to intervene posteriorly and/or anteriorly. Open posterior cervical fusion (PCF) is attractive for high rates of arthrodesis, however this technique introduces risks of added complications resulting from extensive soft tissue dissection. The purpose of this study was to assess long-term outcomes in patients undergoing tissue-sparing PCF with facet instrumentation to treat a single level pseudarthrosis. METHODS: Forty-five subjects were recruited from six participating sites. All subjects had a history of ACDF that was subsequently revised with tissue-sparing PCF to treat symptomatic pseudarthrosis at one level. Long-term radiographic assessments included flexion and extension X-ray and multi-planar CT. Subjects additionally completed a patient satisfaction questionnaire. Radiographs were assessed by investigators and an independent core imaging lab to diagnose implant integrity and arthrodesis at the revised levels. RESULTS: The revision procedure required a median 49 min to complete with an estimated blood loss of 10 cc. Subjects were discharged a median 1 day following treatment. There were no instances of hospital re-admission nor subsequent surgical interventions. Study follow-up assessments were performed a median 39 months from revision. Surgeons diagnosed complete fusion in 91 % of cases. The core imaging lab identified bridging bone across the revised segment in 80 % of cases. Range of motion was < 2° in 93 % of cases. Seventy-four percent of subjects reported being satisfied with their outcomes. CONCLUSIONS: This study summarizes long-term radiographic outcomes in a cohort of patients receiving tissue-sparing PCF for the treatment of pseudarthrosis. Assessed years after revision, patients achieved rates of arthrodesis similar to open PCF without the soft tissue dissection responsible for perioperative morbidity and long-term soft tissue pain.

Rib pseudoarthrosis with thoracic outlet syndrome in pediatric gymnast: a case report.

BACKGROUND: This case study evaluates the diagnosis and treatment of a 12 year old Caucasian male gymnast who had several diagnoses including an isolated first rib fracture, resultant pseudoarthrosis of the first rib, and the development of symptomatic thoracic outlet syndrome. We discuss the causes, prevalence, and suggestions for prompt diagnosis and treatment of these conditions in pediatric patients. Although all three conditions are rare in a child, this case highlights the importance of having a high clinical index of suspicion in recurrent pain in pre-pubertal athletes. CASE PRESENTATION: A 12 year old Caucasian male underwent several years of conservative treatment with physical therapy and rest without resolution of his left shoulder pain. He was subsequently diagnosed with pseudoarthrosis of the first rib and thoracic outlet syndrome, which was curative by surgical removal of the first rib, and allowed him to return to his baseline activity level. CONCLUSIONS: Since each of these diagnoses are rare, especially in the pediatric population, we aim to educate the medical community on the prompt diagnosis and treatment of these conditions.

Impact of the adjacent bone on pseudarthrosis in mandibular reconstruction with fibula free flaps.

BACKGROUND: Mechanical and morphological factors have both been described to influence the rate of pseudarthrosis in mandibular reconstruction. By minimizing mechanical confounders, the present study aims to evaluate the impact of bone origin at the intersegmental gap on osseous union. METHODS: Patients were screened retrospectively for undergoing multi-segment fibula free flap reconstruction of the mandible including the anterior part of the mandible and osteosynthesis using patient-specific 3D-printed titanium reconstruction plates. Percentage changes in bone volume and width at the bone interface between the fibula/fibula and fibula/mandible at the anterior intersegmental gaps within the same patient were determined using cone-beam computed tomography (CBCT). Additionally, representative samples of the intersegmental zones were assessed histologically and using micro-computed tomography (µCT). RESULTS: The bone interface (p = 0.223) did not significantly impact the change in bone volume at the intersegmental gap. Radiotherapy (p < 0.001), time between CBCT scans (p = 0.006) and wound healing disorders (p = 0.005) were independent risk factors for osseous non-union. Preliminary analysis of the microstructure of the intersegmental bone did not indicate morphological differences between fibula-fibula and fibula-mandible intersegmental bones. CONCLUSIONS: The bone interface at the intersegmental gap in mandibular reconstruction did not influence long-term bone healing significantly. Mechanical and clinical properties seem to be more relevant for surgical success.

Pseudarthrosis after four-level anterior cervical discectomy and fusion without posterior fixation.

OBJECTIVE: Fusion rates and long-term outcomes are well established for anterior cervical discectomy and fusion (ACDF) of 3 levels or fewer, but there is a paucity of similar data on 4-level fusions. The authors evaluated long-term fusion rates and clinical outcomes after 4-level ACDF without supplemental posterior instrumentation. METHODS: The authors retrospectively reviewed patients who underwent 4-level ACDF at a single institution with at least 1-year of radiological follow-up. Fusion was determined by measuring change in interspinous distance at each segment on dynamic radiographs or by the presence of bridging bone on CT scans at minimum 1-year follow-up. Clinical outcomes were assessed using Neck Disability Index and Short Form-36. RESULTS: A total of 63 patients (252 levels) met the inclusion criteria for the study, with a mean follow-up of 2.6 years. Complete radiographic fusion at all 4 levels was observed in 26 patients (41.3%). Of the 37 patients (58.7%) with radiographic pseudarthrosis, there was a mean of 1.35 nonfused levels. The fusion rate per level, however, was 80.2% (202/252 levels). The most common level demonstrating nonunion was the distal segment (C6-7), showing pseudarthrosis in 29 patients (46.8%), followed by the most proximal segment (C3-4) demonstrating nonunion in 9 patients (14.5%). The mean improvement in Neck Disability Index and Short Form-36 was 15.7 (p < 0.01) and 5.8 (p = 0.14), respectively, with improvement in both scores surpassing the minimum clinically important difference. One patient (1.6%) required revision surgery for symptomatic pseudarthrosis, and 5 patients (7.9%) underwent revision for symptomatic adjacent-segment disease. Patient-reported outcomes results are limited by the low rate of 1-year follow-up (50.8%), whereas reoperation data were available for all 63 patients. CONCLUSIONS: More than half of patients undergoing 4-level ACDF without posterior fixation demonstrated pseudarthrosis of at least 1 level-most commonly the distal C6-7 level. One patient required revision for symptomatic pseudarthrosis. Patient-reported outcomes showed significant improvements at 1-year follow-up, but clinical follow-up was limited. This is the largest series to date to evaluate fusion outcomes in 4-level ACDF.

Postoperative cage migration and subsidence following TLIF surgery is not associated with bony fusion.

Pseudarthrosis following transforaminal interbody fusion (TLIF) is not infrequent. Although cage migration and subsidence are commonly regarded as evidence of the absence of solid fusion, there is still no evidence of the influence of cage migration and subsidence on fusion. This study aimed to evaluate cage migration and subsidence using computed tomography (CT) DICOM data following lumbar interbody fusion. The effects of cage migration and subsidence on fusion and clinical outcomes were also assessed. A postoperative CT data set of 67 patients treated with monosegmental TLIF was analyzed in terms of cage position. To assess the effects of cage migration and subsidence on fusion, 12-month postoperative CT scans were used to assess fusion status. Clinical evaluation included the visual analog scale for pain and the Oswestry Disability Index. Postoperative cage migration occurred in 85.1% of all patients, and cage subsidence was observed in 58.2%. Radiological signs of pseudarthrosis was observed in 7.5% of the patients Neither cage migration nor subsidence affected the clinical or radiographic outcomes. No correlation was found between clinical and radiographic outcomes. The incidence of cage migration was considerable. However, as cage migration and subsidence were not associated with bony fusion, their clinical significance was considered limited.

Pseudoarthrosis after anterior cervical discectomy and fusion: rate of occult infections and outcome of anterior revision surgery.

BACKGROUND: Pseudoarthrosis after anterior cervical discectomy and fusion (ACDF) is relatively common and can result in revision surgery. The aim of the study was to analyze the outcome of patients who underwent anterior revision surgery for pseudoarthrosis after ACDF. METHODS: From 99 patients with cervical revision surgery, ten patients (median age: 48, range 37-74; female: 5, male: 5) who underwent anterior revision surgery for pseudoarthrosis after ACDF with a minimal follow up of one year were included in the study. Microbiological investigations were performed in all patients. Computed tomography (CT) scans were used to evaluate the radiological success of revision surgery one year postoperatively. Clinical outcome was quantified with the Neck Disability Index (NDI), the Visual Analog Scale (VAS) for neck and arm pain, and the North American Spine Society Patient Satisfaction Scale (NASS) 12 months (12-60) after index ACDF surgery. The achievement of the minimum clinically important difference (MCID) one year postoperatively was documented. RESULTS: Occult infection was present in 40% of patients. Fusion was achieved in 80%. The median NDI was the same one year postoperatively as preoperatively (median 23.5 (range 5-41) versus 23.5 (7-40)), respectively. The MCID for the NDI was achieved 30%. VAS-neck pain was reduced by a median of 1.5 points one year postoperatively from 8 (3-8) to 6.5 (1-8); the MCID for VAS-neck pain was achieved in only 10%. Median VAS-arm pain increased slightly to 3.5 (0-8) one year postoperatively compared with the preoperative value of 1 (0-6); the MCID for VAS-arm pain was achieved in 14%. The NASS patient satisfaction scale could identify 20% of responders, all other patients failed to reach the expected benefit from anterior ACDF revision surgery. 60% of patients would undergo the revision surgery again in retrospect. CONCLUSION: Occult infections occur in 40% of patients who undergo anterior revision surgery for ACDF pseudoarthrosis. Albeit in a small cohort of patients, this study shows that anterior revision surgery may not result in relevant clinical improvements for patients, despite achieving fusion in 80% of cases. LEVEL OF EVIDENCE: Retrospective study, level III.

Low-Intensity Pulsed Ultrasound for Symptomatic Pseudarthrosis After Toe Fracture with Symphalangism: A Report of 2 Cases.

CASE: Distal phalangeal fractures are often treated conservatively. However, some patients experience residual pain. We report 2 cases of patients who underwent low-intensity pulsed ultrasound (LIPUS) therapy for pseudarthrosis after fracture of the distal phalanx of the fifth toe with symphalangism. Both patients (female, 63 and 33-year-old, respectively) underwent conservative treatment with buddy-taping fixation; however, bone union failed, and LIPUS therapy was initiated. In both cases, bone union was achieved and pain resolved after 3 months. CONCLUSION: Bone union occasionally fails after conservative treatment of distal phalangeal fractures. LIPUS is a useful treatment of symptomatic pseudarthrosis after such fractures.

Fate of pseudarthrosis detected 2 years after anterior cervical discectomy and fusion: results of a minimum 5-year follow-up.

BACKGROUND CONTEXT: Prior study has shown that 70% of cervical pseudarthrosis after anterior cervical discectomy and fusion (ACDF) detected at 1 year will go on to fusion by 2 year. Pseudarthrosis detected 2 years after ACDF may have different bone healing potential compared to nonunion detected 1 year after surgery. Therefore, it might have a different clinical significance. PURPOSE: To examine the radiographic and clinical prognosis of pseudarthrosis detected 2 years after ACDF with a minimum follow-up of 5 years. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENTS SAMPLE: A total of 249 patients who completed a 5-year follow-up after ACDF. OUTCOMES MEASURES: Clinical outcomes such as neck pain visual analogue scale (VAS), arm pain VAS, and neck disability index (NDI) and radiographic assessment such as X-ray, computed tomography (CT) scan. METHODS: A total of 249 patients who completed a 5-year follow-up after ACDF were retrospectively reviewed. Patients who were diagnosed with pseudarthrosis at 2 years postoperatively were included. Fusion, neck pain VAS, arm pain VAS, and NDI were assessed. The results were compared between the union group (patients who achieved union), and the nonunion group (patients with pseudarthrosis) at 5 years postoperatively. RESULTS: Among the patients who had pseudarthrosis at 2 years postoperatively, the fusion rate at 5 years was 32.6% (14/43). While the union group showed continued improvements in neck pain VAS, arm pain VAS, and NDI until 5 years, the nonunion group showed significant worsening of arm pain VAS and NDI at 5 years, with the values of neck pain VAS, arm pain VAS, and NDI being significantly worse than those of the union group at 5 years. CONCLUSION: The incidence of pseudarthrosis detected at 2 years postoperatively after ACDF was 67.4%, and it remained unfused at 5 years postoperatively. Nonunion identified 2 years after ACDF may be considered a poor prognostic factor because it has less potential to achieve fusion with further follow-up and a higher chance of worsening clinical symptoms. Therefore, the presence of fusion at the 2-year follow-up can be considered an indicator of the success of the surgery.

Thoracic Outlet Syndrome Secondary to Vascular Insufficiency from Congenital Pseudarthrosis of the Clavicle: A Case Report.

CASE: An 18-year-old woman with a history of congenital pseudarthrosis of the clavicle (CPC) presented with episodes of right upper extremity ischemia. Vascular studies demonstrated an extensive thrombus with complete occlusion of the brachial artery. She underwent urgent thrombectomy. Subsequently, she underwent first rib resection and scalenectomy as well as pseudarthrosis takedown and fixation. Postoperatively, she returned to Division I collegiate soccer with complete symptomatic resolution. CONCLUSION: We report a case of arterial thoracic outlet syndrome secondary to CPC.

[Treatment of symptomatic pseudarthrosis following acromion fracture with a patient-specific implant customized on a 3D-printed scapula]. / Versorgung symptomatischer Pseudarthrosen nach Akromionfraktur mit patientenspezifisch am 3-D-Modell angepasstem Implantat.

OBJECTIVE: Patient-specific osteosynthesis for pseudarthrosis of the acromion. INDICATIONS: Symptomatic pseudarthrosis of the acromion at the level of a meta/mesacromion. CONTRAINDICATIONS: Infection; patient noncompliance regarding postoperative treatment protocol. SURGICAL TECHNIQUE: Preoperatively, a patient-specific three-dimensional model of the scapula is printed. A locking compression plate (LCP) is individually adapted to this model. Via a dorsal surgical approach over the scapular spine, the pseudarthrosis is refreshed and autologous cancellous bone from the iliac crest is embedded in the fracture zone. This is followed by fixed-angle osteosynthesis with the individualized plate. In addition, tension banding with tapes is performed to reduce the tensile and shear forces on the fracture caused by the muscle. POSTOPERATIVE MANAGEMENT: Consistent wearing of a shoulder-arm brace for 6 weeks postoperatively, active-assisted increase in range of motion for an additional 3 weeks, then gradual increase in weight-bearing and initiation of daily activities without additional weights until 12 weeks postoperatively. RESULTS: Treatment with the presented technique resulted in radiographic consolidation of the fracture and significant improvement in range of motion and pain at the 1­year follow-up.

Association Between the Bone Density of Posterior Fusion Mass and Mechanical Complications After Thoracolumbar Three-Column Osteotomy for Adult Spinal Deformity.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To assess the relationship of fusion mass bone density on computed tomography (CT) and the development of rod fractures (RFs) and proximal junctional kyphosis (PJK). SUMMARY OF BACKGROUND DATA: Few studies have evaluated the relationship of fusion mass bone density to mechanical complications. MATERIALS AND METHODS: A retrospective review of adult spinal deformity patients who underwent thoracolumbar three-column osteotomy from 2007 to 2017 was performed. All patients underwent routine 1-year CT imaging and had at least 24 months follow-up. Posterior fusion mass bone density was evaluated by measuring hounsfield unit (HU) on CT in three different regions [upper instrumented vertebra (UIV), lower instrumented vertebra, and osteotomy site], and were compared between patients with and without mechanical complications. RESULTS: A total of 165 patients (63.2 years, 33.5% male) were included. Overall PJK rate was 18.8%, and 35.5% of these underwent PJK revision. There was significantly lower density of posterior fusion mass at the UIV in patients who experienced PJK compared with patients without PJK (431.5HU vs. 537.4HU, P =0.026). Overall RF rate was 34.5% and 61.4% of these underwent revision for RFs. Among 57 patients with RFs, 71.9% had pseudarthrosis. Fusion mass density did not differ between patients with or without RFs. However, in RF patients with pseudarthrosis, there was significantly higher bone mass density near the osteotomy compared with those without pseudarthrosis (515.7HU vs. 354.2HU, P =0.012). There were no differences in radiographic sagittal measures between the patients with and without RF or PJK. CONCLUSIONS: Patients with PJK tend to have less dense posterior fusion mass at the UIV. Fusion mass density does not correlate with RF, but greater bone density near the osteotomy was correlated with accompanying pseudarthrosis in patients with RFs. Assessing density of posterior fusion mass on CT may be helpful in assessing risk for PJK and provide insight as to the causes of RFs.

Clinical study of a new type of telescopic rod for the treatment of congenital pseudarthrosis of the tibia in children.

The purpose of this study was to investigate the initial efficacy of a new telescopic rod in the treatment of congenital pseudarthrosis of tibia (CPT) in children. A new type of telescopic rod for children was designed and its clinical results were evaluated. There were nine cases of CPT on the right and six cases on the left; there were six females and nine males. The average age at operation was 35.5 months. There were 12 cases with neurofibromatosis type 1 and 4 cases with proximal tibial dysplasia. The initial healing of tibial pseudarthrosis, proximal tibial valgus deformity, tibial length, ankle valgus, ankle function, and intramedullary rod displacement were evaluated during follow-up. All 15 cases were followed up for an average of 18.2 months, 14 cases achieved initial healing, with an average healing time of 4.3 months. Ten cases had unequal lengths of the tibia, with an average of 0.9 cm. Proximal tibial valgus occurred in seven cases and ankle valgus occurred in one child. The average range of motion of the ankle joint was 23° and the average plantar flexion was 42°. The average extension of the new telescopic rod was 1.6 cm. The displacement of the telescopic rod occurred in seven cases, there was no epiphyseal plate tethering and re-fracture. The new children's telescopic rod has a reasonable design and can extend with the growth of tibia. There are no complications of epiphyseal plate tethering and re-fracture. It provides a new choice of intramedullary fixation for the treatment of CPT.

The incidence of congenital pseudarthrosis of the clavicle and review of the literature.

The aim of this study was to identify the hitherto unknown incidence of congenital pseudarthrosis of the clavicle (CPC), based on a cohort of continuous livebirths born in our hospital, to review the literature and investigate if there is evidence supporting the published association between left-sided CPC and dextrocardia. From our electronic medical record and radiology databases, we identified all live births and patients with the diagnosis of CPC born from 2000 to 2016. We reviewed the imaging which included one or both clavicles to search for unrecorded CPC cases and reviewed all retrievable CPC publications listed in PubMed and publications quoted within these publications going back to 1910. We identified 87 407 livebirths of which 41 800 had radiological studies done, 14 885 showing one or both clavicles. We found five cases of CPC, two from the electronic database and three from our imaging review, giving an incidence of 1 of 17 481 livebirths. We identified 138 publications reporting paediatric and adult CPC cases and 12 review articles, including 429 patients (187 female; 159 male; 83 unknown) with 456 CPCs and a minimum of 24 additional patients from case reports for which we could not retrieve details. Two publications reported one case of left-sided CPC with dextrocardia, either not showing left/right marking or only showing the CPC with the aortic knob on the same side. We report the first CPC incidence of 0.0057%, provide the by far most inclusive CPC epidemiology based on 429 patients and could not find reliable proof that there has ever been a patient with left-sided CPC which was associated with dextrocardia.

Risk Factors for Allograft Subsidence Following Anterior Cervical Discectomy and Fusion.

OBJECTIVE: The purpose this study was to precisely characterize patterns of allograft subsidence following anterior cervical discectomy and fusion (ACDF) utilizing computed tomography scans, determine risk factors for cervical allograft subsidence, and investigate the impact of subsidence on pseudarthrosis rates. METHODS: We performed a retrospective review of patients undergoing 1-to 3-level ACDF utilizing allograft interbodies with anterior plating between 2011 and 2019. Subsidence measurements were performed by 2 independent reviewers on computed tomography scans obtained 6 months postoperatively. Subsidence was then classified as mild if subsidence into the inferior and superior endplates were both ≤2 mm, moderate if the worst subsidence into the inferior- or superior endplate was between 2 and 4 mm, or severe if the worst subsidence into the inferior- or superior endplate was ≥4 mm. Multivariate analysis was performed to identify risk factors for the development of subsidence. RESULTS: We identified 98 patients (152 levels) for inclusion. A total of 73 levels demonstrated mild subsidence (≤2 mm), 61 demonstrated moderate subsidence (2-4 mm), and 18 demonstrated severe subsidence (≥4 mm). On multivariate analysis, risk factors for severe subsidence included excessive vertebral endplate resection and lower screw tip to vertebral body height ratio. Severe subsidence was associated with an increased rate of pseudarthrosis (94.1% vs. 13.6%) without an associated increase in reoperation rate. CONCLUSIONS: Following ACDF with allograft interbodies, 50% of interbodies will subside >2 mm and 10% of interbodies will subside >4 mm. Risk factors for severe subsidence should be mitigated to decrease the risk of pseudarthrosis.

Incidence, mechanism, and protective strategies for 2-year pelvic fixation failure after adult spinal deformity surgery with a minimum six-level fusion.

OBJECTIVE: The purpose of this study was to determine the incidence, mechanism, and potential protective strategies for pelvic fixation failure (PFF) within 2 years after adult spinal deformity (ASD) surgery. METHODS: Data for ASD patients (age ≥ 18 years, minimum of six instrumented levels) with pelvic fixation (S2-alar-iliac [S2AI] and/or iliac screws) with a minimum 2-year follow-up were consecutively collected (2015-2019). Patients with prior pelvic fixation were excluded. PFF was defined as any revision to pelvic screws, which may include broken rods across the lumbosacral junction requiring revision to pelvic screws, pseudarthrosis across the lumbosacral junction requiring revision to pelvic screws, a broken or loose pelvic screw, or sacral/iliac fracture. Patient information including demographic data and health history (age, sex, BMI, smoking status, American Society of Anesthesiologists score, osteoporosis), operative (total instrumented levels [TIL], three-column osteotomy [3CO], interbody fusion), screw (iliac, S2AI, length, diameter), rod (diameter, kickstand), rod pattern (number crossing lumbopelvic junction, lowest instrumented vertebra [LIV] of accessory rod[s], lateral connectors, dual-headed screws), and pre- and postradiographic (lumbar lordosis, pelvic incidence, pelvic tilt, major Cobb angle, lumbosacral fractional curve, C7 coronal vertical axis [CVA], T1 pelvic angle, C7 sagittal vertical axis) parameters was collected. All rods across the lumbosacral junction were cobalt-chrome. All iliac and S2AI screws were closed-headed tulips. Both univariate and multivariate analyses were performed to determine risk factors for PFF. RESULTS: Of 253 patients (mean age 58.9 years, mean TIL 13.6, 3CO 15.8%, L5-S1 interbody 74.7%, mean pelvic screw diameter/length 8.6/87 mm), the 2-year failure rate was 4.3% (n = 11). The mechanisms of failure included broken rods across the lumbosacral junction (n = 4), pseudarthrosis across the lumbosacral junction requiring revision to pelvic screws (n = 3), broken pelvic screw (n = 1), loose pelvic screw (n = 1), sacral/iliac fracture (n = 1), and painful/prominent pelvic screw (n = 1). A higher number of rods crossing the lumbopelvic junction (mean 3.8 no failure vs 2.9 failure, p = 0.009) and accessory rod LIV to S2/ilium (no failure 54.2% vs failure 18.2%, p = 0.003) were protective for failure. Multivariate analysis demonstrated that accessory rod LIV to S2/ilium versus S1 (OR 0.2, p = 0.004) and number of rods crossing the lumbar to pelvis (OR 0.15, p = 0.002) were protective, while worse postoperative CVA (OR 1.5, p = 0.028) was an independent risk factor for failure. CONCLUSIONS: The 2-year PFF rate was low relative to what is reported in the literature, despite patients undergoing long fusion constructs for ASD. The number of rods crossing the lumbopelvic junction and accessory rod LIV to S2/ilium relative to S1 alone likely increase construct stiffness. Residual postoperative coronal malalignment should be avoided to reduce PFF.