Aims. Posterior column plating through the single anterior approach reduces the morbidity in acetabular fractures that require stabilization of both the columns. The aim of this study is to assess the effectiveness of posterior column plating through the anterior intrapelvic approach (AIP) in the management of acetabular fractures. Methods. We retrospectively reviewed the data from R G Kar Medical College, Kolkata, India, from June 2018 to April 2023. Overall, there were 34 acetabulum fractures involving both columns managed by medial buttress plating of posterior column. The posterior column of the acetabular fracture was fixed through the AIP approach with buttress plate on medial surface of posterior column. Mean follow-up was 25 months (13 to 58). Accuracy of reduction and effectiveness of this technique were measured by assessing the Merle d’Aubigné score and Matta’s radiological grading at one year and at latest follow-up. Results. Immediate postoperative radiological Matta’s reduction accuracy showed anatomical reduction (0 to 1 mm) in 23 cases (67.6%), satisfactory (2 to 3 mm) in nine (26.4%), and unsatisfactory (> 3 mm) in two (6%). Merle d’Aubigné score at the end of one year was calculated to be excellent in 18 cases (52.9%), good in 11 (32.3%), fair in three (8.8%), and poor in two (5.9%). Matta’s radiological grading at the end of one year was calculated to be excellent in 16 cases (47%), good in nine (26.4%), six in fair (17.6%), and three in poor (8.8%). Merle d’Aubigné score at latest follow-up deteriorated by one point in some cases, but the grading remained the same; Matta’s radiological grading at latest follow-up also remained unchanged. Conclusion. Stabilization of posterior column through AIP by medial surface plate along the sciatic notch gives good stability to posterior column, and at the same time can avoid morbidity of the additional lateral window. Cite this article: Bone Jt Open 2024;5(2):147–153

Aims. For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis. Methods. We reviewed 15 patients over a five-year period (January 2017 to December 2022) who had undergone extra-articular resection of the hip joint due to malignant tumour using a custom-made osteotomy guide and 3D-printed endoprosthesis. Each of the 15 patients had a single lesion, with six originating from the acetabulum side and nine from the proximal femur. All patients had their posterior column preserved according to the surgical plan. Results. Postoperative pathological assessment revealed a negative surgical margin was achieved in all patients. At final follow-up, 13.3% (2/15) died and no recurrence occurred. The overall survival was 81.7% at five years. None of the patients showed any signs of aseptic loosening, and no wound healing issues were observed. In total, 20% (3/15) developed complications, with two cases of early hip dislocation and one case of deep infection. The cumulative incidence of mechanical and non-mechanical failure in this series was 13.7% and 9.3%, respectively, at five years. In this cohort, the mean time to full weightbearing was 5.89 (SD 0.92) weeks and the mean Musculoskeletal Tumor Society score was 24.1 (SD 4.4). Conclusion. For patients with a hip joint tumour who met the inclusion criteria and were deemed suitable for posterior column preservation, a custom-made osteotomy guide combined with 3D-printed endoprosthesis is worth performing when treating patients who require extra-articular resection of the hip joint, as it can achieve adequate margin for local control, maximize bone preservation to maintain pelvic ring integrity, reduce the risk of complications by simplifying the surgical procedure, and allow for more precise reconstruction for better function. Cite this article: Bone Jt Open 2024;5(11):1027–1036

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Numerous studies have examined the biomechanical properties of the vertebral body following PMMA cement augmentation for the treatment of osteoporotic vertebral body fractures. To date there is no published literature reporting the effects of Vertebroplasty on internal intervertebral disc biomechanics which in turn have been shown to reflect loading patterns of the vertebral column. To study effects of PMMA cement augmentation of vertebral body fractures on intervertebral disc biomechanics using stress prolifometry to assess differential anterior and posterior vertebral column loading. Eight cadaveric motion segments were individually loaded on a hydraulically powered materials testing machine under 1.5kN of axial compression. Following fracture induction the lower vertebral body underwent Vertebroplasty. Profiles of the vertically acting compressive stress were obtained by pulling a pressure sensitive transducer along the mid-sagittal diameter of the intervertebral disc. “Stress profile” measurements were obtained before fracture, following fracture, and after vertebro-plasty both in extension and flexion. Stress profiles were integrated over area to calculate the compressive force across the disc. The compressive load acting on the neural arch was calculated by subtracting the disc force from the applied 1.5kN load. In flexed postures posterior column loading increased from 17.1% to 42.2% following fracture (p< 0.01) and then decreased significantly from 42.2% to 23.68% following vertebroplasty (p< 0.03). There was no significant difference between pre-fracture and post-vertebroplasty status (p=0.11). In extended posture, fracture produced increased posterior column loading 72.9% vs 51.8% (p< 0.005) and following vertebroplasty there was no significant change (p=0.2). In moderate degrees of flexion, vertebroplasty produces normalisation of load bearing through the anterior vertebral column and hence offloads the posterior elements to a significant degree. This could be postulated, to partly account for the analgesic effect seen following vertebroplasty in the clinical setting

Operative approaches to the acetabulum are generally classified into anterior, posterior, extensile or combined approaches. The choice of approach depends upon the fracture pattern and the amount of relative displacement affecting the anterior and posterior bony structures. Occasionally, extensile or combined surgical approaches are indicated for the treatment of complex fracture patterns with extensive involvement of both the anterior and posterior acetabular anatomy. However, it is believed that these approaches may be associated with higher complication rates than more limited surgical approaches. The ilioinguinal approach described by Letournel is routinely employed in the treatment of anterior column, anterior wall, anterior column/posterior hemi- transverse and certain associated both-columns, transverse and T-type fractures. The utility of this approach is sometimes limited by difficulty in visualising, reducing and applying instrumentation to the quadrilateral plate and posterior column components of these fractures. A surgical approach described by Stoppa in 1989—and later extended to acetabular indications by Cole and Bolhofner—can be used, often in combination with the lateral window of the standard ilioinguinal approach, to effectively treat the same range of fractures as an ilioinguinal approach. Access to the quadrilateral plate and certain displaced posterior column fracture lines is enhanced by this approach—possibly eliminating the need for combined or extensile approaches in certain cases. A retrospective study undertaken at our institution demonstrated that anatomic articular reduction was achieved in 14 of 17 complex acetabular fractures treated via a Stoppa approach. All fractures in the study had at least 5 mm of posterior column displacement preoperatively

We describe a 15-year-old boy with a posterior dislocation of the hip, fracture of the posterior column of the acetabulum and separation of the femoral capital epiphysis. To our knowledge no previous case in a child has been reported. Such high-energy injuries are extremely rare, and a poor outcome is expected. We advocate early referral to a specialised tertiary centre, and the use of a modification of Delbet’s classification to reflect the complexity and displacement which may occur with this injury

Purpose of the study. Percutanous acetabular surgery is a new and developing technique in fixation of acetabulum fractures. The most common screw used is the anterior column screw that traverses anterograde or retrograde through the anterior column of the acetabulum. Standard height and width calculations derived from CT scans do not take the trajectory of the screw into consideration. They have been shown to exaggerate the available safe bone corridor for screw passage. Posterior column screws can be placed in a retrograde fashion via the ischial tuberosity to fixate posterior column. Limited international data is available and no studies to date have been conducted on the South African population. This study assesses the anterior and posterior acetabular columns of South African individuals and ascertains the safe bone corridor sizes. Methods. Pelvic CT-scans of 100 randomly selected patients were reviewed. Specific computer software was used to virtually place anterior screws through the anterior acetabular column, in its clinical trajectory. Specific entry points inferior to the pubic tubercles significantly changed the relation of the screw trajectory to the mid- column isthmus and were incorporated in the measurement of the anterior column. All the available lengths and diameters were measured and averages were calculated for males and females. Results. On average, males have longer and larger diameter anterior columns. The entry point on the pubic tubercle has a significant impact on the relative diameter at the mid- column. Not all commercially available cannulated screw diameters are safe to place into the anterior column. Conclusion. Although the international literature shows that percutaneous anterior column fixation is of value for early mobilisation after fractures, intimate knowledge of the local data regarding the available safe corridors for screw passage is limited. This study shows the safe bone corridors that can be used to avoid breaching the cortex during screw insertion. It also recommends safe screw diameters. NO DISCLOSURES

Aims. The aims of this study were to characterize the incidence and risk factors associated with stress fractures following periacetabular osteotomy, and to determine their effect on osteotomy union. Methods. We retrospectively reviewed all periacetabular osteotomies (PAOs) performed for developmental dysplasia of the hip (DDH) at one institution over a six-year period between 2012 and 2017. Perioperative factors were recorded, and included demographic and surgical data. Postoperatively, patients were followed for a minimum of one year with anteroposterior and false profile radiographs of the pelvis to monitor for evidence of stress fracture and union of osteotomies. We characterized the incidence and locations of stress fractures, and used univariate and multivariable analysis to identify factors predictive of stress fracture and the association of stress fracture on osteotomy union. Results. A total of 331 patients underwent PAO during the study period with 56 (15.4%) stress fractures: 46 fractures of the retroacetabular posterior column, five cases of ischiopubic stress fracture, and five cases of concurrent ischiopubic and retroacetabular stress fractures. Overall, 86% (48/56) healed without intervention. Univariate analysis revealed that stress fractures occurred more frequently in females (p = 0.040), older patients (mean age 27.6 years (SD 8.4) vs 23.8 (SD 9.0); p = 0.003), and most often with the use of the broad Mast chisel (28.5%; p < 0.001). Multivariable analysis revealed that increasing age (odds ratio (OR) 1.04; 95% CI 1.01 to 1.07; p = 0.028) and use of the broad Mast chisel (OR 5.1 (95% CI 1.3 to 19.0) compared to narrow Ganz chisel; p = 0.038) and surgeon (p = 0.043) were associated with increased risk of stress fracture. Patients with stress fractures were less likely to have healed osteotomies after one-year follow-up (76% vs 96%; p < 0.001). Conclusion. Stress fracture of the posterior column may be an under-recognized complication following PAO, and the rate may be influenced by surgical technique. Consideration should be given to using a narrow chisel during the ischial cut to reduce the risk of stress propagation through the posterior column. Cite this article: Bone Joint J 2022;104-B(9):1017–1024

The Paprosky acetabular bone defect classification system and related algorithms for acetabular reconstruction cannot properly guide cementless acetabular reconstruction in the presence of porous metal augments. We aimed to introduce a rim, points, and column (RPC)-oriented cementless acetabular reconstruction algorithm and its clinical and radiographic outcomes. A total of 123 patients (128 hips) were enrolled. A minimum 5-year radiographic follow-up was available for 96 (75.8%) hips. The mean clinical and radiographic follow-up durations were 6.8±0.9 (range: 5.2–9.2) and 6.3±1.9 (range: 5.0–9.2) years, respectively. Harris hip score (HHS) improved significantly from 35.39±9.91 preoperatively to 85.98±12.81 postoperatively (P<0.001). Among the fixation modes, 42 (32.8%) hips were reconstructed with rim fixation, 42 (32.8%) with three-point fixation without point reconstruction, 40 (31.3%) with three-point fixation combined with point reconstruction, and 4 (3.1%) with three-point fixation combined with pelvic distraction. Complementary medial wall reconstruction was performed in 20 (15.6%) patients. All acetabular components were radiographically stable. Nine-year cumulative Kaplan–Meier survival rates for 123 patients with the endpoint defined as periprosthetic joint infection, any reoperation, and dissatisfaction were 96.91% (confidence interval [CI]: 86.26%, 99.34%), 97.66% (CI: 92.91%, 99.24%), and 96.06% (CI: 86.4%, 98.89%), respectively. Cup stability in cementless acetabular reconstruction depends on rim or three-point fixation. The continuity of the anterior and posterior columns determines whether the points provide adequate stability to the cup. Medial wall reconstruction is an important complementary fixation method for rim or three-point fixation. The patients who underwent cementless acetabular reconstruction guided by the RPC decision-making algorithm demonstrated satisfactory mid-term clinical function, satisfaction levels, radiographic results, and complication rates

Introduction. Bernese periacetabular osteotomy (PAO) repositions the acetabulum to increase femoral head coverage (FHC) in hip dysplasia. Currently, there is a paucity of objective peri-operative metrics to plan for optimal acetabular fragment repositioning. The MSk Lab Hip 3D Planner (MSkL-HP) measures acetabular morphology and simulates PAO cuts to achieve optimal FHC. We evaluated how adjusting location and orientation of cutting planes can alter FHC. Method. MSkL-HP simulated 274 feasible PAOs on four dysplastic hips. Femoroacetabular anatomy was landmarked to simulate cutting planes. Posterior column and ischial cuts were standardised, whilst iliac and pubic cut combinations varied. The slope of the iliac cut was either neutral (aligned to pelvis), exit point 5mm above the entry point (+5), or 5mm below (-5). The slope of the pubic cut was either 90°, 50°, or 70° (medial-to-lateral). Iliac and pubic cuts were simulated 0, 5 and 15mm - distal and medial – to a classic cut. Outcome measures were achieved LCEA, Tönnis, FHC and % bone overlap at the pubic cut. Targets were LCEA >30°, Tönnis angle <10°, and FHC >70% and minimum bone overlap ≥10%. Results. All feasible PAOs resulted in improvement from pre-operative metrics. Personalised cutting planes provided greater benefit than standard planes. Kruskal Wallis tests showed that the iliac cut at 5mm or 15mm resulted in a greater LCEA and lower Tönnis compared to the classic cut (p<0.05). Changing location of the pubic cut, and slope of the iliac and pubic cuts did not significantly affect LCEA and Tönnis in all hips (p<0.05). Cut combinations optimising metrics were associated with a lower % pubic cut overlap. Conclusion. MSkL-HP feasibly and reliably planned personalised PAO, measuring pre-operative and simulated post-operative objective metrics. Patient-specific pubic and iliac cuts enable greater correction whilst maintaining bone overlap. Further simulations on patients with varying morphology may improve standard techniques

Introduction: Reversed prostheses implantation requires screwing of the glenoid component with prefixed angles. This study is to determine anatomical angles of scapula that take part in reversed prostheses implantation. Material and method: Seventy-three 3-dimensional computed tomography of the scapula and 108 scapular dry specimens were analyzed. Mean age of the CT-3D serie was of 52.59 years old (ranging from 16 to 84). There were 46 females and 27 males. The following measures were made on each patient: length of the neck of the inferior glenoid, angle between the glenoid surface and the upper posterior column of the scapula, angle between the major craneo-caudal glenoid axis and the base of the coracoid process and angle between the major craneo-caudal glenoid axis and the upper posterior column of the scapula. Measures were performed in the AP view as well as in the posterior view of the scapula. Results: The length of the neck of the anterior glenoid was classified into two groups named ‘short-neck’ and ‘long-neck’ for both three-dimensional computed tomography and cadaveric scapulas with statistically significant differences between both groups (p< 0,001 for the three-dimensional computed tomography scapulas and p=0,034 for the cadaveric group). The angle between the glenoid surface and the upper posterior column of the scapula was also classified into two different types: type I (52° ranging from 48° to 57°) and type II (64° ranging from 60° to 70°) with statistically significant differences between both groups (p< 0,001 for the three-dimensional computed tomography scapulas and p< 0,001 for the cadaveric group). The angle between the major craneo-caudal glenoid axis and the center of the base of the coracoid process averaged 18,25° (ranging 13° from to 27°). The angle between the major craneo-caudal glenoid axis and the upper posterior column of the scapula averaged 8° (ranging 5° from to 18°). Conclusions:. - scapulas can be classified into two groups regarding the angle between the glenoid surface and the upper posterior column of the scapula with significant differences between them. - two different lengths of the neck of the inferior glenoid body have also been differentiated in the anterior as well as in the posterior faces of the scapula. - the base of the coracoid process is not in line with the posterior column of the scapula. - three-dimensional computed tomography of the scapula constitutes and important tool when planning reversed prostheses implantation

Pelvic discontinuity is defined as a separation of the ilium superiorly from the ischiopubic segment inferiorly. In 2018, the main management options include the following: 1) hemispheric acetabular component with posterior column plating, 2) cup-cage construct, 3) pelvic distraction, and 4) custom triflange construct. A hemispheric acetabular component with posterior column plating is a good option for acute pelvic discontinuities. However, healing potential is dependent on host's biology and characteristic of the discontinuity. The plate should include 3 screws above and 3 screws below the discontinuity with compression in between. In addition, the hemispherical acetabular component should have at least 50% host bone contact with 3–4 screws superior and 2–3 screws inferior to the discontinuity. On the other hand, a cup-cage construct can be used in any pelvic discontinuity. This includes a highly porous acetabular component placed on remaining host bone. Occasionally, highly porous metal augments are used to fill the remaining bone defects. A supplemental cage is placed over the acetabular component, spanning the discontinuity from the ilium to the ischium. A polyethylene liner is then cemented into place with antibiotic-loaded bone cement. Rarely, pelvic distraction may be needed. With this technique, pelvic stability is obtained via distraction of the discontinuity by elastic recoil of the pelvis and by fixing the superior hemipelvis and inferior hemipelvis to a highly porous metal cup or augment with screws, thereby unitizing the superior and inferior aspects of the pelvis. In essence, the cup acts as a segmental replacement of the acetabulum, with healing occurring to the cup or augment, resulting in a unitised hemipelvis. Frequently, the discontinuity itself does not achieve bony healing. Finally, custom triflange constructs are being utilised with increasing frequency. Triflange cups are custom-designed, porous and/or hydroxyapatite coated, titanium acetabular components with iliac, ischial, and pubic flanges. Rigid fixation promotes healing of the discontinuity and biologic fixation of the implant. It requires a CT scan, dedicated preoperative design, and fabrication costs

Complex spinal deformities can cause pain, neurological symptoms and imbalance (sagittal and/or coronal), severely impairing patients’ quality of life and causing disability. Their treatment has always represented a tough challenge: prior to the introduction of modern internal fixation systems, the only option was an arthrodesis to prevent worsening of the deformity. Then, the introduction of pedicle screws allowed the surgeons to perform powerful corrective manoeuvres, distributing forces over multiple levels, to which eventually associate osteotomies. In treating flexible coronal deformities, in-ternal fixation and corrective manoeuvres may be sufficient: the combination of high density pedicle screws and direct vertebral rotation revolutionized surgical treatment of scoliosis. However, spinal osteotomies are needed for correcting complex rigid deformities; the type of osteot-omy must be chosen according to the aetiology, type and apex of the deformity. When dealing with large radius deformities, spread over multiple levels and without fusion, multiple posterior column os-teotomies such as Smith-Petersen and Ponte (asymmetric, when treating scoliosis) can be performed, dissipating the correction over many levels. Conversely, the management of a sharp, angulated de-formity that involves a few vertebral levels and/or with bony fusion, requires more aggressive 3 col-umn osteotomies such as Pedicle Subtraction Osteotomies (PSO), Bone Disc Bone Osteotomies (BDBO) or Vertebral Column Resection (VCR). Sometimes the deformity is so severe that cannot be corrected with only one osteotomy: in this scenario, multilevel osteotomies can be performed

Using the Mayo Clinic definition (>62mm in women and >66mm in men), the “jumbo acetabular component” is the most successful method for acetabular revisions now, even in hips with severe bone loss. There are numerous advantages: surface contact is maximised; weight-bearing is distributed over a large area of the pelvis; the need for bone grafting is reduced; and usually, hip center of rotation is restored. The possible disadvantages of jumbo cups include: may not restore bone stock; may ream away posterior column or wall; screw fixation required; the possibility of limited bone ingrowth and late failure; and a high rate of dislocation due to acetabular size:femoral head ratio. The techniques for a successful jumbo revision acetabular component involve: sizing-“reaming” of the acetabulum, careful impaction to achieve a “press-fit”, and multiple screw fixation. We recommend placement of an ischial screw in addition to dome and posterior column screw fixation. Cancellous allograft is used for any cavitary defects. The contra-indications for a jumbo acetabular cup are: pelvic dissociation; inability to get a rim fit; and inability to get screw fixation. If stability cannot be achieved with the jumbo cup alone, then use of augment(s), bulk allograft, or cup-cage construct should be considered. Using titanium fiber-metal mesh components, we reported the 15-year survival of 129 revisions. There was 3% revision for deep infection and only 3% revision for aseptic loosening. There were 13 reoperations for other reasons: wear, lysis, dislocation, femoral loosening, and femoral fracture fixation. The survival was 97.3% at 10 years, but it dropped to 82.8% at 15 years. Late loosening of this fiber metal mesh component is likely related to polyethylene wear and loss of fixation. Dislocation is the most common complication of jumbo acetabular revisions, approximately 10%, and these are multifactorial in etiology and often require revision. Based on our experience, we now recommend use of an acetabular component with an enhanced porous coating (tantalum), highly crosslinked polyethylene, and large femoral heads or dual mobility for all jumbo revisions

We undertook a comparative study of magnetic resonance imaging (MRI) vertebral morphometry of thoracic vertebrae of girls with adolescent idiopathic thoracic scoliosis (AIS) and age and gender-matched normal subjects, in order to investigate abnormal differential growth of the anterior and posterior elements of the thoracic vertebrae in patients with scoliosis. Previous studies have suggested that disproportionate growth of the anterior and posterior columns may contribute to the development of AIS. Whole spine MRI was undertaken on 83 girls with AIS between the age of 12 and 14 years, and Cobb’s angles of between 20° and 90°, and 22 age-matched controls. Multiple measurements of each thoracic vertebra were obtained from the best sagittal and axial MRI cuts. Compared with the controls, the scoliotic spines had longer vertebral bodies between T1 and T12 in the anterior column and shorter pedicles with a larger interpedicular distance in the posterior column. The differential growth between the anterior and the posterior elements of each thoracic vertebra in the patients with AIS was significantly different from that in the controls (p < 0.01). There was also a significant positive correlation between the scoliosis severity score and the ratio of differential growth between the anterior and posterior columns for each thoracic vertebra (p < 0.01). Compared with age-matched controls, the longitudinal growth of the vertebral bodies in patients with AIS is disproportionate and faster and mainly occurs by endochondral ossification. In contrast, the circumferential growth by membranous ossification is slower in both the vertebral bodies and pedicles

Modern oncologic treatments have resulted in an increase of the duration of life of patients with cancer; however the onset of a vertebral metastasis results in a decrease of the quality of life. The aim of surgery is to increase or restore the quality, but not the duration of life. The decision for surgery depends mainly on the functional impairment, and more incidentally on the primitive tumor, the metastatic diffusion, and the general status of the patient. Decision for operative technique depends on the anatomical patterns of the metastasis, considered with reference to the three columns classification of Denis. The anterior column initial involvement results in instability with mechanical pain, increased by standing and coughing, decreased by supine position, similar to pain experienced with traumatic instability. The middle column involvement results in foraminal extension with radicular pain. The initial posterior column involvement is unfrequent and diagnosis is usually late as standard X-Rays are negative. At a later stage, invasion of both anterior and middle column result in vertebral collapse with severe mechanical pain and cord compression. This is best treated by anterior approach, allowing a better tumoral resection and a better vertebral reconstruction using bone cement than by posterior approach. Middle and posterior column invasion result in canal invasion and cord compression, without vertebral collapse. Posterior column involvement requires a posterior approach, giving an easy access from C1 down to S1. In selected cases, a combined approach should be recommended because allowing a more complete resection, with less local recurrence rate. Lastly diffuse lesions or multisegmental instability may require a posterior approach and an extensive stabilisation

This report reviews the long-term results of treating acetabula with unusually severe problems, such as pelvic discontinuity or major column loss after failed total hip arthroplasty (THA) and reconstruction problems. Loss of acetabular bone stock results from removal of bone during the original procedure, prosthetic failure, and osteolysis. In massive structural failure, the acetabular rim, quadrilateral plate, and associated columns become deficient. At worst, this may be combined with pelvic discontinuity and disruption of the ilium and ischium. Prosthetic protrusio may result from fixation loss and be associated with scarring of the femoral vessels, femoral nerve, ureter and bowel. A variety of implants has been used to in ace-tabular reconstruction. The results are often poor because of insufficient bone stock to support the implant. In a consecutive series of 251 THA revisions done between 1988 and 1996, 17 patients were treated for major pelvic column loss, pelvic discontinuity or both. In five patients, a posterolateral approach without trochanteric osteotomy was used. The extensile triradiate approach with ilioinguinal extension was used in 12 patients in whom severe prosthetic protrusio increased the risk of intrapelvic iatrogenic injury. A long anterior column pelvic plate was applied. A posteriorly placed AO 4.5-mm pelvic reconstruction plate with 10 to 12 holes was used in nine cases of pelvic discontinuity and in five cases of posterior column bone loss. This plate extended from the most inferior extent of the ischium across the wall of the posterior column to a point high on the ilium. Anterior column fixation was done in eight of nine cases of pelvic discontinuity and all three cases of anterior column deficiency. This called for an 8 to 12-hole 3.5-mm AO pelvic reconstruction plate that extended from the pubic symphysis across the pelvic rim. This spanned the anterior column defect, ranging from 4 cm to 8 cm, to the medial wall of the ilium. Bulk allograft was used in 16 of the 17 patients. The patient in whom allograft was not used had pelvic discontinuity following pelvic irradiation. Whole pelvic acetabular transplants were used in seven with severe bone loss or following resection for chondrosarcoma and the other for pigmented or villonodular synovitis. Posterior segmental acetabular allograft was used in two cases of posterior column absence. Femoral heads were used in two posterior column defects, three pelvic discontinuities with anterior column defect, and two anterior column defects. Acetabular components were cemented in six of seven whole bulk ace-tabular transplants, six of nine pelvic discontinuities and two anterior column defects. Cemented implants were classified as loose if there was a complete radiolucent line at the bone cement interface, measurable component migration or measurable change in position. Uncemented acetabular components were considered loose if component migration had occurred or screws had broken. Pelvic plates were considered loose if there was measurable migration or change in plate position or if fixation screws had backed out or broken. Radiographic union was considered present when bridging callus or trabecular bone was visible across the discontinuity site. Junctional healing was considered probable when radiographs did not show obvious signs of failure. Grafts were considered unhealed if there was obvious displacement, bone gaps or hardware breakage. Seven of the nine patients with pelvic discontinuity had late evidence of healing of the fracture and allograft consolidation. One underwent removal of the graft at three weeks after developing acute postoperative infection: early junctional healing of a whole bulk acetabular allograft required an osteotomy to break up the interface. Another patient, who underwent removal of the graft and implant at three months for chronic infection, had consolidation of a whole bulk ace-tabular allograft. One patient underwent revision of a pressfitted acetabular component at 60 months, and the pelvic discontinuity was solidly united. In a fourth patient, explored at 124 months for loosening of a cemented cup, there was near complete dissolution of the graft posterior acetabular wall and a loose posterior pelvic plate. In a patient with pelvic discontinuity after radiation therapy for uterine carcinoma, satisfactory healing of the pelvic discontinuity was confirmed at 32 months, when excisional arthroplasty for late chronic infection followed urinary sepsis. Seven patients had major column loss with severe cavitary defects. Consolidation of the allograft was noted in all seven within the first 12 months of follow-up. Revision (47%) was required for infection in three patients, implant loosening in four, and recurrent implant dislocation in one. The four loose cups were revised to a cemented all-polyethylene component. All four implants had been placed on less than 50% host bone. None of the four has required subsequent revision. Dislocation postoperatively occurred in eight patients. In six, the extensile triradiate approach had been used. This approach led to dislocation in 50%. The main reasons for using the extensile triradiate approach were to avoid catastrophic injuries by direct exposure of vital structures and to allow stable anterior column plate fixation. In that no neurovascular injuries occurred and stable durable allograft consolidation and healing of pelvic discontinuity took place, these goals were largely met. Three patients developed late sciatic palsy. In one, plaster immobilisation had possibly caused direct pressure over the fibular head and led to chronic peroneal palsy. The other two underwent additional exploration of the sciatic nerve for late entrapment caused by migration of screws from the posterior column plate. Two patients developed bladder infections postoperatively. Another developed superficial phlebitis of the lower leg. Acetabular revision for loosening was necessary in three of seven cementless implants, while only two of 10 cemented implants failed. The acetabular component should be cemented into the allograft when more than 50% of the prosthetic interface is non-viable. Virtually all graft material, including dense cortical grafts, may ultimately fail if used for implant fixation. Patients should be told about the inevitable risks. However, techniques used led to stable healing of the pelvic discontinuity in most cases. Long pelvic plates that securely stabilise the pelvis and allografts carefully opposed to host bone may explain the relative success in this series

The use of intramedullary column screws in the treatment of acetabular fractures is becoming more widely utilized. The development of percutaneous methods to insert these screws under image intensifier guidance is one of the main reasons for their increased use. Few groups are navigating insertion of these screws. The available screws are cannulated 6.5–8 mm screws. Most surgeons prefer using 3.2 mm guide wires to reduce deflection. With a shank diameter of 4.5 mm, 3.2 mm cannulation significantly weakens the screws. We postulated that both columns, specially the posterior column can accommodate larger screw diameters which will increase the stability of fixation allowing earlier full weight bearing. The currently used screws were designed for fixation of femoral neck fractures. As percutaneous fixation of acetabular fractures is a growing area of interest, this warrants designing suitable screws with larger diameters. Eight CT scans of the adult pelvis –performed for non fracture related indications-, were studied (7 females, 1 male). We found that the anatomical cross-section of the columns is irregular but approximately triangular. The method we used to determine the largest diameter of a screw to fit each column was fitting cylinders in the columns. Robin’s 3D software was used to segment acetabula and convert the CT data into polygon mesh (stereolithography STL format) bone surfaces at an appropriate Hounsfield value. The resulting STL files were imported in Robin’s Cloud software, where polygon mesh cylinders of 10 mm diameter were fitted in each column. These cylinders were then manipulated to achieve best fit and their diameters were gradually increased to the biggest diameter which still fitted in the column. The mean diameters of the fitted cylinders were 10.8 mm (range: 10–13mm) and 15.2 mm (range 14–16.5mm) for the anterior and posterior columns respectively. To our knowledge, this is the first investigation to study the cross sectional dimensions of the anterior and posterior columns of the acetabulum. Our small sample shows that both columns can safely accommodate larger screws than those currently used. We plan to investigate this further using cadavers

Aims. Severe acetabular bone loss and pelvic discontinuity (PD) present particular challenges in revision total hip arthroplasty. To deal with such complex situations, cup-cage reconstruction has emerged as an option for treating this situation. We aimed to examine our success in using this technique for these anatomical problems. Patients and Methods. We undertook a retrospective, single-centre series of 35 hips in 34 patients (seven male, 27 female) treated with a cup-cage construct using a trabecular metal shell in conjunction with a titanium cage, for severe acetabular bone loss between 2011 and 2015. The mean age at the time of surgery was 70 years (42 to 85) and all patients had an acetabular defect graded as Paprosky Type 2C through to 3B, with 24 hips (69%) having PD. The mean follow-up was 47 months (25 to 84). Results. The cumulative five-year survivorship of the implant with revision for any cause was 89% (95% confidence interval (CI) 72 to 96) with eight hips at risk. No revision was required for aseptic loosening; however, one patient with one hip (3%) required removal of the ischial flange of the cage due to sciatic nerve irritation. Two patients (6%; two hips) suffered from hip dislocation, whereas one patient (one hip) required revision surgery with cement fixation of a dual-mobility acetababular component into a well-fixed cup-cage construct. Two patients (6%; two hips) developed periprosthetic infection. One patient was successfully controlled with a two-stage revision surgery, while the other patient underwent excision arthroplasty due to severe medical comorbidities. For the whole series, the Harris Hip Score significantly improved from a mean of 30 (15 to 51) preoperatively to 71 (40 to 89) at the latest follow-up (p < 0.001). Conclusion. Our findings suggest that cup-cage reconstruction is a viable option for major segmental bone defects involving the posterior column and PD. It allows adequate restoration of the acetabulum centre with generally good stability and satisfactory postoperative function. Instability and infection remain drawbacks in these challenging revision cases. Cite this article: Bone Joint J 2018;100-B:1442–48

Introduction and Aims: Traditional treatment for adolescent hyperkyphosis, including Scheuermann’s disease, has included apical anterior spine release/fusion (ASF) prior to posterior instrumented fusion. We wished to reassess the need for ASF when using a posterior column shortening technique with a threaded rod compression instrumentation system. Method: PSF-only group: 17 patients, mean age 15.7 years (range 12.8–18.5), underwent posterior column shortening by chevron-shaped lamina resection and fusion using hybrid hook/screw, dual 4.8mm threaded compression rod instrumentation (TRI). A/PSF group: seven patients, mean age 15.4 years (14–16.8), underwent open or endoscopic ASF followed by posterior TRI. Fourteen of 24 patients had strict Sorensen criteria of Scheuermann’s. At mean follow-up of 30 months (range 24–56), patients were assessed for amount and maintenance of correction, sagittal balance, and evidence of pseudoarthrosis. Results: Mean pre-operative measured kyphosis in PSF-only was 79.6 degrees (range 67–90), and was corrected to 38.2 degrees (22–55) post-operative, and 37.1 degrees (22–50, 53%) at final follow-up. In the A/PSF group, pre-operative kyphosis was 79.0 degrees (62–93), corrected to 41.6 degrees (34–48) post-operative, and was 42.6 degrees (25–48, 46%) at final follow-up. There was no difference in the amount of correction (p=.28) or its maintenance between the two groups. Similarly, there were no differences between groups in assessing pre-operative and final T2-12 kyphosis (p=.13), T12-S1 lordosis (p=.98), or C7 sagittal balance (p=.10). The mean T10-L2 sagittal alignment was improved in the PSF-only patients (final kyphosis 7.8°) vs. 18.9° in the A/PSF patients (p=.04). There was a greater correction of Voutsinas’ index (PSF-only=.08, A/PSF=.15, p=.01) for the posterior-only group. No patient lost > eight degrees correction (range 12–8) between immediate post-operative and final follow-up, and no instrumentation complications occurred. Conclusion: Using posterior column shortening and larger diameter (4.8mm) threaded rods with hooks cephalad to the apex and screws caudal, we have found no advantage in correction from preliminary anterior apical release, nor a difference in maintenance of correction. ASF is unnecessary when adolescent hyperkyphosis/Scheuermann’s is treated by this technique