Step-cut osteotomy of the anterior superior iliac spine for increased visualisation in the Levine approach for Bernese periacetabular osteotomy surgery.

BACKGROUND: Hip dysplasia can lead to pain and dysfunction in the young adult. Acetabular undercoverage leads to abnormal joint loading and results in joint degeneration, accelerating need for arthroplasty in this patient population. Conceptually, treatment focuses on increasing acetabular coverage in the form of periacetabular osteotomy. The procedure can be performed through the iliofemoral approach, and performing an anterior superior iliac spine (ASIS) osteotomy can enhance the visualisation in this approach. Several techniques have been described for ASIS osteotomy. AIM: The purpose this study was to report on step-cut technique for ASIS osteotomy during the Bernese periacetabular osteotomy procedure to enhance visualisation when utilising the iliofemoral approach. SURGICAL TECHNIQUE: This step-cut technique enhances stability at the osteotomy site, and minimises soft tissue dissection to reduce pain and assists with maintaining a stable fixation construct postoperatively. RESULTS: There were no nonunions and minimal morbidity to the lateral femoral cutaneous nerve injury in cohort of 86 patients while utilising this technique. CONCLUSIONS: We recommend using this step-cut ostetomy of the ASIS during Bernese periactetabular osteotomy for benefit of increasing exposure while maintaining a low complication profile.

Defining Posterior Wall Fragments in Associated Both Column Acetabular Fractures (OTA/AO 62C).

OBJECTIVE: Associated both column acetabular fractures (OTA/AO 62C) with concomitant posterior wall fracture fragments (ABC + PW) have not been well-defined. The purpose of this study was to report on the incidence and morphology of ABC + PW fractures. METHODS: A retrospective review of associated both column (ABC) fractures between 2014 and 2020 was performed. Computed tomography scans including 3-D surface rendered reformats for each were reviewed to determine whether a posterior wall (PW) fragment was present and its morphologic characteristics. RESULTS: One hundred fifty-two ABC fractures were identified. Sixty-two fractures (41%) were identified as ABC + PW. 3D-computed tomographies were available on 58 fractures. Morphologic analysis was performed based on the relationship of the fracture to the gluteal pillar. Twenty PW fragments were posterior to the gluteal pillar, 19 extended into the gluteal pillar, and 19 extended anterior. Fifty-two fractures were treated with operative fixation; 32 (62%) were clamped and fixed with screws from the same anterior approach whereas 15 (29%) required a separate posterior approach; and no fixation was placed in 5 (9%). 29 of 32 PW fragments (91%) requiring fixation that extended into or anterior to the pillar were fixed from the anterior approach, and 7 of 15 posterior fractures (47%) required a separate posterior approach. CONCLUSIONS: A separate PW fragment was identified in 41% of ABC fractures. Their variation in morphology can be classified into 3 types based on the relation to the gluteal pillar that has potential implications for treatment from the anterior approach compared with requiring a separate posterior approach. We suggest these data could be used to update the 2018 OTA/AO Fracture Compendium. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Osteology of the ilium revised: illuminating the clinical relevance.

BACKGROUND: Several studies on anterior and posterior pelvic ring fixation have identified a fragile monocortical area located at the iliac wing. However, there are no current studies regarding this structure's dimensions and relation to known anatomic structures. METHODS: Eleven human ilia were dissected from 6 specimens. After debulking soft tissue, photoluminescence was used to indicate the fragile area. The size and thickness of the iliac wing were determined and mapped in relation to the anterior superior iliac spine (ASIS) and the posterior superior iliac spine (PSIS). RESULTS: This photoluminescent unicortical area measured 15.57 cm2 with a mean minimal thickness of 1.37 mm at its thinnest part. Its average diameter was 41.15 mm horizontally and 37.45 mm vertically. In all cases, it was located at the middle third of the ilium with a mean distance of 64.58 mm to the AIIS and 62.73 mm to the PSIS. Trajectory angulation above 4.5° from the PSIS lead to violation of this area. CONCLUSION: This study provides useful anatomical information regarding a thin unicortical area at the iliac wing that is relevant to anterior and posterior pelvic ring fixation and the potential complications that can arise from iatrogenic perforation of this area.

Asymmetry of the pelvic ring evaluated by CT-based 3D statistical modeling.

The human pelvis is a complex anatomical structure that consists of the innominate bones, sacrum and coccyx to form the pelvic ring. Even though considered to be a symmetric entity, asymmetry of the pelvic ring (APR) might occur to alter its anatomy, function, or biomechanics or to impact assessment and treatment of clinical cases. APR and its assessment is complicated by the intricate anatomy of the pelvic ring. There is only limited information and understanding about APR with no established evaluation methods existing. The objective of the present study was to adopt CT-based 3D statistical modeling and analysis to assess APR within the complex anatomy of the pelvic ring. We were interested to establish a better understanding of APR with knowledge and applications transferred to human anatomy, related research, and development subjects and to clinical settings. A series of 150 routine, clinical, pelvic CT protocols of European and Asian males and females (64 ± 15 (20-90) years old) were post-processed to compute gender- and ancestry-specific 3D statistical models of the pelvic ring. Evaluations comprised principal component analysis (PCA) that included size, shape, and asymmetry patterns and their variations to be assessed. Four different CT-based 3D statistical models of the entire pelvic ring were computed according to the gender and ancestry specific groups. PCA mainly displayed size and shape variations. Examination of additional PCA modes permitted six distinct asymmetry patterns to be identified. They were located at the sacrum, iliac crest, pelvic brim, pubic symphysis, inferior pubic ramus, and near to the acetabulum. Accordingly, the pelvic ring demonstrated not to be entirely symmetric. Assessment of its asymmetry proved to be a challenging task. Using CT-based 3D statistical modeling and PCA, we identified six distinct APRs that were located at different anatomical regions. These regions are more prone to APRs than other sites. Minor asymmetry patterns have to be distinguished from the distinct APRs. Side differences with regard to size, shape, and/or position require to be taken into account. APRs may be due different load mechanisms applied via spine or lower extremity or locally. There is a need for simpler and efficient, yet reliable methods to be routinely transferred to human anatomy, related research, and development subjects and to clinical settings.

The impact of the 30 most cited articles on hip arthroscopy: what is the subject matter?

The purpose of this study was to identify the 30 most cited articles on hip arthroscopy and discuss their influence on recent surgical treatment. Due to advancements in hip arthroscopy, there is a widening spectrum of diagnostic and treatment indications. The purpose of this study was to identify the 30 most cited articles on hip arthroscopy and discuss their influence on contemporary surgical treatment. The Thomson Reuters Web of Science was used to identify the 30 most cited studies on hip arthroscopy between 1900 and 2018. These 30 articles generated 6152 citations with an average of 205.07 citations per item. Number of citations ranged from 146 to 461. Twenty-five out of the 30 papers were clinical cohort studies with a level of evidence between III and IV, encompassing 4348 patients. Four studies were reviewed (one including a technical note) and one a case report. We were able to identify the 30 most cited articles in the field of hip arthroscopy. Most articles were reported in high-impact journals, but reported small sample sizes in a retrospective setting. Prospective multi-arm cohort trials or randomized clinical trials represent opportunities for future studies.

The Ilioinguinal Surgical Approach Using a Modified Medial Window: Origin, Evolution, and Applications. A 34-Year Perspective.

Emile Letournel's ilioinguinal approach provided unprecedented surgical access to the anterior aspect of the innominate bone. A refinement of this approach is described which incorporates a modified medial window that limits dissection around the external iliac vessels, expands surgical exposure of the anterior pelvic ring, and provides additional reduction possibilities while preserving the capabilities of the lateral and middle windows.

Generic Preoperative Planning for Proximal Femoral Osteotomy in the Treatment of Nonunion of the Femoral Neck.

Despite improvements in surgical technique and overall patient care, failed treatment of fractures of the femoral neck persists. For the physiologically young patient, joint preservation is the preferred method of treatment. Unfortunately, the best treatment option, proximal femoral osteotomy, is fast becoming a lost art. Preoperative planning is critical in this regard. The described preoperative planning work flow is a reliable method for obtaining the desired deformity correction for a variety of proximal femoral malunions and nonunion. Revisiting the classic Pauwels osteotomy for femoral neck nonunion is an appropriate vehicle to supply the first link in resurrecting this treatment modality by providing a standardized preoperative planning protocol.

Plate fixation in periprosthetic femur fractures Vancouver type B1-Trochanteric hook plate or subtrochanterical bicortical locking?

INTRODUCTION: Proximal plate fixation in periprosthetic femur fractures can be improved by plate anchorage in the greater trochanter (lateral tension band principle) or bicortical locking screw placement beside the prosthesis stem in an embracement configuration. Both concepts were compared in a biomechanical test using a femoral hook plate (hook) or a locking attachment plate (LAP). METHODS: After bone mineral density (BMD) measurement in the greater trochanter, six pairs of fresh frozen human femora were assigned to two groups and instrumented with cemented hip endoprostheses. A transverse osteotomy was set distal to the tip of the prosthesis, simulating a Vancouver B1 fracture. Each pair was instrumented using a plate tensioner with either hook or LAP construct. Cyclic testing (2Hz) with physiologic profile and monotonically increasing load was performed until catastrophic failure. Plate stiffness was compared in a four-point-bending-test. Paired student's-t-test was used for statistical evaluation (p<0.05). RESULTS: Mean BMD was 250mgHA/ccm±47. The hook construct exhibited a significantly (p=0.015) lower number of cycles and load to failure (26'177cycles±2777; 3'118N±778) correlating significantly with BMD (R2=0.83; p=0.04) compared to the LAP construct (37'423cycles±5'299; 4'242N±1'030) (R2=0.71;p=0.11). BMD was a significant covariate (p=0.01). Plate stiffness was in a comparable range (hook Plate 468N/mm±7; LCP 445N/mm±6). CONCLUSION: Subtrochanterically placed LAP provides an increased fixation strength under repetitive loading compared to hook plate fixation in the greater trochanter. Trochanteric fixation is highly BMD dependent and may be restricted to major greater trochanteric involvement requiring stabilization.

Surgical exposure and fixation of displaced type IV, V, and VI glenoid fractures.

Displaced intra-articular fractures of the glenoid are rare and frequently result from high-energy injuries. Types IV, V, and VI fractures have in common a fracture line which extends medially into the scapular body. These fracture patterns present unique challenges for surgical approaches and reduction and fixation strategies. A modified posterior approach allows for the simultaneous exposure of the medial scapular border and the glenoid articular surface. An initial reduction of the medial fracture indirectly restores the scapular relationship, allowing for subsequent completion of the articular reduction via a limited approach to the posterior shoulder using the same incision.

Multisegmental open sacral fracture due to impalement: a case report.

We report on an unusual impalement injury to the sacrum in a 15-year-old adolescent patient. This open pelvic fracture resulted in a shattered sacrum with neurologic impairment including clinically absent anal sphincter tone and perineal sensation. Early debridement, wound revision, neural decompression, fracture reduction, and stable fixation using lumbopelvic fixation according to the principles of triangular osteosynthesis resulted in a favorable outcome with primary wound healing, return of bowel and bladder control, as well as immediate patient mobilization.

Nonunion treatment: iliac crest bone graft techniques.

In the management of nonunions, detailed surgical treatment plans will vary depending on the underlying etiology of the specific case. Iliac crest autogenous bone grafting, although associated with donor site complications, continues to be a necessary part of the treatment of many nonunions. This article summarizes the classification of nonunions and the use of iliac crest autogenous bone grafting, the standard against which any new technique must be measured.

Sacroiliac joint pain.

The sacroiliac joint is a source of pain in the lower back and buttocks in approximately 15% of the population. Diagnosing sacroiliac joint-mediated pain is difficult because the presenting complaints are similar to those of other causes of back pain. Patients with sacroiliac joint-mediated pain rarely report pain above L5; most localize their pain to the area around the posterior superior iliac spine. Radiographic and laboratory tests primarily help exclude other sources of low back pain. Magnetic resonance imaging, computed tomography, and bone scans of the sacroiliac joint cannot reliably determine whether the joint is the source of the pain. Controlled analgesic injections of the sacroiliac joint are the most important tool in the diagnosis. Treatment modalities include medications, physical therapy, bracing, manual therapy, injections, radiofrequency denervation, and arthrodesis; however, no published prospective data compare the efficacy of these modalities.

Nonunion of femoral neck fracture and trochanteric osteotomy after a pinned, slipped capital femoral epiphysis: a case report.

Femoral neck fracture as a complication of slipped capital femoral epiphysis (SCFE) is rare. Even rarer is a femoral neck nonunion as an additional complication. This is the first case reported in the literature of a failed valgus osteotomy for a femoral neck nonunion. A salvage operation involving a step-cut valgus/flexion/internal rotation osteotomy, open reduction and internal fixation, with a blade plate and cannulated screw, placement of an allograft femoral strut, and allograft bone grafting was successfully performed. Femoral neck fractures following SCFE fixation are more difficult to treat because of abnormal femoral neck configuration. Therefore a valgus, flexion, and internal rotation producing osteotomy may need to be initially performed to prevent a femoral neck nonunion.

Antiviral inhibition of the HIV-1 capsid protein.

During the assembly stage of the human immunodeficiency virus (HIV) replication cycle, several thousand copies of the viral Gag polyprotein associate at the cell membrane and bud to form an immature, non-infectious virion. Gag is subsequently cleaved by the protease, which liberates the capsid proteins for assembly into the polyprotein shell of the central core particle (or capsid) of the mature virus. Viral infectivity is critically dependent on capsid formation and stability, making the capsid protein a potentially attractive antiviral target. We have identified compounds that bind to an apical site on the N-terminal domain of the HIV-1 capsid protein and inhibit capsid assembly in vitro. One compound, N-(3-chloro-4-methylphenyl)-N'-[2-[([5-[(dimethylamino)-methyl]-2-furyl]-methyl)-sulfanyl]ethyl]urea) (CAP-1), is well tolerated in cell cultures, enabling in vivo antiviral and mechanistic studies. CAP-1 inhibits HIV-1 infectivity in a dose-dependent manner, but does not interfere with viral entry, reverse transcription, integration, proteolytic processing, or virus production, indicating a novel antiviral mechanism. Significantly, virus particles generated in the presence of CAP-1 exhibit heterogeneous sizes and abnormal core morphologies, consistent with inhibited CA-CA interactions during virus assembly and maturation. These findings lay the groundwork for the development of assembly inhibitors as a new class of therapeutic agents for the treatment of AIDS.

Retrovirus capsid protein assembly arrangements.

During retrovirus particle assembly and morphogenesis, the retrovirus structural (Gag) proteins organize into two different arrangements: an immature form assembled by precursor Gag (PrGag) proteins; and a mature form, composed of proteins processed from PrGag. Central to both Gag protein arrangements is the capsid (CA) protein, a domain of PrGag, which is cleaved from the precursor to yield a mature Gag protein composed of an N-terminal domain (NTD), a flexible linker region, and a C-terminal domain (CTD). Because Gag interactions have proven difficult to examine in virions, a number of investigations have focused on the analysis of structures assembled in vitro. We have used electron microscope (EM) image reconstruction techniques to examine assembly products formed by two different CA variants of both human immunodeficiency virus type 1 (HIV-1) and the Moloney murine leukemia virus (M-MuLV). Interestingly, two types of hexameric protein arrangements were observed for each virus type. One organizational scheme featured hexamers composed of putative NTD dimer subunits, with sharing of subunits between neighbor hexamers. The second arrangement used apparent NTD monomers to coordinate hexamers, involved no subunit sharing, and employed putative CTD interactions to connect hexamers. Conversion between the two assembly forms may be achieved by making or breaking the proposed symmetric NTD dimer contacts in a process that appears to mimic viral morphogenesis.

Hexagonal organization of Moloney murine leukemia virus capsid proteins.

To help elucidate the mechanisms by which retrovirus structural proteins associate to form virus particles, we have examined membrane-bound assemblies of Moloney murine leukemia virus (M-MuLV) capsid (CA) proteins. Electron microscopy and image reconstruction techniques showed that CA dimers appear to function as organizational subunits of the cage-like, membrane-bound protein arrays. However, new three-dimensional (3D) data also were consistent with hexagonal (p6) assembly models. The p6 3D reconstructions of membrane-bound M-MuLV CA proteins gave unit cells of a = b = 80.3 A, c = 110 A, gamma = 120 degrees, in which six dimer units formed a cage lattice. Neighbor cage hole-to-hole distances were 45 A, while distances between hexagonal cage holes corresponded to unit cell lengths (80.3 A). The hexagonal model predicts two types of cage holes (trimer and hexamer holes), uses symmetric head-to-head dimer building blocks, and permits the introduction of lattice curvature by conversion of hexamer to pentamer units. The M-MuLV CA lattice is similar to those formed in helical tubes by HIV CA in that hexamer units surround cage holes of 25-30 A, but differs in that M-MuLV hexamer units appear to be CA dimers, whereas HIV CA units appear to be monomers. These results suggest that while general assembly principles apply to different retroviruses, clear assembly distinctions exist between these virus types.

Analysis of Rous sarcoma virus capsid protein variants assembled on lipid monolayers.

During assembly and morphogenesis of Rous sarcoma virus (RSV), proteolytic processing of the structural precursor (Pr76Gag) protein generates three capsid (CA) protein variants, CA476, CA479, and CA488. The proteins share identical N-terminal domains (NTDs), but are truncated at residues corresponding to gag codons 476, 479, and 488 in their CA C-terminal domains (CTDs). To characterize oligomeric forms of the RSV CA variants, we examined 2D crystals of the capsid proteins, assembled on lipid monolayers. Using electron microscopy and image analysis approaches, the CA proteins were observed to organize in hexagonal (p6) arrangements, where rings of membrane-proximal NTD hexamers were spaced at 95 A intervals. Differences between the oligomeric structures of the CA variants were most evident in membrane-distal regions, where apparent CTDs interconnect hexamer rings. In this region, CA488 connections were observed readily, while CA476 and CA479 contacts were resolved poorly, suggesting that in vivo processing of CA488 to the shorter forms may permit virions to adopt a dissembly-competent conformation. In addition to crystalline arrays, the CA479 and CA488 proteins formed small spherical particles with diameters of 165-175 A. The spheres appear to be arranged from hexamer or hexamer plus pentamer ring subunits that are related to the 2D crystal forms. Our results implicate RSV CA hexamer rings as basic elements in the assembly of RSV virus cores.