Additional Screw Research Articles

Additional Reduction Screw Fixation Technique for Pertrochanteric Hip Fractures: A Novel Method to Prevent Excessive Sliding in Cephalomedullary Nail Surgery

Extramedullary (EM) reduction, defined as the medial cortex of the head-neck fragment located outside the medullary canal of the distal shaft fragment, has been introduced to prevent excessive postoperative sliding or failure of the lag screw in pertrochanteric fracture surgeries. Favorable EM reduction results have recently been reported in several clinical and biomechanical studies. Despite these efforts, maintaining the head-neck fragment in an EM position is periodically a difficult and challenging problem. Herein, the technique for reduction and maintenance of the head-neck fragment was introduced in an EM position using a Kirschner wire and partially threaded cannulated screw fixation via screw fixation from EM to the head-neck fragment, which was positioned inferior to the lag screw on the femoral calcar, also called the reduction screw. The authors utilized this reduction screw in 34 pertrochanteric fracture surgeries using a cephalomedullary nail and fracture union was acheive in all cases by a minimum one-year follow-up period without surgical complications.

Scapular spine base fracture with long outside-in superior or posterior screws with reverse shoulder arthroplasty.

BackgroundThe purpose of the present study was to determine how long superior screws alone or in combination with posterior placement of metaglene screws protruding and penetrating into the scapular spine in reverse total shoulder arthroplasty affect the strength of the scapular spine in a fresh cadaveric scapular model.MethodsSeven fresh cadaver scapulas were allocated to the control group (short posterior and superior screws) and seven scapulars to the study group (spine base fixation with a four long screws, three with both long superior and long posterior screws).ResultsThe failure load was lower in the spine fixation group (long screw, 869 N vs. short screw, 1,123 N); however, this difference did not reach statistical significance (p>0.05). All outside-in long superior or superior plus posterior screws failed due to scapular spine base fracture; failures in the short screw group were due to acromion fracture. An additional posterior outside-in screw failed to significantly decrease the failure load of the acromion spine.ConclusionsThe present study highlights the significance of preventing a cortical breach or an outside-in configuration when a superior or posterior screw is inserted into the scapular spine base.

Characterization and rate of symptomatic adjacent-segment disease after index lateral lumbar interbody fusion: a single-institution, multisurgeon case series with long-term follow-up.

The rate of symptomatic adjacent-segment disease (ASD) after newer minimally invasive techniques, such as lateral lumbar interbody fusion (LLIF), is not known. This study aimed to assess the incidence of surgically significant ASD in adult patients who have undergone index LLIF and to identify any predictive factors. Patients who underwent index LLIF with or without additional posterior pedicle screw fixation between 2010 and 2012 and received a minimum of 2 years of postoperative follow-up were retrospectively included. Demographic and perioperative data were recorded, as well as radiographic data and immediate perioperative complications. The primary endpoint was revision surgery at the level above or below the previous construct, from which a survivorship model of patients with surgically significant symptomatic ASD was created. Sixty-seven patients with a total of 163 interbody levels were included in this analysis. In total, 17 (25.4%) patients developed surgically significant ASD and required additional surgery, with a mean ± SD time to revision of 3.59 ± 2.55 years. The mean annual rate of surgically significant ASD was 3.49% over 7.27 years, which was the average follow-up. One-third of patients developed significant disease within 2 years of index surgery, and 1 patient required surgery at the adjacent level within 1 year. Constructs spanning 3 or fewer interbody levels were significantly associated with increased risk of surgically significant ASD; however, instrument termination at the thoracolumbar junction did not increase this risk. Surgically significant ASD was not impacted by preoperative disc height, foraminal area at the adjacent levels, or changes in global or segmental lumbar lordosis. The risk of surgically significant ASD after LLIF was similar to the previously reported rates of other minimally invasive spine procedures. Patients with shorter constructs had higher rates of subsequent ASD.

Comparison of Fixation Techniques in Oblique and Biplanar Chevron Medial Malleolar Osteotomies; a Finite Element Analysis

This study aimed to evaluate different fixation techniques and implants in oblique and biplanar chevron medial malleolar osteotomies using finite element analysis. Both oblique and biplanar chevron osteotomy models were created, and each osteotomy was fixed with 2 different screws (3.5 mm cortical screw and 4.0 mm malleolar screw) in 2 different configurations; (1) 2 perpendicular screws, and (2) an additional third transverse screw. Nine simulation scenarios were set up, including 8 osteotomy fixations and the intact ankle. A bodyweight of 810.44 N vertical loading was applied to simulate a single leg stand on a fixed ankle. Sliding, separation, frictional stress, contact pressures between the fragments were analyzed. Maximum sliding (58.347µm) was seen in oblique osteotomy fixed with 2 malleolar screws, and the minimum sliding (17.272 µm) was seen in chevron osteotomy fixed with 3 cortical screws. The maximum separation was seen in chevron osteotomy fixed with 2 malleolar screws, and the minimum separation was seen in oblique osteotomy fixed with 3 cortical screws. Maximum contact pressure and the frictional stress at the osteotomy plane were obtained in chevron osteotomy fixed with 3 cortical screws. The closest value to normal tibiotalar contact pressures was obtained in chevron osteotomy fixed with 3 cortical screws. This study revealed that cortical screws provided better stability compared to malleolar screws in each tested osteotomy and fixation configuration. The insertion of the third transverse screw decreased both sliding and separation. Biplanar chevron osteotomy fixed with 3 cortical screws was the most stable model.

Treatment of a coronal shear injury of the trochlea using a modified hedgehog-based technique through an anterior neurovascular interval approach: A case report.

Introduction and importanceSurgical treatment for dislocated trochlear shear injuries is recommended due to its articular nature. However, the surgical exposure is often limited and large cartilaginous fragments with lack of subchondral bone stock makes a stable fixation technically challenging. Rapid swelling of the traumatized cartilage induces a size misfit between the cartilage of the fragment and the defect site. The use of a “modified hedgehog”-based technique might be a solution in these cases. However, this technique has only been described in chondral shear lesions of the knee.Case presentationA fifteen-year-old boy fell out of the still rings during gymnastics at school and suffered trauma to his elbow. A CT-scan of the right elbow showed a coronal shear injury of the trochlea with accompanied lateral condyle fracture of the humerus. The patient was treated throughout an anterior neurovascular approach with a modified hedgehog-based technique with triple fixation by creating an interlocking match of the cartilage, application of fibrin glue and additional screw fixation.Clinical discussionThe anterior neurovascular interval approach provides a clear exposure of the fracture site which is useful for anatomic reduction and triple fixation. The subsequent modified hedgehog-based technique has only been described once in children with shear-off chondral fragments of the knee, without additional screw fixation. Adding a screw fixation of the fragment creates some collateral damage to the cartilage and might not be necessary in future cases.ConclusionThe anterior neurovascular approach seems elegant and provides adequate exposure. Furthermore, a modified hedgehog-based technique delivers a stable triple fixation of the osteochondral fragment.

RADIOGRAPHIC FOLLOW-UP AFTER MILD SLIPPED CAPITAL FEMORAL EPIPHYSIS: WHAT IS THE INCIDENCE OF SUBSEQUENT SURGERY FOR FEMORACETABULAR IMPINGEMENT?

Background:Slipped capital femoral epiphysis (SCFE) is characterized by translation of the proximal femoral epiphysis posterior and medial relative to the metaphysis. The gold standard treatment of mild SCFE, defined as a slip angle <30°, remains in-situ pinning (ISP) to stabilize the epiphysis in its current position after slippage.Methods:127 hips from 113 individuals met inclusion criteria: mild SCFE (Southwick angle <30°) that underwent ISP with available pre- and post-procedure radiographs. Medical records were reviewed to collect demographic data, preoperative symptoms, surgical details, radiographic measurements, and post-operative follow-up. Six hips were identified as having undergone additional joint preserving surgery of the hip (JPSH) while seven other hips were identified as having undergone screw removal and/or replacement within two years of initial ISP. Anterior-posterior (AP) and frog-leg lateral alpha angles, femoral epiphyseal-metaphyseal offset angle, and Southwick angle were all measured preoperatively, post-operatively, and at final radiographic follow-up. Chi-squared analyses, binary logistic regression models and Kruskal-Wallis tests were used to evaluate the association between clinical and radiographic parameters and the occurrence of additional surgery or screw failure.Results:Demographic variables, including age, body mass index, prodrome pain, sex, laterality, and chronicity were not found to significantly influence the likelihood of additional surgery. Preoperative AP alpha angle, frog-lateral alpha angle, epiphyseal-metaphyseal offset angle, and Southwick angle did not significantly impact the likelihood of additional surgery or screw failure. Radiographic measurements taken after ISP demonstrated that AP alpha angle significantly increased the likelihood of additional surgery. For every one degree increase, the likelihood of additional surgery increased 1.091 times (average 70.264° for no additional surgery and 82.333° for additional surgery, p=0.017).Conclusion:Mild SCFE can progress to residual pain and limited hip motion even after initial treatment with ISP. Of our cohort of 127 hips, six (4.72%) went on to have secondary JPSH while an additional seven (5.51%) presented with screw failure within two years of initial ISP. Increased AP alpha angle after ISP was correlated with an increased likelihood of secondary JPSH. This increased AP alpha angle may contribute to intra-articular pathology due to CAM-type morphology which may lead to the necessity of JPSH. These findings suggest that patients with increased AP alpha angle after ISP may need to be followed long-term for the development of further joint symptoms and may need to be counseled after ISP for mild SCFE for the risk of secondary JPSH.Tables/Figures:

A prospective study of outcome in management of neglected fracture neck of femur by internal fixation and tensor fascia lata muscle pedicle graft

Background: Fractures of the neck of the femur have always presented great challenges to Orthopaedic Surgeons and remain in many ways today the unsolved fracture as far as treatment and results are concerned. Methods: Early anatomical reduction, compression of the fracture, and rigid internal fixation are used to promote union, but the surgeon probably has less control over osteonecrosis as the blood supply to the femoral head after femoral neck fracture is quite precarious. Many different devices have been devised for internal fixation of femoral neck fractures, but currently two are commonly used. They are multiple cannulated screws and Dynamic Hip Screw with an additional anti-rotation screw. We studied 14 cases of 1 month-to-one year old fracture neck of femur. All of them had viable head of femur. There was varying degree of resorption of neck of femur, One patient had pathological fracture neck of femur but head of femur was viable. 12 cases were treated with closed reduction, internal fixation with cannulated cancellous screws, augmented with Tensor fascia lata (TFL) muscle pedicle graft to the neck of femur .2 cases were treated with closed reduction, internal fixation with Dynamic hip screw, augmented with TFL Muscle pedicle graft to the neck of femur. Results: 12 cases showed union of fracture, 2 cases were lost in follow up, all 12 patients were able to return to routine daily activities, and one case had avascular necrosis (AVN) with poor function of hip. Conclusion: Fracture neck of femur new or old when treated with stable reduction, alignment as per Garden's index, rigid internal fixation with augmentation by Tensor fascia muscle pedicle grafting for re-establishment of vascularity to head of the femur resulted in 100% union.

Dynamic trial fitting of the cup in press-fit total hip arthroplasty, a feasibility study

Trial fitting of the cup during total hip arthroplasty (THA) is done by trial cups, which do not resemble the real press-fit obtained by the definitive implant. Our goal is to judge feasibility of the X-pander® in clinical practice ; a device developed to mimic the real press-fit obtained by the definitive cup, to ensure satisfactory press-fit. In this feasibility study 45 experienced orthopaedic surgeons from 7 European countries filled in a structured survey after 78 primary THA and 31 revision surgeries, using the X-pander instead of traditional trial cups. Primary outcomes were decision change concerning cup size or further reaming and increased confidence regarding cup insertion and size. Additionally, potential association between the primary outcomes and procedure (primary or revi- sion), bone quality and experience of the surgeon were evaluated. In 33.3% of the primary and 32.2% of the revision cases the X-pander measurement changed the deci- sion and further reaming or change of cup size was decided. In 61.5% and 58.1% of respectively the primary and revision THAs the X-pander was judged to give fairly to much more reliable information than traditional trial cups. The X-pander could lead to less additional screw fixation, as stated in 37.2% of the primary and 25.8% of the revision cases and to better cup insertion in respectively 50.0% and 51.6%. This study validates that the X-pander may be a suitable option for accurate sizing and assessment of the reamed acetabulum and could replace traditional trial cups in THA.

A Comparison of Drill Guiding and Screw Guiding 3D-Printing Techniques for Intra- and Extrapedicular Screw Insertion.

Screw randomized cadaveric study. To compare the accuracy of three-dimensional (3D)-printed drill guides versus additional screw guiding techniques for challenging intra- and extrapedicular screw trajectories. Pedicle screw placement can be technically demanding, especially in syndromic scoliosis with limited bone stock. Recently, 3D-printing and virtual planning technology have become available as new tools to improve pedicle screw insertion. Differences in techniques exist, while some focus on guiding the drill, others also actively guide subsequent screws insertion. The accuracy of various 3D-printing-assisted techniques has been studied; however, direct comparative studies have yet to determine whether there is a benefit of additional screw guidance. Two cadaveric experiments were conducted to compare drill guides with two techniques that introduce additional screw guiding. The screw guiding consisted of either k-wire cannulated screws or modular guides, which were designed to guide the screw in addition to the drill bit. Screws were inserted intra- or extrapedicular using one of each methods according to a randomization scheme. Postoperative computed tomography scanning was performed and fused with the preoperative planning for detailed 3D screw deviation analysis. For intrapedicular screw trajectories malpositioning was low (2%) and the modular guides revealed a statistically significant increase of accuracy (P = 0.05) compared with drill guides. All techniques showed accurate cervical screw insertion without breach. For the extrapedicular screw trajectories both additional screw guiding methods did not significantly (P = 0.09) improve accuracy and malpositioning rates remained high (24%). In this cadaveric study it was found that the additional screw-guiding techniques are not superior to the regular 3D-printed drill guides for the technically demanding extrapedicular screw technique. For intrapedicular screw insertion, modular guides can improve insertion; however, at cervical levels regular 3D-printed drill guides already demonstrated very high accuracy and therefore there is no benefit from additional screw guiding techniques. 3.

Double plating - surgical technique and good clinical results in complex and highly unstable proximal humeral fractures

IntroductionA stable fixation of highly unstable proximal humerus fractures remains challenging and complication rates, especially secondary varus dislocation, remains high. Different techniques of double plate osteosynthesis have been suggested for the treatment of complex proximal humeral fractures as they are well established for other fractures. The aim of this study was to evaluate an operative technique using an angular stable lateral plate supported by a one-third tubular plate positioned anteriorly at the lesser tuberosity for unstable proximal humeral fractures. Patients and methodsRetrospectively, patients treated with a double plate osteosynthesis were included between January 2014 and December 2017. Out of 31, 25 patients (80.6%) with an average age of 53.1 years ± 12.5 were available for follow-up. 60% of the patients were male. The clinical evaluation consisted of a physical examination and standardised questionnaire including subjective and objective shoulder scores like the Constant-Murley Shoulder Score, Simple Shoulder Score, and Subjective Shoulder Value. ResultsAfter a mean follow-up of 30.9 months (range, 12-76 months) eighteen patients (72%) had either excellent or good results regarding the Constant-Murley Shoulder Score with a mean value of 77 points ± 17. Average Simple Shoulder Score was 76% ± 0.2 and Subjective Shoulder Value 72% ± 0.2%. Mean NSA at time of follow-up 135° ± 13°. Nine patients had an implant-removal, five in combination with arthrolysis after a mean of 7.2 months. Three patients underwent surgery for secondary arthroplasty. The study shows a complication rate of 16%. No revision-surgery because of secondary varus dislocation was reported. DiscussionArthroplasty is the less favourable treatment for a younger, active cohort of patients with highly unstable proximal humeral fractures as results are not as good and options for revision are limited. Double plate osteosynthesis can be used in addition to calcar screws, bone graft augmentation, cement augmentation and additional free screws for more multidirectional stability and shows good clinical results despite a higher rate of avascular necrosis and high primary stability with comparable complication-rates to single plate osteosynthesis. It seems to be a valid alternative to primary fracture arthroplasty and can prevent secondary varus displacement.

Comparative Safety of the TFN-ADVANCED Proximal Femoral Nailing System: Findings from a U.S. Health-Care Database.

Proximal femoral fractures are often treated with cephalomedullary nails. Although nail breakages following fracture repair are infrequent, a recent implant retrieval study suggested that the TFN-ADVANCED (TFNA) Proximal Femoral Nailing System (DePuy Synthes) was susceptible to post-implant breakage. It is unclear whether the risk of breakage among patients who receive the TFNA implant is higher than patients who receive other comparable cephalomedullary nails. The current study was designed to evaluate the comparative risk of breakage of the TFNA nail. Using data from a large U.S. health-care database, the current study was designed to determine whether TFNA nails have equal, lower, or higher risk of breakage relative to all other comparable, single-head-element (with no additional lag screws), cephalomedullary nails, the Stryker Gamma3 and the Zimmer Natural Nail, referred to in this study as the non-TFNA group. Data were from patients who received the TFNA implant or non-TFNA nails in 365 hospitals between February 1, 2014, and September 30, 2019. Analysis of nail breakage post-implantation was prespecified as the difference between the TFNA group and the non-TFNA group in cumulative incidence at 18 months, with a prespecified equivalence margin of 0.5%, using data balanced on measured covariates by propensity score weighting. Within the first 18 months of implantation, in 14,370 patients with TFNA nails, there were 27 nail breakages, and in 8,260 patients with non-TFNA nails, there were 29 nail breakages. The mean time to nail breakage was 4.72 months for the TFNA group and 4.05 months for the non-TFNA group. In the balanced data, the risk of breakage at 18 months was 0.26% (95% confidence interval [CI], 0.17% to 0.36%) for the TFNA group and 0.25% (95% CI, 0.05% to 0.45%) for the non-TFNA group, with a risk difference of 0.01% (95% CI, -0.21% to 0.24%). This result indicates that the cumulative incidence of nail breakage was equivalent (between -0.5% and 0.5%) for both nail groups. The risk differences were also within the equivalence margin in subgroup analyses: pertrochanteric fractures only (-0.08% [95% CI, -0.34% to 0.19%]), pertrochanteric or subtrochanteric fractures (-0.04% [95% CI, -0.29% to 0.21%]), and those with International Classification of Diseases, Tenth Revision (ICD-10) data only (0.03% [95% CI, -0.18% to 0.25%]). The risk of nail breakage was equivalent for TFNA and comparator cephalomedullary nails. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The forgotten fragment: additional lesser tuberosity fixation of 4-part proximal humeral fractures-a biomechanical investigation.

Fractures of the proximal humerus are common. The most frequent surgical treatment option is open reduction and locking plate fixation. Multifragmentary fractures, including 3- and 4-part fractures, are especially challenging to treat because they correlate with an increased risk of fixation failure. In the past, several mechanisms of additional fixation were investigated, but none directly addressed the lesser tuberosity (LT). The goal of this study was to investigate the biomechanical impact of additional anterior fracture fixation in lateral locked plating (LLP) of 4-part proximal humeral fractures (PHFs). Twenty-seven fresh frozen human shoulder specimens (mean age, 80 years) with intact rotator cuffs (RCs) were randomized into 4 groups: 3-part PHF with LLP and RC cerclage (n = 6); 4-part PHF with LLP and RC cerclage as standard of care (n = 7); 4-part PHF with LLP, RC cerclage, and 2 anterior 3.5-mm cortical screws (n = 7); and 4-part PHF with LLP, RC cerclage, and additional anterior one-third tubular plate (additional anterior plating [AAP], n = 7). Static load of the RC was simulated with weights. A force-controlled cyclic loading test was performed with a servo-hydraulic testing machine, followed by load-to-failure testing. An optical motion capture system recorded humeral head range of motion. LLP of a 4-part PHF showed more humeral head motion than LLP of a 3-part PHF without fracture of the LT (P < .001). Fixing the LT to the humeral head with two 3.5-mm screws significantly reduced humeral head motion compared with LLP with RC cerclage alone (P < .006). Using AAP significantly increased the construct stiffness compared with the standard of care (P = .03). LLP of a 4-part PHF is biomechanically less stable than LLP of a 3-part PHF without fracture of the LT. Additional screw fixation of the LT in 4-part PHFs improves stability compared with LLP alone. In case of metaphyseal comminution, AAP is favorable from a biomechanical perspective.

Short Term Results of Fixation of Unstable Thoracolumbar Fractures with and without Intermediate Screws: A Comparative Study

Background: Posterior short-segment pedicle screw fixation is widely used for unstable thoracolumbar (TL) fractures. Adding a pedicle screw at the fractured vertebrae could significantly improve the stability and decrease the stress on fixation construct. Objective: Compare the efficacy of short segment pedicle screw fixation with and without intermediate screw in correction of the vertebral body height, local kyphosis and maintenance of the correction in the treatment of unstable thoracolumbar spine fractures. Patients and Methods: This study was a prospective cohort study. 40 patients with unstable thoracolumbar fracture were divided randomly into 2 groups according to the surgical method used. In group B, 20 patients underwent fixation via short-segment pedicle screw instrumentation (1 level above and 1 level below the fractured level). In group A, 20 patients received additional screws at the fractured vertebrae. Results: Both groups had significant correction in Cobb angle, anterior body height and local kyphotic angle. However group A had significantly higher correction achieved in Cobb angle (10.35 ± 6.02), anterior body height (1.15 ± 0.50) and local kyphotic angle (13.30 ± 7.54) than group B (3.45 ± 3.94), (0.40 ± 0.41) and (5.05 ± 4.36) respectively. Nevertheless, the differences in VAS score (p=0.759) and ODI (p=0.934) were not significant. Moreover, group A had a significantly lower loss of correction in Cobb angle (p=0.025) after twelve months of follow up. Conclusion: The construct with intermediate screw was associated with not only better correction but also less correction loss after 12 months. However, this was not reflected on clinical outcome.

Finite element analysis of different locking plate fixation methods for the treatment of ulnar head fracture

BackgroundUlnar head fractures are increasingly higher with the growing proportion of the elderly people. Failure to achieve a stable anatomic reduction of ulna head fracture may lead to a distal radioulnar joint (DRUJ) dysfunction and nonunion of the distal radius. Due to the lack of the postoperative reporting outcomes and the biomechanical studies, it has not been well established about the optimal management of the comminuted distal ulna head fracture. Hence, the purpose of this study is to use finite element analysis to explain the advantages and disadvantages of ulnar-side locking plate fixation compared with dorsal-side locking plate fixation and its screw arrangement in the treatment of ulnar head fractures.MethodsFE models of the ulnar head fracture and the models of ulnar-side locking plate and dorsal-side plate with two or three distal screws was constructed. In order to simulate forces acting on the ulnar and the osteosynthesis material during daily-life activity in subjects who underwent reconstructive surgery, we applied three loading conditions to each model, viz. 20 N axial compression, 50 N axial compression, 1 N∙m torsion moment, 1 N∙m lateral bending moments, and 1 N∙m extension bending moments. Under these conditions, values of the von Mises stress (VMS) distribution of the implant, peak VMS, the relative displacement of the head and shaft fragments between the fracture ends and the displacement and its direction of the models were investigated.ResultsThe stress values of ulnar-side plates were lower than those of dorsal-side plates. And the ulnar-plate fixation system also has smaller maximum displacement and relative displacement. When adding a screw in the middle hole of the ulnar head, the values of model displacement and the peak stress in fixation system are lower, but it may evidently concentrate the stress on the middle screw.ConclusionsIn conclusion, our study indicated that ulnar-side locking plates resulted in a lower stress distribution in the plate and better stability than dorsal-side locking plates for ulnar head fracture fixation. Adding an additional screw to the ulnar head could increase the stability of the fixation system and provide an anti-torsion function. This study requires clinical confirmation of its practicality in the treatment of ulnar head fractures. This study requires clinical confirmation as to its practicality in the treatment of ulnar head fracture.

Trabecular Metal Augments for Treatment of Acetabular Defects: A Systematic Review

AbstractSevere acetabular bone defects during revision total hip arthroplasty are often treated with a hemispherical shell and highly porous modular metal augments. Several papers have been already published reporting on the clinical performance of trabecular metal (TM) augments combined with a hemispherical shell for the management of severe acetabular defects. However, no systematic review of the literature has been published to date. The U.S. National Library of Medicine (PubMed/MEDLINE), EMBASE, and the Cochrane Database of Systematic Reviews were queried for publications utilizing keywords pertinent to tantalum augments and TM (Zimmer Biomet, Warsaw, Indiana) augments, revision THA, clinical outcomes, and complications associated with these procedures. Fifteen articles were found to be suitable for inclusion in the present study, which included 769 revision cases where acetabular augments were used. The majority of acetabular bone defects were type 3 according to the Paprosky classification (type 2A in 58 cases, 7.2%; type 2B in 139 cases, 17.2%; type 2C in 72 cases, 8.9%; type 3A in 360 cases, 44.7%; and type 3B in 177 cases, 22.0%). The overall revision rate for the 769 acetabular revisions with augments was 5.7% (46 cases) at mean mid-term follow-up. The most common reasons for revision were dislocation (3.3%), periprosthetic joint infection (2.9%), and aseptic loosening (2.7%). TM augments combined with hemispherical shells were found to be effective in the treatment of moderate-to-severe acetabular bone defects with a 5% acetabular component revision rate at mean mid-term follow-up. The literature did not delineate whether pelvic discontinuity was associated with a higher risk of aseptic loosening after TM augment. Further studies are needed to clarify the impact of additional screw fixation on survival rates, and whether the type of augment (wedge augments, “flying buttress” augments, column augments), the configuration used, and the number of screws influence clinical and radiographic outcomes.

Periprosthetic occult acetabular fracture: an unknown side effect of press-fit techniques in primary cementless total hip arthroplasty.

This study sought to investigate the prevalence and risk factors of periprosthetic occult acetabular fracture occurring during cementless acetabular cup insertion in patients undergoing primary total hip arthroplasty (THA) and to assess the clinical consequences of these fractures. A total of 232 hips (n = 205 patients) were included in this study. A periprosthetic occult acetabular fracture was defined as that which was unrecognised intraoperatively and was undetectable on post-operative radiographs yet was successfully diagnosed on post-operative computed tomography (CT) images. Clinical (age, sex, body mass index, and preoperative diagnosis) and surgical (additional screw fixation, cup rim size, and cup type) variables were analysed to identify risk factors for periprosthetic occult acetabular fracture. Sixteen (6.9%) periprosthetic occult intraoperative acetabular fractures were identified. In addition, one (0.4%) periprosthetic acetabular fracture was found during operation. The superolateral wall (9/16 hips; 56.3%) was the most frequent location. In addition, one (0.4%) periprosthetic acetabular fracture was found during operation. Male sex was the only factor associated with an increased risk for periprosthetic occult intraoperative acetabular fracture (odds ratio for male versus female sex: 4.28; p = 0.04). There was no significant association between cup type and the occurrence of periprosthetic occult acetabular fracture. All 16 hips with periprosthetic occult intraoperative acetabular fracture were healed at the final follow-up visit without the requirement for any additional surgical interventions. The results of the current study suggest that periprosthetic occult acetabular fractures are common during press-fit acetabular cup insertion in primary THA. Surgeons should have a high index of suspicion and early CT imaging referral in male patients who present with unexplained early post-operative groin pain in primary THA using cementless acetabular cups.

Press-fit reverse shoulder arthroplasty in case of advanced humeral bone loss – Is additional distal fixation necessary for primary stability?

BackgroundRevision reverse shoulder arthroplasty (RSA) poses considerable surgical challenges. We hypothesized that a newly developed press-fit stem, which is modeled on the medullary canal of the supracondylar region of the distal humerus by a slight distal bend, achieve both correct fit and sufficient primary stability and that additional distal fixation by interlocking screws is favorable in case of advanced humeral bone loss. MethodsA modular tapered press-fit stem was implanted in 16 Sawbone humeri in three consecutively created defect situations (200 mm (experimental group type 3°), 160 mm (type 4°) and 120 mm (type 5°) bone length above the epicondylar line. In experimental groups type 4° and 5°, additional distal interlocking screw fixation with one to three screws was tested. Primary stability was investigated by measuring micromotions with a high-precision rotational setup. FindingsHighest relative micromotions were noted at the proximal end in experimental groups type 3° and type 4°, whereas in type 5° highest micromotions could be seen at the distal end. Overall micromotions were significantly lower in type 3° and increased with extended defect size. In experimental group type 5°, micromotions increased with reduced additional distal screw fixation. InterpretationThe examined press-fit stem did not provide sufficient primary rotational stability in all constructs without additional support. Advanced distal humeral bone loss had a strong impact on primary fixation. In experimental group type 5° with 120 mm bone remaining, it might be beneficial to use three distal interlocking screws in the supracondylar region in order to neutralize torque and to avoid early loosening.

Early outcomes of THA using uncemented dual-mobility cups with additional fixation screws

Background: The use of fixation screws with uncemented cups is controversial particularly for dual mobility (DM) cups where perforation of the articular surface could compromise implant longevity. We aimed to compare outcomes of total hip arthroplasty (THA) using uncemented DM cups with supplementary screw fixation versus simple press-fit fixation. Methods: From 235 consecutive THAs performed using uncemented DM cups, 203 were fixed by simple press-fit and 32 fixed with additional screws. The Oxford hip score (OHS) and EuroQol 5 Dimensions (EQ-5D) score were available at 3.3±1.1 years. To enable direct comparison, each screw fixation cup was matched to three simple press-fit cups using propensity scores, based on age, sex and bone quality. Results: The two groups had equivalent age, body mass index, gender distribution, femoral morphology and bone quality. Compared to the press-fit group (n=96), the screw fixation group had more surgical antecedents (p=0.032), higher femoral neck angles (p=0.028), and received slightly larger cups (p=0.036). Revision was required for two (6%) screw fixation cups (only one implant-related) and one (1%) press-fit cup (none implant-related). There were no differences between OHS (19±8 vs 18±7, p=0.682) nor EQ-5D (0.63±0.37, p=0.257). Conclusions: Revision rates were greater for DM cups fixed with additional screws than for those fixed by simple press-fit, but clinical scores were equivalent. There was only one implant-related revision (acetabular fracture) in the screw fixation group and it is unclear whether this is related to the additional screws or to patient/surgical factors. Level of evidence: Level IV, retrospective case series.

Is initial interfragmentary compression made to last? An ovine bone in vitro study.

Interfragmentary compression, a major principle of fracture treatment, is clinically not quantified and might be lost quickly even without functional loads. We designed an experimental study hypothesizing that (1) compression can be controlled using either lag screw or compression plate, and expecting similar initial compression, (2) loss of interfragmentary compression through relaxation within one hour is reduced with neutralization locking plate next to lag screw compared to compression plate. Twelve ovine femora (N=6) and humeri (N=6) were assigned into groups: Group 1 received a 45° oblique osteotomy at mid-diaphysis and was fixated using a 3.5mm interfragmentary lag screw and locking compression plate (3.5mm LCP, DePuy Synthes) as neutralization plate. Group 2 received a transverse osteotomy and was fixated with dynamic compression using compression plate (LCP). Interfragmentary pressure and relative bone fragment displacements were recorded over one hour. Median loss of compression over one hour time (relaxation) were 0.52% in Group 1, and 0.17% in Group 2 (p>0.05). Median rotational displacements amounted to 0.46° for Group 1, and 0.31° for Group 2, and axial displacement to a median of -20μm in Group 1 and 25μm in Group 2. Ovine bone interfragmentary stress relaxation maintains compression over the first hour for lag screw with neutralization plate for an oblique fracture line or compression plate for a transverse fracture line. Measured compression forces around 100N could be overcome by physiological tension loading in bending or torsion, necessitating for instance tension band plating, additional lag screws or absolutive stability.

Radiologic results of additional single screw fixation with lateral locking plate after hybrid closed-wedge high tibial osteotomy

BackgroundHybrid closed-wedge high tibial osteotomy (hybrid CWHTO) is an effective surgical treatment for medial compartment osteoarthritis of the knee. Our study investigated whether the combination of a lateral locking plate and a single medial screw promoted bone union after hybrid CWHTO.MethodsThe study cohort consisted of 30 patients (15 men and 15 women) who underwent hybrid CWHTO for medial compartment osteoarthritis or spontaneous osteonecrosis of the knee. Sixteen knees were fixed with a lateral locking plate (LP group), and 17 were fixed with both a lateral locking plate and a cannulated cancellous screw on the medial side of the tibia (LPS group). The times to bone union, radiolucency, and callus formation at the osteotomy site were evaluated radiographically.ResultsThe mean postoperative time to radiographic confirmation of bone union was 5.5 ± 2.6 months in the LP group and 3.4 ± 1.5 months in the LPS group. Radiolucency at the osteotomy site and excess callus formation on the posterior side of the tibia were lower in the LPS group than in the LP group.ConclusionsThis modified hybrid CWHTO combining a lateral locking plate and a cannulated cancellous screw on the medial side of the tibia improves the stability of the osteotomy site and shortens the period of bone union.