Apex Of Head Research Articles

666 Audit of Tip-Apex Distance in Dynamic Hip Screw Fixation of Proximal Femoral Fractures

Abstract Aim Lag screw cutout is the commonest mechanical failure in dynamic hip screw (DHS) fixation of proximal femoral fractures. Tip-apex distance (TAD), the combined distance from the tip of the lag screw to the apex of the femoral head on AP and lateral views, is the most important predictive factor for cutout. TAD >25mm is associated with a high risk of cutout. The aim was to determine the proportion of DHS fixations performed in our department with ‘acceptable’ TAD (<25mm) and assess the impact of weekly departmental metalwork meetings. Method Retrospective data was collected of all DHS fixations performed in our department in a 6-month period. Intraoperative imaging was reviewed to determine TAD. Posters illustrating TAD recommendations were displayed in theatre, and a weekly departmental metalwork meeting was introduced, reviewing imaging from all surgeries performed. Post-intervention, a further audit cycle over a 6-month period was performed. Results 50 patients underwent DHS fixation during the initial audit cycle. Mean TAD was 22.85mm (range 15mm – 36mm); TAD exceeded 25mm in 13 cases (26%). In the second cycle (n=53), mean TAD reduced to 14.95mm (range 8.5mm – 29.4mm), with 1 case exceeding 25mm (2%). Conclusions The introduction of a weekly departmental metalwork meeting has significantly reduced the mean tip-apex distance of DHS fixations in our department, as well as the proportion of fixations with an unacceptable TAD. This should reduce the risk of lag screw cutout in these patients.

What is the Optimal Nail Length to Treat Osteoporotic Subtrochanteric Fractures? A Finite Element Analysis.

Operative management with intramedullary nail fixation remains the definitive treatment of choice for osteoporotic subtrochanteric (ST) fractures; however, there remains no consensus regarding the proper nail length. We aimed to use 3-dimensional finite element (FE) analysis to determine the optimal nail length for the safe fixation of osteoporotic ST fractures. Nine modes of FE models were constructed using 9 different lengths of cephalomedullary nails (short nails: 170, 180, and 200 mm; long nails: 280, 300, 320, 340, 360, and 380 mm) from the same company. The interfragmentary motion was analyzed. Additionally, the peak von Mises stress (PVMS) in the cortical bone, cancellous bone of the femoral head, and the nail were measured, and the yielding risk for each subject was investigated. Long nails were associated with less interfragmentary motion. In the cortical bone, the PVMS of short nails was observed at the distal locking screw holes of the femoral medial cortex; however, in long nails, the PVMS was observed at the lag screw holes on the lateral cortex. The mean yielding risk of long nails was 40.1% lower than that of short nails. For the cancellous bone of the femoral head, the PVMS in all 9 FE models was in the same area: at the apex of the femoral head. There was no difference in the yielding risk between short and long nails. For implants, the PVMS was at the distal locking screw hole of the nail body in the short nails and the nail body at the fracture level in the long nails. The mean yielding risk was 74.9% lower for long nails than that for short nails. Compared to short nails, long nails with a length of 320 mm or more showed less interfragmentary motion and lower yielding risk in low-level osteoporotic ST fractures. The FE analysis supports long nails as a safer option than short nails, especially for treating transverse-type low-level osteoporotic ST fractures.

In vitro biomechanical analysis of a locking self-compression screw model applied to Pauwels III and comminuted femoral neck fractures

Femoral neck fractures (FNFs) affect the young adult population and are intimately related to high-energy trauma. Despite innovations in osteosynthesis materials, the rate of complications remains at 10%–59% in Pauwels type III (PIII) fractures. The authors thus propose a fixation model with a novel self-compression screw, comparing it to a sliding hip screw plate associated with a derotation screw in the fixation of a PIII fracture with posterior inferior comminution. The finite element method (FEM) was used in this comparison along with a virtual femur model with structural characteristics similar to those of a healthy young human bone. We formed 4 groups: Group 1 (GC), intact bone; Group 2 (SHS+S), sliding hip screw plate with derotation screw; Group 3 (XS), X-pin + SS (self-compression model with superior positioning screw); Group 4 (XI), X-pin + IS (self-compression model with inferior positioning screw). A 700 N monotonic load was applied to the apex of the femur head towards the ground so that stress was mainly focused on the fracture site and osteosynthesis. Analyses included total displacement and maximum principal stress and were performed for all groups. Fracture displacement, rotation, and von Mises were assessed only in groups that underwent osteosynthesis. Total displacement values in groups with self-compression screws (XS and XI) were closer to those for healthy femurs, with a 38.5% reduction when comparing the XS group with the SHS+S group. Fracture displacement and rotation values presented reductions of over 60% when comparing the XS and XI groups with the SHS+S group. Equivalent Von Mises stress values were similar between XS and XI and presented a reduction of approximately 5.25% when compared with the SHS+S group. Our FEM analyses demonstrated that the self-compression screw model has potential biomechanical advantages over the SHS+S model.

A new coccid family, Adocimycolidae fam. nov. (Hemiptera: Coccomorpha), with extended hamulohalteres in Burmese (Myanmar) amber

The present paper describes a male coccid (Hemiptera: Coccoidea) in mid-Cretaceous Burmese amber with the largest known hamulohalteres on any extant or extinct coccid. Aside from this character, the specimen has an unusual assortment of features, including a prolonged head with three cylindrical dorsal simple eyes in three rows joining laterally, a single ocellus dorsally placed at apex of a prolonged head, compound eyes in a ventro-lateral position and a 10-segmented antennae longer than body length. These features prohibit it from being assigned to any known extant or extinct family. Whether the large hamulohalteres on Adocimycolus aarondavisii gen. et sp. nov. are evidence of a plesiomorphic state of a lineage of Mesozoic Coccoidea that had fully developed metathoracic wings or could be a genetic mutation, is addressed.

The first fossil Scarites (Coleoptera: Carabidae) from the Duho Formation (middle Miocene), Korean Peninsula

We report Scarites sp. as the first fossil Coleoptera from Duho Formation in Korean Peninsula. It is characterized by rounded margins of pronotum, straight posterior part of compound eyes, overall oval shape from apex of head to thorax, lateral margins of elytra slightly rounded, and thick antenna cleaner on protibia. Until now, most terrestrial fossils with description from Duho Formation are plant fossils and only marine animal fossils were described. This insect is the first terrestrial animal fossil found in the Duho Formation, possibly the first accurate fossil representative of the genus Scarites.

Which parameters are more reliable in proximal humerus surgery in terms of the axillary nerve?

This study aims to examine the reliability of the old and new parameters in determining the axillary nerve safe area for surgical interventions in the proximal humerus by measuring the distances between the top of the humeral head, the top of the greater tuberosity, the base of the greater tuberosity, and the acromion and axillary nerve. Between 2020 and 2022, a total of 52 shoulders of 26 fresh frozen male human cadavers (mean age: 46±25.5 years; range, 28 to 64 years), 26 right and 26 left were included. The deltopectoral approach was used. The intersection distances of the anterolateral end of the acromion, the top of the humeral head, the top of the tuberculum majus, and the base of the tuberculum majus with the N. axillaries were determined. All measurements were performed using the Microscribe® G2X. The mean distance from the top of the tuberculum majus to the axillary nerve (shown as "A") was measured as 4.36±0.17 cm and 4±0.21 cm on the right and left, respectively. The mean distance from the center of the base of the tuberculum majus to the axillary nerve (shown as "B") was measured as 1.27±0.18 cm and 1.24±0.11 cm on the right and left, respectively. The mean distance from the apex of the humeral head to the axillary nerve (shown as "C") was measured as 6.15±0.39 cm and 5.89±0.34 cm on the right and left, respectively. The mean distance between the anterolateral end of the acromion (shown as "D") was measured as 6.15±0.39 cm and 5.89±0.34 cm on the right and left, respectively. There was a moderate positive correlation between distances A and B measured on the right and left side, respectively (r=0.484; p=0.012) (r=0.454; p=0.020). A strong positive correlation was found between the distances A and B. The A, B, and C parameters had a weak correlation with parameter D. The anatomical parameters A and B was found to be less variable and more reliable than parameter D.

Surgical exposure to posterolateral quadrant tibial plateau fractures: an anatomic comparison of posterolateral and posteromedial approaches

BackgroundManagement of posterolateral tibial plateau quadrant fractures can be challenging, and two posterior approaches were frequently used for exposure, reduction, and fixation: posterolateral approach and posteromedial approach. The purpose of this study was to compare their deep anatomical structure and analyze their limits and the risk of injury to important structures during surgical dissection of two approaches.MethodFive lower limb specimens were used in this study. After dissection of the skin and superficial fascia of each specimen, deep structures were dissected via posteromedial and posterolateral approach, and several parameters including perpendicular distance from the anterior tibial artery coursing through the interosseous membrane fissure to the lateral joint line and apex of fibular head and so on were measured and analyzed.ResultThe perpendicular distance from the ATA coursing through the interosseous membrane fissure to the lateral joint line was 49.3 ± 5.6 mm (range 41.3–56.7 mm), while the distance to the apex of fibular head was 37.7 ± 7.2 mm (range 29.0–48.0 mm). The transverse distance of the anterior tibial vascular bundle is around 10 mm. The perpendicular distance from the top accompanying vein of the ATA bundle to lateral joint line and apex of fibular head was 44.1 ± 6.3 mm and 32.5 ± 7.6 mm, respectively. The maximum proportion of posterolateral tibial plateau shielded by the fibular head from the posterior view was 61.7 ± 4.9% (range 55.6–64.1%). The average length of popliteus muscle outside the joint was 83.1 ± 6.0 mm (range 76.5–92.2 mm), and the width in the middle was 28.1 ± 4.3 mm (range 26.6–29.1 mm).ConclusionAlthough posterolateral approach seems more direct for exposure of posterolateral quadrant tibial plateau fracture, it has three major disadvantages in deep dissection. Posteromedial approach through the medial board of medial head of gastrocnemius–soleus may be safer, but it was hard for direct visualization of articular surface which limits it usage for only a few cases.

The Axillary Nerve Danger Zone in Percutaneous Fixation in the Pediatric Shoulder: The "1-Mountain-3-Valleys" Principle.

Adult literature cites an axillary nerve danger zone of 5 to 7 cm distal to the acromion tip for open or percutaneous shoulder surgery, but that may not be valid for younger patients. This study sought to quantify the course of the axillary nerve in adolescent patients with reference to easily identifiable intraoperative anatomic and radiographic parameters. A single-institution hospital database was reviewed for shoulder magnetic resonance images (MRIs) in patients 10 to 17 years old. One hundred and one MRIs from patients with a mean age of 15.6 ± 1.2 years (range, 10 to 17 years) were included. Axillary nerve branches were identified in the coronal plane as they passed lateral to the proximal humerus and were measured in relation to identifiable intraoperative surface and radiographic landmarks, including the acromion tip, apex of the humeral head, lateral physis, and central apex of the physis. The physeal apex height (i.e., 1 "mountain") was defined as the vertical distance between the most lateral point of the humeral physis (LPHP) and the central intraosseous apex of the physis. Axillary nerve branches were found in all specimens, adjacent to the lateral cortex of the proximal humerus. A mean of 3.7 branches (range, 2 to 6) were found. The mean distance from the most proximal branch (BR1) to the most distal branch (BR2) was 11.7 mm. The pediatric danger zone for the axillary nerve branches ranged from 6.6 mm proximal to 33.1 mm distal to the LPHP. The danger zone in relation to percent of physeal apex height included from 62% proximal to 242% distal to the LPHP. All branches were found distal to the apex of the physis (1 "mountain" height proximal to the LPHP). Distal to the LPHP, no branches were found beyond a distance of 3 times the physeal apex height (3 "valleys"). In children and adolescents, percutaneous fixation of the proximal humerus should be performed with cortical penetration outside of this range. These parameters serve as readily identifiable intraoperative radiographic landmarks to minimize iatrogenic nerve injury. This study provides valuable landmarks for percutaneous approaches to the proximal humerus. The surgical approach for the placement of percutaneous implants should be adjusted accordingly (i.e., performed at least 1 mountain proximal or 3 valleys distal to the LPHP) in order to prevent iatrogenic injury to the axillary nerve.

Serum creatinine to cystatin C ratio reflects preoperative and early postoperative walking ability in older patients with hip fracture.

BackgroundThe sarcopenia index (SI), calculated as the ratio of serum creatinine to cystatin C levels, reflects skeletal muscle mass and strength. Patients with hip fracture (HF) and sarcopenia have poor functional outcomes, and many require long‐term care after surgery. We hypothesized that the SI can predict preoperative and early postoperative functional outcomes.MethodsPreoperative serum creatinine and cystatin C were measured to calculate the SI for patients with surgically treated HF (n = 130, mean age: 87.8 ± 6.9 years). Walking ability before and 2 weeks after surgery was assessed, and patients were dichotomized into independent and assistance groups. To assess the validity of the SI, we examined its correlation with the quality [computed tomography (CT) value] and quantity (cross‐sectional area) of the muscles around the hip on the non‐operated side, which were preoperatively measured using CT. Receiver operating characteristic (ROC) analysis was performed to evaluate the prognostic value of the SI.ResultsThe SI of the preoperative independent (n = 77) and assistance groups (n = 53) significantly differed (70.2 ± 12.4 and 60.1 ± 9.8, respectively, P < 0.000001). At 2 weeks after surgery, the SI was significantly higher in the independent group (n = 31, 73.0 ± 14.9) than in the assistance group (n = 99, 64.0 ± 10.7, P = 0.0003). In the preoperative independent group, 28 could walk independently after surgery (SI: 74.8 ± 14.0) while 49 required assistance (SI: 67.7 ± 10.6, P = 0.01). For patients with femoral neck fracture (FNF), the SIs were significantly higher in the postoperative independent group (78.6 ± 15.7) than in the postoperative assistance group (63.2 ± 10.9, P = 0.002). Logistic regression analysis showed that the odds ratio (95% confidence interval) of the SI for postoperative walking ability was 0.95 (0.91–0.99, P = 0.03). The correlations of SIs with CT values and cross‐sectional areas were as follows: iliopsoas at the apex of the femoral head, r = 0.40, P < 0.001 and r = 0.49, P < 0.001, respectively; rectus femoris at the level of the lessor trochanter, r = 0.26, P = 0.007 and r = 0.37, P < 0.001, respectively. ROC analysis for predicting postoperative walking ability in preoperative independent patients with HF and FNF revealed areas under the curve (95% confidence interval) of 0.63 (0.50–0.76) and 0.80 (0.65–0.96), respectively.ConclusionsIn patients with HF, the SI correlated with preoperative walking ability and could predict postoperative walking ability. Among patients who could walk independently before surgery, those with high SIs could walk independently early in the postoperative period. The SI is beneficial for estimating walking ability in patients with HF.

EFFECT OF LAG-SCREW POSITIONS ON FIXATION FAILURE IN PATIENTS WITH INTERTROCHANTERIC FRACTURES OF THE FEMUR

Background: The dynamic hip screw (DHS) is widely used in treating the intertrochanteric fractures of the femur in old patients. The positions of the lag screw in the femoral neck and the distance between the tip of the lag screw and the apex of the femoral head are very important for the procedure success. Objective: To assess lag-screw positions rule on failure of fixation intertrochanteric femur fractures. Patients and Methods: This was a case presentation study contained twenty patients aged ≥50 with unstable types of intertrochanteric fractures, and had been subjected to dynamic hip screws. Results: This study included (13) females and (7) males whose ages ranged between (58) to (86) years, Failure of fixation seen in 15 cases (75%) of all cases and union seen only in 5 cases (25%). The mean tip apex distance (TAD) was significantly longer when with fixation failure (p= 0.002). Relation of Location of Lag Screw to fixation failure had no statistically significant difference. Tip apex distance(TAD)was significantly longer among the studied cases with inferior-centeral (I-C) location of lag screw as compared with centeral-centeral (C-C) location of lag screw (p= 0.006). Conclusion: The Tip apex distance (TAD) wasan easy effective way which was very important to determine the location of the screw. Regardless place of the guide-pin was placed as long as the aimed position results in a tip-apex distance of greater than twenty-five millimeters. So, it was recommended to reconsider the guide pin reduction and redirection.

Functional outcome of intertrochanteric fractures treated with proximal femoral nailing and role of tip apex distance: A retrospective study

Background: Intertrochanteric fractures of femur are one of the most commonly encountered fractures in day today orthopaedic practice. Since the introduction of proximal femoral nail, it has become an implant of choice for fixation of intertrochanteric fractures owing to their better outcomes with stable fixation and rotational stability in unstable fractures. The role of Tip-Apex Distance was clearly established with the Dynamic Hip Screw but there was inadequate data to establish the same with the use of a Proximal Femur Nail. Aims: To determine the role of tip apex distance and evaluate the functional outcome of intertrochanteric fractures treated with proximal femoral nailing. Methods: A Retrospective study of 60 patients who had intertrochanteric fractures treated with the PFN between December 2016 and December 2019. Post-operative radiographs of the affected hip in AP and Lateral view were taken and the Tip-Apex Distance was calculated in both the views by measuring the distance from the tip of the lag screw to the apex of the femoral head. Result: The Average Tip-Apex Distance was found to be 23.5mm ranging between 19 mm to 28 mm. It was noted that 6 patients had a Tip-Apex Distance of more than 25 mm and 2 patients had a Tip-Apex Distance of less than 19 mm. Conclusion: We conclude that a Tip-Apex Distance of ≤ 25 mm has a better predictive value in determining the outcome of intertrochanteric fractures treated with proximal femoral nailing.

Biomechanical analysis of arthroscopically assisted latissimus dorsi transfer fixation for irreparable posterosuperior rotator cuff tears-Knotless versus knotted anchors.

We compared the construct stability of traditional knotted techniques with modern knotless anchor systems used in arthroscopically assisted latissimus dorsi transfers (aLDTs) for irreparable posterosuperior rotator cuff tears. Eighteen cadaveric shoulders were age- and gender-matched to the following three groups: knotted group (two knotted anchors); knotless group (two knotless anchors); and triple anchor group (two knotless anchors; one all-suture anchor at the apex of the humeral head). All tendons were cyclically loaded in line of the aLDT over 400 cycles followed by a load to failure test. Outcome measures were the ultimate load to failure, elongation, construct stiffness, and failure modes. The triple anchor group revealed the highest ultimate load to failure (431 ± 78 N) compared with the knotted (326 ± 52 N; p = .022) and knotless (353 ± 105 N; p = .129) groups. Total elongation and construct stiffness were not significantly different comparing all three groups. The failure modes were: anchor pull-out in all specimen of the knotted group; three (50%) anchor pull-out and three suture pull-out in the knotless group (p = .046); four (67%) anchor pull-out, one (17%) suture pull-out and one tendon pull-out in the triple anchor group. Biomechanical analyses of knotless fixation techniques for aLDTs show similar construct stability and elongation compared with the traditional, knotted techniques. Bone fixation seems to be improved with the knotless anchor systems. In our practice, we continue to use the knotless fixation technique for aLDT and in the situation of weak, osteoporotic bone, we add a third (all-suture) anchor to improve construct stability.

Correlation between muscle mass and quality around the hip and of psoas muscles at L3 level using unenhanced CT scans.

CT segmentation of psoas muscles at L3 level is used to measure sarcopenia status, but it is not feasible when L3 is not included in the examination. We tested the correlation of psoas muscle mass and quality estimation at L3 with that of hip muscles, which could be opportunistically used in patients undergoing hip surgery. Unenhanced abdominal CT performed in 50 patients (29 males, mean/median age 69/72years) were reviewed. Regions of interest were drawn to assess cross-sectional area (CSA) and attenuation of psoas muscles at L3. These values were correlated with CSA and attenuation of iliopsoas, rectus femoris, sartorius, and tensor fascia latae at the level of the hip, separately on each side. After applying Bonferroni correction for multiple comparisons, statistical significance was set as P < .002. Attenuation of each psoas at L3 and ipsilateral hip muscles was significantly correlated (P ≤ .001, r = .491-.754). A significant correlation was observed between CSA of right psoas and ipsilateral muscles (P ≤ .00, r = .432-.525). We observed a significant correlation between CSA of left psoas and ipsilateral rectus femoris, iliopsoas, tensor fascia latae at the apex of the femoral head, and sartorius at the level of the lesser trochanter (P ≤ .001, r = .431-.502). Average time to measure CSA and attenuation of psoas muscles at L3 was 41s, that of hip muscles was 2min 12s. Measurements of mass and quality of hip muscles are feasible and correlate to those of psoas muscles at L3, being potentially used in future works on the association of sarcopenia and outcomes after hip surgery.

Traditional distance “tip-apex” vs. new calcar referenced “tip-apex” - which one is the best peritrochanteric osteosynthesis failure predictor?

IntroductionIn the treatment of trochanteric fractures, the distance between the tip of the screw and the apex of the femoral head or tip-to-apex distance (TAD) was popularized by Baumgaertner about 20 years ago as an important predictor of failure. Recently, a new reference point for determining the apex has been advocated. In this new calcar tip-to-apex (calTAD) the femoral head apex is referenced to the femoral calcar and not the center of the neck. The aim of this study is to evaluate which of these two indexes is better in predicting failure of pertrochanteric fracture fixation. Materials and MethodsWe conducted a retrospective study focusing on pertrochanteric fractures operated in our institution between 2010–2013. Radiographic measurement of both indexes was performed. Demographic information, as well as several variables with recognized influence on the rate of failure, were collected. Finally, logistic regression analysis was used to identify variables independently associated with fixation failure. ResultsA total of 463 pertrochanteric fractures were operated during this time period. One hundred and seventy cases were excluded because of early loss of follow-up (n = 143) or inadequate fluroscopic imaging (n = 27) control precluding accurate measurements. Two hundred and ninety-three fractures were included. Traditional TAD and calTAD were significantly different in the failure group: 24.9 vs. 18.0 mm (p < 0.001) and 29.2 vs. 22.6 mm (p < 0.001) respectively. No other registered variable was significantly different. Multivariate analysis confirms traditional TAD (p = 0.003; OR = 1.10) and calTAD (p = 0.002; OR = 1.12) as independent risk factors for failure. Discussion/ConclusionBoth the traditional TAD and the new calTAD have shown to be relevant indexes and independently predictive of the likelihood of failure of pertrochanteric fracture fixation. Interestingly, we found the optimal threshold for the traditional TAD to be lower (<20 mm) than the traditional cutoff (<25 mm). Our study did not confirm calTAD to be superior to the traditional TAD. From the surgical practice point of view, the authors argue that the ideal position of the screw is the central region of the femoral head (minimal traditional TAD). In case of deviation, it must be infero-central in order to maintain a low calTAD thus minimizing the risk of fixation failure.

Variations in the branching pattern of the tibial nerve in the posterior compartment of the leg

Background: Tibial nerve is the largest branch of sciatic nerve. It innervates muscles of the posterior compartment of the leg. Knowledge of the variations in motor branching pattern may help the surgeons when certain procedures are done for calf reduction and also for spastic equinus foot where selective neurectomy is required. It is also required for anesthetists for inducing neurolytic blocks. The aim of the present study was to study the variations in its branching pattern of the tibial nerve in the posterior compartment of the leg. Materials and Methods: The study was done by dissecting forty formalin-fixed lower limbs from twenty adult human cadavers. The origin of tibial nerve, variations, branching pattern, number of muscular branches and termination of the tibial nerve were studied. The level of origin of these nerves was taken in relation to the apex of head of fibula. Results: 57.5% showed that the origin was <12 cm and 42.5% were between 12 and 24 cm above the level of apex of head of fibula. The flexor hallucis longus received one branch in 70% and two branches in 30% of the specimens. Forty percent of the branches showed two or three divisions. The flexor digitorum longus received one branch in 95% and two branches in 5% of the specimens. Eighty percent of the branches of the muscle showed 2–4 divisions. 82.5% of nerve to soleus muscle had one branch and 17.5% had two branches. In 17.5% of the specimens, nerve to soleus originated from the nerve to the lateral head of gastrocnemius. Thirty percent of the branches showed 2–3 divisions. All specimens had one branch which supplied the tibialis posterior muscle and 47.5% of the branches showed 2–3 divisions. In 77.5% of the specimens, the termination occurred above the malleolar calcaneal axis. Conclusion: The flexor hallucis longus, flexor digitorum longus, and soleus muscle had one or two branches from tibial nerve. Single branch innervates tibialis posterior. Nerves to flexor hallucis longus, tibialis posterior, and the soleus had up to three divisions and nerve to flexor digitorum longus had up to four divisions.

Nanohydroxyapatite Based Ceramic Carrier Promotes Bone Formation in a Femoral Neck Canal Defect in Osteoporotic Rats.

Hip fractures are among the most common types of fracture risks in old age osteoporotic patients that often end up with immobile disabilities. Weak bones due to loss of mineral content along with an increase in the porosity of the femur neck canal in osteoporosis reduce the mechanical properties of the bone and predispose the patients to fractures. In this study, we have used calcium sulfate/nanohydroxyapatite based nanocement (NC) as carrier of recombinant human bone morphogenetic protein-2 (BMP-2), zoledronate (ZA), and bone marrow mesenchymal stromal cells (MSCs) derived exosomes (EXO) to enhance bone formation and defect healing in a femur neck canal defect model in osteoporotic rats. A cylindrical defect in the femur neck canal with dimensions of 1 mm (diameter) × 8 mm (length) starting from the lateral cortex toward the apex of the femur head was developed. The defect was impacted using NC alone or functionalized as (a) NC + ZA (systemic), (b) NC + ZA (local), (c) NC + EXO + ZA, and (d) NC + BMP + ZA to evaluate bone formation by ex vivo micro-computed tomography (micro-CT) and histological analysis 16 weeks postsurgery. Moreover, the femurs (both defect and contralateral leg) were subjected to biomechanical analysis to assess the effect of treatments on compressive mechanical properties of the bones. The treatment groups (NC + ZA (L), NC + BMP + ZA, and NC + EXO + ZA) showed enhanced bone formation with complete healing of the defect. No differences in the mechanical properties of both the defect and contralateral across the leg were observed among the groups. However, a trend was observed where NC + BMP + ZA showed enhanced biomechanical strength in the defect leg. This suggests that NC could act as a potent carrier of bioactive molecules to reduce the risks of hip fractures in osteoporotic animals. This type of treatment can be given to patients who are at higher risk of osteoporosis mediated femur neck fracture as a preventive measure or for enhanced healing in already compromised situations. Moreover, this study provided a proof of concept regarding the use of exosomes in bone regeneration therapy, which might be used as a booster dose that will eventually reduce the dosage of BMP and hence circumvent the limitations associated with the use of BMP.

Effect of ligamentum teres tear on the development of joint instability and articular cartilage damage: an in vivo rabbit study.

The contribution of the ligamentum teres to the stabilization of the hip joint and the clinical influence of a compromised ligamentum teres are not well known. This study aimed to investigate joint stability and cartilage damage in a rabbit model by surgically inducing a complete ligamentum teres tear. Twenty adult New Zealand rabbits were used in this study. Rabbits were divided into complete ligamentum teres tear with capsulotomy (n=9, group I) and capsulotomy only (n=10, group II) groups. Unilateral surgery was performed on the left hip. Joint instability was assessed by measuring the preoperative and postoperative acetabulofemoral (A-F) distances. Rabbits were euthanized to assess cartilage damage at 24weeks postoperatively. The median postoperative A-F distance of the operated side in group I [0.68cm (0.37-1.04cm)] was larger than that in group II [0.50cm (0.30-0.65cm)] (p=0.041). The median postoperative A-F distance was larger in the operated side [0.68cm (0.37-1.04cm)] compared to the nonoperated side [0.45cm (0.30-0.75cm)] in group I; it also was larger in the operated side [0.50cm (0.30-0.65cm)] compared to the nonoperated side [0.44cm (0.32-0.67cm)] in group II, but only group I showed a significant difference (p=0.016 and 0.395, respectively). Articular cartilage damage was detected at the apex of the femoral head in two rabbits (22.2%) in group I only. Rabbits with a complete ligamentum teres tear showed significant instability at the hip joint and articular cartilage damage in our rabbit model, supporting the potential clinical importance of ligamentum teres as a hip joint stabilizer.

MP06: Use of ultrasound and x-ray to predict improvement in hip osteoarthritis symptoms following intra-articular steroid injection

Introduction: Intra-articular steroid injection (IASI) is commonly used in the emergency department for management of osteoarthritis (OA) symptoms. Hip IASI carries risks, such as avascular necrosis, and there is currently no reliable way to predict long-term response of a patient’s OA to IASI. Ultrasound (US) conveniently assesses for active arthropathy by detecting effusion-synovitis, and x-ray (XR) is useful for visualizing bone-related changes. We investigated the extent that a response to hip IASI could be predicted from baseline OA patient clinical and physical features alongside US and XR imaging features. Methods: 97 consenting patients with symptomatic hip OA presenting for hip IASI were evaluated at baseline (XR and US) and again 8-weeks after IASI (US only). Self-reported pain (WOMAC), hip range of motion (ROM) were measured at baseline and follow up. On US images we quantified joint effusion and synovial thickening, i.e., “effusion-synovitis”, by the bone-capsule distance (BCD) at the apex of the femoral head from outer femoral cortex to outer synovium. On XR, we measured minimum joint space width (cm) and Kellgren-Lawrence (K-L) Grade for osteophytes and sclerotic changes. Results: In our 97 patients (43 female) aged 28-87 years (mean 59+/-13 years, K-L grades averaged 2.5+/-1.5, and US BCD averaged 5.9+/-2.0 mm. We performed multiple linear regression using age, sex, BMI, ROM of hip flexion, US BCD, radiographic joint space width and K-L grade against the dependent variable, change in WOMAC pain subscore (R=0.587, P=0.002). We compared the response predicted by this model to the actual change in WOMAC pain. At a threshold value of -20% for minimal clinically important difference, 35/97 patients were responders, and a 2x2 table gave 67% overall model predictive accuracy, 61% sensitivity, and 71% specificity. Likelihood ratio for a positive response (LR+) was 2.13. Conclusion: Combining radiographic information on structural damage, US information on active arthropathy, and demographics correctly predicted about two-thirds of the patients that would benefit from IASI after 8 weeks. A patient with hip OA that met our model criteria was more than twice as likely to respond to IASI. With further model refinement, effective, personalized evidence-based management of symptomatic hip OA is possible using XR and hip US, which could both be performed during an ER visit.

Composite spheroidal shells under external pressure

ABSTRACTBuckling, collapse, and first ply failure pressures have been obtained for a range of spheroidal FRP shells under static external pressures. Comparisons of the load carrying capacities are made for like geometries. It is shown that some prolate ellipsoids can be stronger, for up to 70% than the equivalent spheres. The effect of boundary conditions in the equatorial plane on the buckling strength is assessed for the diameter-to-wall- thickness ratio ranging from 100 to 500. Regions where the strength (FPF) rather than asymmetric bifurcation control the failure have been identified. Small perturbations in ply orientations, ±5°, have been introduced in order to assess their influence on the buckling strength. Both symmetric and asymmetric stacking with respect to the mid-plane have been analyzed (including random stacking).Initial shape imperfection positioned at the apex of a hemispherical head has been examined. The latter aimed at assessing the sensitivity of buckling pressure to deviations from perfect geometry. Results have been obtained for the lower bound approach based on the local flattening using the increased-radius. Imperfections in ellipsoids have also been studied. Axisymmetric modeling of all shells was used throughout in this study. Only the upper half of shells was modeled, and the issue of boundary conditions at the equatorial plane was also explored.

Significantly lower femoral neck growth in screw fixation of the asymptomatic contralateral hip in unilateral slipped capital femoral epiphysis.

There is an ongoing debate on which fixation technique should be preferred for the prophylactic fixation of the asymptomatic contralateral hip in slipped capital femoral epiphysis (SCFE). In the case of Kirschner-wire (K-wire) fixation, there is a possibility of secondary loss of fixation because of longitudinal growth of the physis, whereas in screw fixation, physeal growth of the femoral neck might be impaired. The aim of this matched-pair study was to compare the longitudinal growth of the femoral neck in screw fixation versus K-wire fixation of the asymptomatic contralateral hip in SCFE. All 18 patients (female:male=3:15), who had undergone screw fixation of the asymptomatic contralateral hip between 9/2001 and 9/2011, were matched according to age, bone age, sex, and time to follow-up to another 18 patients with K-wire fixation. The length of the femoral neck of the contralateral hip was measured in parallel to either screw or K-wire from the apex of the femoral head to the opposite cortical bone. The ratio of the femoral neck length measured directly after surgery and on follow-up was defined as femoral neck growth. There was no significant difference between groups with respect to age, modified Oxford Bone age score, and time to follow-up. We found a significant difference in femoral neck growth between patients with screw fixation (5.5 ± 4.3%) compared with K-wire fixation (8.9 ± 5.7%, P = 0.048 matched Wilcoxon test). The difference in femoral neck growth of patients with K-wire or screw fixation of the contralateral asymptomatic hip in SCFE was small, but statistically significant. Thus, despite high rates of secondary loss of fixation, K-wire fixation should still be considered, especially in very young patients.