Stem Insertion Research Articles

Weak hammering sounds are associated with postoperative subsidence in cementless total hip arthroplasty.

The aim of this study was to investigate the relationship between the hammering sound level and the presence of postoperative subsidence. The last five hammering sounds during the final-size broaching procedure and during the real stem insertion were recorded and analysed in 95 patients who were operated on by one of seven surgeons using two implants (Trident cup, Accolade II, Stryker; G7 cup, Taperloc Complete Microplasty Stem, Zimmer Biomet). The maximum peak was semi-automatically identified and analysed to determine the maximum C-weighted sound pressure level (LCpeak) of each of the five hammering sounds and the equivalent continuous A-weighted sound pressure (LAeq) of the entire five-sound hammering procedure. Among the 95 hips, 25 (26.3%) had ≥ 3mm of postoperative subsidence. Therefore, 125 of 475 hammering sounds (LCpeak) and 25 of 95 hammering procedures (LAeq) in both the broaching procedure and stem insertion procedure were associated with postoperative subsidence. The hammering sound level in both the broaching and stem insertion procedures were significantly weaker in patients with postoperative subsidence than in those without subsidence. Among the seven surgeons, there was intra-surgeon and inter-surgeon heterogeneity with large variance regarding the sound levels. With univariate and multivariate analyses, the hammering sound level was independently associated with postoperative subsidence in the two models. A weak hammering sound level was associated with postoperative subsidence in THA with a cementless stem. An objective evaluation of the hammering procedure might be useful to decrease the incidence of postoperative subsidence.

High preservation rates of the ascending branch of the lateral femoral circumflex artery during total hip arthroplasty through the direct anterior approach.

(i) To investigate the rate of preservation of the ascending branch of the lateral femoral circumflex artery (a-LFCA) during total hip arthroplasty (THA) through a direct anterior approach (DAA), and (ii) to study factors that contribute to its successful preservation. All patients who underwent primary THA between 1 September 2023 and 29 February 2024 were reviewed. One-hundred seventy-two patients were included in the study, 91 females and 81 males, aged 63.2 ± 12.6, with a body mass index of 26.1 ± 4.6 kg/m2. THA was performed through a minimally invasive DAA in all patients, using either a standard vertical DAA or a Bikini incision. Patients were stratified by the preservation of the a-LFCA (preserved, ligated/electrocauterized due to obstruction of the surgical field during dissection, electrocauterized due to bleeding during femoral broaching or stem insertion). Descriptive statistics were used to summarise the data. Logistic regression analyses were performed to explore possible factors associated with the preservation of a-LFCA. The a-LFCA was preserved in 130 patients (75.6%), had to be ligated/electrocauterized due to obstruction of the surgical field during dissection in 31 patients (18.0%), and had to be electrocauterized due to bleeding during femoral broaching or stem insertion in 11 patients (6.4%). Multivariable logistic regression analyses revealed that preservation of a-LFCA was significantly more likely in female patients (odds ratio [OR] = 2.22; 95% confidence interval [CI] = 1.1-4.6; p = 0.029), as well as in patients with younger age (OR = 0.97; 95% CI = 0.9-1.0; p = 0.036) and lower weight (OR = 0.97; 95% CI = 0.9-1.0; p = 0.005). Preservation of the a-LFCA is possible in the majority of patients (75.6%) undergoing THA through minimally invasive DAA. Furthermore, preservation of the a-LFCA is more likely in female patients, younger patients and patients with lower weight. Level IV.

TROCHANTERIC OSTEOTOMY AND TRANSFER DURING TOTAL HIP ARTHROPLASTY IN PATIENTS WITH DISLOCATED DYSPLASTIC HIPS: UNION RATE USING MONOFILAMENT TRANSVERSE WIRE CERCLAGE

Securing the osteotomized greater trochanter (GT) during total hip arthroplasty (THA) for dislocated dysplastic hips (DDH) poses a significant challenge. This study evaluates the union rate and effectiveness of a 2-strand transverse wiring technique utilizing the lesser trochanter for wire anchorage and tensioning.A digastric anterior slide trochanteric osteotomy was performed in 106 patients (118 hips) undergoing THA for DDH. Following uncemented stem insertion, the GT was transferred and fixed to the lateral cortex of the proximal femur using monofilament stainless steel wires. In 72 out of 106 patients (80 hips), the GT was fixed with 2 transverse wire cerclages threaded through 2 drill holes in the base of the lesser trochanter, spaced vertically 5–10 millimeters apart. The wires were wrapped transversely over the GT and tightened, avoiding contact with its tendinous attachments. Patients were regularly monitored, and GT union was assessed clinically and radiographically.Patient ages ranged from 20 to 57 years (mean 35.5), with a follow-up period ranging from 1.5 to 12 years (mean 6.2). The mean union time was 3.3 months (range 2–7). Among all hips, two developed stable nonunion and single wire breakage, but no fragment displacement (2.5%). Two hips exhibited delayed union, eventually healing at 6 and 7 months after surgery.Reattachment of the greater trochanter utilizing a 2-strand transverse wire cerclage anchored at the base of the lesser trochanter demonstrated a high rate of union (97.5%) following THA in dislocated DDH cases.

Mitigating calcar fracture risk with automated impaction during total hip arthroplasty

BackgroundAutomated broaching has recently been introduced for total hip arthroplasty (THA), with the goal of improving surgical efficiency and reducing surgeon workload. While studies have suggested that this technique may improve femoral sizing and alignment, little has been published regarding its safety, particularly with regard to calcar fractures. The purpose of our study was to evaluate the risk of calcar fracture during automated broaching, and to determine if this risk can be mitigated. MethodsWe queried our prospective institutional database and identified 1596 unilateral THAs performed by the senior author using automated impaction between 2019 and 2023. We identified the incidence of calcar fracture with automated impaction, and whether the fracture occurred during broaching or stem insertion. We additionally determined calcar fracture incidence within two consecutive subgroups of patients using different stem insertion techniques; subgroup (1): automated broaching with automated stem insertion for all patients; versus subgroup (2): automated broaching with automated stem insertion ONLY if a cushion of cancellous bone separated the broach from the calcar, otherwise the stem was placed manually. Continuous and categorical variables were analyzed with Student's t-test and Fisher's exact test, respectively. ResultsSeventeen calcar fractures occurred intraoperatively (1.1 %). Only two fractures occurred during automated broaching (0.1 %), while fifteen occurred during final stem impaction (0.9 %) (p = 0.007). Four calcar fractures (1.4 %) occurred in subgroup 1, compared to two in subgroup 2 (0.6 %) (p = 0.28). ConclusionsOur study found a calcar fracture incidence of 1.1 % using automated impaction, consistent with historically reported rates of 0.4–3.7 %. We found that calcar fractures are more likely to occur during stem insertion than during femoral broaching. We recommend that if any part of the final broach is in direct contact with the calcar, the final stem should be impacted manually to minimize fracture risk.

Callus formation after total hip arthroplasty using a short tapered-wedge stem.

The incidence of periprosthetic fractures after total hip arthroplasty using a short tapered-wedge stem is high. Callus formation preceding this fracture, which indicates postoperative stress fracture around the stem, has been reported. However, previous studies on postoperative callus are limited. Hence, the current study aimed to evaluate the prevalence and risk factors of postoperative callus after total hip arthroplasty with a short tapered-wedge stem. This retrospective study included 127 patients who underwent total hip arthroplasty using a cementless short tapered-wedge stem. The depth of stem insertion was measured as the distance from the lateral corner of the stem to the most medial point of the lesser trochanter along the body axis. Postoperative callus was defined as a bridging callus on the lateral femoral cortex at the distal end of the porous coating of the stem. Plain radiography was performed before surgery and immediately and at 1, 3, and 6months after surgery to assess postoperative callus. Univariate and multivariate logistic regression analyses were performed to identify the risk factors for PC. In total, 60 (47.2%) of 127 patients presented with postoperative callus. Multivariate logistic regression analysis with postoperative callus as the dependent variable revealed that the stem depth at 1month after total hip arthroplasty (odds ratio, 1.14; 95% confidence interval, 1.04-1.24, p = 0.002) was a significant and independent risk factor of postoperative callus. Deep insertion of a short tapered-wedge stem is a risk factor for postoperative callus.

Molecular and Biological Characteristics of a Peach Latent Mosaic Viroid PC Isolate in Peach from China: Base Mutations in Hairpin Stems and Implications for Symptomatology.

Peach latent mosaic viroid (PLMVd) infects peach trees in China and induces a conspicuous albino phenotype (peach calico, PC) that is closely associated with variants containing a 12-to-14 nucleotide hairpin insertion capped by a U-rich loop. Initially, PC disease distribution was limited to parts of Italy, and it was first detected in the field in China in 2019. To explore the molecular and biological characteristics of PLMVd PC isolates in peach in China, we conducted a comprehensive analysis of disease phenotype development and investigated the data-associated pathogenicity and in vivo dynamics of the Chinese isolate PC-A2 using slash-inoculation into GF-305 peach seedlings. Inoculated seedlings displayed PC symptoms much earlier following topping treatment, and PLMVd infectivity was further assessed using bioassay and semiquantitative RT-PCR experiments. Evolutionary analysis showed that the PC isolate and its progeny variants clustered into a single phylogroup distinct from reference PC-C40 isolates from Italy and PC-K1 and PC-K2 from South Korea. Some PC-A2 progeny variants from green leaves of PC-expressing seedlings showed unbalanced point mutations in hairpin stems compared with the PC-C40 reference sequence and constituted a new stem insertion type. The results reveal associations between the recessive phenotypes of peach albino symptoms and base variation in hairpin stem insertions relative to the PC-C40/chloroplastic heat shock protein 90 reference sequence.

Quasi-static mechanical evaluation of canine cementless total hip replacement broaches: effect of tooth design on broach and stem insertion

BackgroundBiomedtrix BFX® cementless total hip replacement (THR) requires the use of femoral broaches to prepare a press-fit envelope within the femur for subsequent stem insertion. Current broaches contain teeth that crush and remove cancellous bone; however, they are not particularly well-suited for broaching sclerotic (corticalized) cancellous bone. In this study, three tooth designs [Control, TG1 (additional V-grooves), TG2 (diamond tooth pattern)] were evaluated with a quasi-static testing protocol and polyurethane test blocks simulating normal and sclerotic bone. To mimic clinical broaching, a series of five sequential broach insertions were used to determine cumulative broaching energy (J) and peak loads during broach insertion. To determine the effect of broach tooth design on THR stem insertion, a BFX® stem was inserted into prepared test blocks and insertion and subsidence energy and peak loads were determined.ResultsBroach tooth design led to significant differences in broaching energy and peak broaching loads in test blocks of both densities. In low density test blocks, TG1 required the lowest cumulative broaching energy (10.76 ±0.29 J), followed by Control (12.18 ±1.20 J) and TG2 (16.66 ±0.78 J) broaches. In high density test blocks, TG1 required the lowest cumulative broaching energy (32.60 ±2.54 J) as compared to Control (33.25 ±2.16 J) and TG2 (59.97 ±3.07 J). During stem insertion and subsidence testing, stem insertion energy for high density test blocks prepared with Control broaches was 14.53 ± 0.81 J, which was significantly lower than blocks prepared with TG1 (22.53 ± 1.04 J) or TG2 (19.38 ± 3.00 J) broaches. For stem subsidence testing in high density blocks, TG1 prepared blocks required the highest amount of energy to undergo subsidence (14.49 ± 0.49 J), which was significantly greater than test blocks prepared with Control (11.09 ±0.09 J) or TG2 (12.57 ± 0.81 J) broaches.ConclusionsThe additional V-grooves in TG1 broaches demonstrated improved broaching performance while also generating press-fit envelopes that were more resistant to stem insertion and subsidence. TG1 broaches may prove useful in the clinical setting; however additional studies that more closely simulate clinical broach impaction are necessary prior to making widespread changes to THR broaches.

Bone mineral density changes around the stem correlate with stress changes after total hip arthroplasty: A study using thermoelastic stress analysis.

Thermoelastic stress analysis (TSA) was used to evaluate stress changes over the entire surface of a specimen. This study aimed to assess the relationship between femoral stress distribution, analysed using TSA and changes in bone mineral density (BMD) after total hip arthroplasty (THA). Stress changes in the simulated bone before and after taper-wedge stem insertion were measured using the TSA. Stress changes were compared with BMD changes around the stem 1 year after surgery in a THA patient (58 hips) with the same taper-wedge stem. Subsequently, we compared the correlation between stress changes and BMD changes. TSA revealed significant stress changes before and after stem insertion, with prominent alterations in the proximal medial region. The BMD changes at 1 year post-THA exhibited a 15%-25% decrease in the proximal zones, while Zones 2-6 showed a -6% to 3% change. Notably, a strong positive correlation (0.886) was found between the stress change rate and BMD change rate. This study demonstrated a high correlation between femoral stress distribution assessed using TSA and subsequent BMD changes after THA. The TSA method offers the potential to predict stress distribution and BMD alterations postsurgery, aiding in implant development and clinical assessment. Combining TSA with finite element analysis could provide even more detailed insights into stress distribution. Case series (with or without comparison).

Effect of longer femoral head on leg length, offset, and range of motion in total hip arthroplasty: a simulation study

In this study, we investigated the relationship between head length, leg length, offset, and dislocation resistance using range of motion (ROM) simulations based on computed tomography data to examine if a longer femoral head reduces the risk of dislocation. The femoral components were set to eliminate leg length differences with a + 0 mm head, and variations for + 4-, + 7-, and + 8-mm heads were analyzed. Offset and ROM were assessed when longer heads were used, with the leg length adjusted to be similar to that of the contralateral side. While internal rotation at flexion and external rotation at extension increased with + 4-mm longer heads, the + 7- and + 8-mm heads did not increase dislocation resistance. When adjusting for leg length, the longer heads showed no significant differences in offset and ROM. Enhancing dislocation resistance by solely increasing the offset with a longer head, while simultaneously adjusting the depth of stem insertion, may be a beneficial intraoperative technique. Although a + 4-mm longer head possibly increases ROM without impingement, heads extended by + 7 or + 8 mm may not exhibit the same advantage. Therefore, surgeons should consider this technique based on the implant design.

Biomechanical Effect of Bone Variables and Implant Position on Femoral Damage Mechanism in Total Hip Arthroplasty

The impact of bone variables, including density, geometry, angle of femoral torsion, and thickness of the femoral cortices, on the formation of bone micro-damage following THA was investigated. Using CT images of avascular necrosis patients, we developed 28 intact femoral bone models with ages ranging from 19 to 87 years to explore the relationship between age and bone density. Among these 28 femur models, 10 models were selected for implantation with the Zweymuller stem, divided into two groups based on the highest and lowest bone mineral density (BMD). After proper stem insertion into the femoral bone canal, finite element analyses with nonlinear damage analysis were performed on the THA models under three boundary conditions: stance, lateral bending, and torsion. Using the Pearson’s correlation coefficient, the study revealed a strong correlation between bone density and fracture load in the 10 THA models, which remained consistent across all three boundary conditions: stance (r = 0.74), lateral bending (r = 0.79), and torsion (r = 0.88). However, a moderate correlation was observed between bone density and the number of solid element failures, which also remained consistent across all boundary conditions: stance (r = -0.40), lateral bending (r = -0.51), and torsion (r = -0.48). It was found that femoral models with a bent shape of the femoral shaft and thin cortices experienced greater bone damage compared to models with normal geometry. Additionally, THA models with retroversion stem placement resulted in higher bone damage compared to models with normal anteversion placement.

Risk factors for templating mismatch of uncemented stems in bipolar hemiarthroplasty for femoral neck fracture

Preoperative templating needs to be precise to optimize hip arthroplasty outcomes. Unexpected implant mismatches can occur despite meticulous planning. We investigated the risk factors for oversized and undersized stem mismatch during uncemented hemiarthroplasty using a double-tapered wedge rectangular stem for femoral neck fracture. Out of 154 consecutive patients who underwent hemiarthroplasty for femoral neck fracture, 104 patients were divided into three groups: (1) oversized (n = 17; 16.3%), (2) matched (n = 80; 76.9%), and (3) undersized stem group (n = 7; 6.7%). A smaller femoral head offset (odds ratio [OR] = 0.89, 95% confidence interval [95% CI] = 0.81–0.98, P = 0.017), smaller isthmus diameter (OR = 0.57, 95% CI = 0.35–0.92, P = 0.021), and smaller canal flare index (OR = 0.20, 95% CI = 0.04–0.98, P = 0.047) were significantly associated with oversized stem insertion, while older age (OR = 1.18, 95% CI = 1.01–1.39, P = 0.037) was associated with undersized stem insertion in logistic regression. In conclusion, when performing hemiarthroplasty for a femoral neck fracture with a double-tapered wedge rectangular stem, surgeons must pay close attention to proximal femoral geometry and patient age during preoperative planning to avoid stem mismatch.

Stem alignment with short tapered-wedge cementless stems affects bone mineral density continuously for at least 5 years after primary total hip arthroplasty.

This study aimed to assess the relationship between the three-dimensional (3D) alignment of short tapered-wedge cementless stems and bone mineral density (BMD) changes in patients followed up for 5 years after total hip arthroplasty (THA). We retrospectively analysed the hips of 52 patients who underwent THA using short tapered-wedge cementless stems at our institution from 2013 to 2016 with complete 5-year follow-up data. We evaluated the relationship between stem alignment, measured using a 3D-templating software, and BMD changes in the 7 Gruen zones. After 1 year, significant negative correlations between varus insertion and a decrease in BMD in zone 7 and between flexed insertion and decreases in BMD in zones 3 and 4 were noted. After 5 years, significant negative correlations between varus insertion and a decrease in BMD in zone 7 and between flexed insertion and decreases in BMD zones 2, 3, and 4 were observed. With increased amounts of varus/flexion stem alignment, the amount of BMD loss decreased. There was no correlation between anteverted stem insertion and changes in BMD levels. Our data showed that stem alignment affects BMD based on 5-year follow-up data after surgery. Careful observation is necessary, especially when using short tapered-wedge cementless stems, as stem alignment may affect changes in BMD levels more than 5 years after surgery.

Patients With Shorter Stature Exhibit Minimal Hammering Sound Changes During Cementless Stem Insertion in Total Hip Arthroplasty.

Listening to the change in the hammering sound is 1 of the elements used to assess the cementless stem stability. This study aimed to quantitatively investigate the change in the acoustic characteristics between the early and late phases of cementless stem insertion in total hip arthroplasty and to identify which patient characteristics contribute to the change in the hammering sound. The acoustic parameters of the hammering sounds in the early and late phases of cementless taper-wedged stem insertion for 51 hips in 45 patients who underwent total hip arthroplasty (mean age= 68 years, height= 1.56 m, weight= 55.0 kg) were analyzed. Parameters including patient's basic characteristics, radiographical femoral morphology, and canal fill ratio were assessed as potential contributors to the change in the hammering sound. The low-frequency bands (0.5-1.0 kHz and 1.0-1.5 kHz) showed the largest changes during stem insertion and were therefore considered key bands for the analysis of sound alterations. Multivariate linear regression analysis showed that height (β= 8.312, P= .013) and proximal canal fill ratio (β=-3.8568, P= .038) were independently associated with the sound alterations. The decision tree analysis identified height (≥1.66 m or <1.66 m) as the best single discriminator for the sound alteration. Patients with smaller stature showed the least change in the hammering sound during stem insertion. Understanding the acoustic characteristics of hammering sound alteration during cementless stem insertion may aid in the achievement of optimal stem insertion.

Not all screens are created equal: examination of surface features and other physical properties of commonly used screen materials for smoking drugs

BackgroundBrass screens are considered an essential part of the safer drug smoking/inhalation supplies and are widely distributed by harm reduction programs in Canada. However, the use of commercially available steel wools as screens for smoking crack cocaine remains a common practice among people who smoke drugs in Canada. Use of these steel wool materials is associated with different adverse effects on health. This study aims to determine what changes folding and heating have on several filter materials, including brass screens and commercially available steel wool products, and examine the implications of these changes on health of people who smoke drugs.MethodsThis study investigated the microscopic differences, studied by optical and scanning electron microscopy, between four screen and four steel wool filter materials used in a simulated drug consumption process. New materials were manipulated, compacted into its own Pyrex® straight stem using a push stick and then heated with a butane lighter simulating a common method in preparing drugs for consumption. The materials were studied in the as-received (new), as-pressed (compressed and inserted into the stem tube but without heating) and as-heated (compressed and inserted into the stem tube and heated with a butane lighter) conditions.ResultsThe steel wool materials with the smallest wire thicknesses were found to be the easiest to prepare for pipe use, but degrade significantly during shaping and heating, making them wholly unsuitable as a safe filter material. In contrast the brass and stainless steel screen materials remain mostly unchanged by the simulated drug consumption process. After the stainless steel pellet screen, the Brass Impact 2.0 screen material had the best characteristics of the materials tested due to its mesh wire diameter, pitch, alloy choice and its pre-strained state.ConclusionCommonly used steel wool alternatives degrade during the handling and stem insertion, and heating the screens in the stem. Debris is generated by wool deformation on insertion and after heating that easily separates from the screen and can be inhaled during drug consumption. The brass and stainless steel screen materials are safer to use as they remain mostly stable during the simulated drug consumption process.

INCIDENCE AND MANAGEMENT OF INTRAOPERATIVE FRACTURES OCCURRING AROUND THE HIP DURING PRIMARY TOTAL HIP ARTHROPLASTY: A SYSTEMATIC REVIEW

Intraoperative fractures although rare are one of the complications known to occur while performing a total hip arthroplasty (THA). However, due to lower incidence rates there is currently a gap in this area of literature that systematically reviews this important issue of complications associated with THA.Method: We looked into Electronic databases including PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), the archives of meetings of orthopaedic associations and the bibliographies of included articles and asked experts to identify prospective studies, published in any language that evaluated intra-operative fractures occurring during total hip arthroplasty from the year 1950-2020. The screening, data extraction and quality assessment were carried out by two researchers and if there was any discrepancy, a third reviewer was involved.Fourteen studies were identified. The reported range of occurrence of fracture while performing hip replacement surgery was found to be 0.4-7.6%. Major risk factors identified were surgical approaches, Elderly age, less Metaphyseal-Diaphyseal Index score, change in resistance while insertion of the femur implants, inexperienced surgeons, uncemented femoral components, use of monoblock elliptical components, implantation of the acetabular components, patients with ankylosing spondylitis, female gender, uncemented stems in patients with abnormal proximal femoral anatomy and with cortices, different stem designs, heterogeneous fracture patterns and toothed design.Intraoperative fractures during THA were managed with cerclage wire, femoral revision, intramedullary nail and cerclage wires, use of internal fixation plates and screws for management of intra operative femur and acetabular fractures.The main reason for intraoperative fracture was found to be usage of cementless implants but planning and timely recognition of risk factors and evaluating them is important in management of intraoperative fractures. Adequate surgical site exposure is critical especially during dislocation of hip, reaming of acetabulum, impaction of implant and preparing the femoral canal for stem insertion. Eccentric and increased reaming of acetabulum to accommodate a larger cup is to be avoided, especially in females and elderly patients as the acetabulum is thinner. However, this area requires more research in order to obtain more evidence on effectiveness, safety and management of intraoperative fractures during THA.

Factors associated with humeral stem revision in anatomic to reverse total shoulder arthroplasty revision

Recent advances in implant technology have allowed for modular or platform humeral stem insertion during initial anatomic total shoulder arthroplasty (TSA). These systems allow for humeral stem retention during conversion to reverse TSA (RTSA). However, some patients still require humeral stem revision when undergoing revision to RTSA. The purpose of this study was to evaluate the association between patient-specific factors and radiographic parameters with humeral stem revision vs. retention during conversion from TSA to RTSA. Retrospective chart review was conducted for patients who underwent a revision TSA to RTSA between January 2010 and May 2022 at a single institution. Patients were included if their prosthesis included a convertible humeral stem. Patient demographic information, surgical details, and postoperative outcomes and complications were collected. Radiographic parameters were measured by 2 graders on radiographs taken prior to the revision procedure. The need for humeral stem revision and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores (preoperative and 2 years) were also noted. Statistical analysis was performed using chi-square test for categorical variables and t test for continuous variables. One hundred seven patients were included, with 52 undergoing humeral stem revision. Patients were revised an average of 51.0±54 months after primary TSA. Younger patient age (63.6 vs. 68.5 years, P=.017) and use of a lateralized glenosphere (1.6 mm vs. 0.4 mm, P<.001) were significantly associated with need for humeral stem revision. Glenoid to humeral head cut distance (28.3 mm vs. 26.3 mm, P=.076) approached significant association with the need for humeral stem revision. All other measurements were not associated with the need for humeral stem revision. Improvement of ASES scores at 2 years' follow-up was higher in the nonrevised group (increase of 33.4 points) than the revision group (23.3), but this did not reach significance (P=.149). Estimated blood loss and surgical time were significantly higher in the stem revision group than the non-revised group (P=.048 and P<.001, respectively). Younger patients and those receiving a lateralized glenosphere were more likely to undergo humeral stem revision during conversion from TSA to RTSA. Glenoid to the humeral head cut distance should be studied further as a potential indication for humeral stem revision, as it correlates with the space available for a revision implant. This information can guide surgeons with preoperative planning for a revision arthroplasty.

The Impact of Varying Femoral Head Length on Hip External Rotation During Posterior-approach Total Hip Arthroplasty

BackgroundPrior investigations of total hip arthroplasty (THA) have studied the effects of prosthetic femoral head size and stem offset on hip range of motion (ROM), impingement risk, and overall hip stability to optimize the return to activities of daily living. However, the relationship between femoral head length and hip ROM, specifically external rotation (ER), has not been evaluated. The aim of our study was to intraoperatively assess how femoral head length affects hip ROM during a posterior approach THA. MethodsThirty-two patients undergoing a primary elective THA through a posterior approach were prospectively included. After final femoral stem insertion, femoral head trials were performed using the targeted head length, followed by the shorter (−3.0 to −3.5 mm) and longer (+3.0 to +4.0 mm) head length configurations. At each length, hip ER was measured using an intraoperative goniometer from an imageless navigation system. ER values across the three head lengths were compared using a repeated-measures analysis of variance and paired t-tests. ResultsVarying femoral head lengths demonstrated a statically significant and reproducible effect on intraoperative ER range (analysis of variance; P < .001) in each patient. An increased femoral head length (mean 3.4 mm) significantly decreased (P < .001) ER range by 10.8 ± 3.3° while a shortened femoral head length (mean 3.5 mm) significantly increased (P < .001) the ER ROM by 6.0 ± 3.8°. ConclusionsThe results of this study demonstrate the sensitivity of hip ROM to incremental changes in femoral head length. As ER is important for activities of daily living, inadvertent lengthening should be avoided.

Influence of the biomechanical environment on the femoral stem insertion and vibrational behavior: a 3-D finite element study.

The long-term success of cementless surgery strongly depends on the implant primary stability. The femoral stem initial fixation relies on multiple geometrical and material factors, but their influence on the biomechanical phenomena occurring during the implant insertion is still poorly understood, as they are difficult to quantify in vivo. The aim of the present study is to evaluate the relationship between the resonance frequencies of the bone-implant-ancillary system and the stability of the femoral stem under various biomechanical environments. The interference fit IF, the trabecular bone Young's modulus [Formula: see text] and the bone-implant contact friction coefficient [Formula: see text] are varied to investigate their influence on the implant insertion phenomena and on the system vibration behavior. The results exhibit for all the configurations, a nonlinear increase in the bone-implant contact throughout femoral stem insertion, until the proximal contact is reached. While the pull-out force increases with [Formula: see text], IF and [Formula: see text], the bone-implant contact ratio decreases, which shows that a compromise on the set of parameters could be found in order to achieve the largest bone-implant contact while maintaining sufficient pull-out force. The modal analysis on the range [2-7] kHz shows that the resonance frequencies of the bone-implant-ancillary system increase with the bone-implant contact ratio and the trabecular bone Young's modulus, with a sensitivity that varies over the modes. Both the pull-out forces and the vibration behavior are consistent with previous experimental studies. This study demonstrates the potential of using vibration methods to guide the surgeons for optimizing implant stability in various patients and surgical configurations.

A Simple Device to Determine Ante-Version During Femoral Prosthesis Insertion in Total Hip Replacement

Introduction: Good outcomes in Total Hip Replacement (THR) depend upon correct component alignment. This is influenced by the surgeon’s capacity to recreate a geometrically normal and biomechanically stable hip joint. Mal-positioining of components can lead to various complications and the surgeons have to make vital decisions intra-operatively based on their experience. Materials and Methods: This study describes a simple instrument to aid alignment of femoral stem insertion and hence achieve the normal range of ante-version between 10 º-20 º. Experiments performed on a saw bone model by twenty orthopaedic surgeons, each making six attempts to insert a prosthesis demonstrated improved positioning when compared to unaided insertion. Results: The mean average femoral stem ante-version unaided was 18.3 º (range, 4.9 º to 36.6 º). Device aided ante-version was 14.4 º (range, 9.8 º to 18.9 º) (p&lt;0.001). We also report the practicality of the use of the device which was assessed by use on cadavers. Conclusion: Precise assessment of stem ante-version can be achieved in non-navigated THR if such a device is available intra-operatively.

Intraoperative Acoustics: Auditory Cues in Hip Reconstructive Surgery.

Orthopaedic surgeons rely on visual and tactile cues to guide performance in the operating room (OR). However, there is very little data on how sound changes during orthopaedic procedures and how surgeons incorporate audio feedback to guide performance. This study attempts to define meaningful changes in sound during vital aspects of total hip arthroplasty (THA) within the spectrum of human hearing. 84 audio recordings were obtained during primary elective THA procedures during sawing of the femoral neck, reaming of the acetabulum, acetabular cup impaction, polyethylene liner impaction, femoral broaching, planning of the femoral calcar and press-fit of a porous-coated stem in 14 patients. We graphed changes in frequency intensity across the human spectrum of hearing and sampled frequencies showing differences over time for statistically meaningful changes. Sawing of the femoral neck, polyethylene impaction, and stem insertion showed significant temporal increases in overall sound intensity. Calcar planing showed a significant decrease in sound intensity. Moreover, spectrographic analysis showed that, for each of the critical tasks in THA, there were characteristic frequencies that showed maximal changes in loudness. These changes were above the 1 dB change in intensity required for detection by the human ear. Our results clearly demonstrate reproducible sound changes during total hip arthroplasty that are detectable by the human ear. Surgeons can incorporate sound as a valuable source of feedback while performing total hip arthroplasty to guide optimal performance in the OR. These findings can be extrapolated to other orthopaedic procedures that produce characteristic changes in sound. Moreover, it emphasizes the importance of limiting ambient noise in the OR that might make sound changes hard to distinguish.