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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_8 | Pages 40 - 40
11 Apr 2023
Mahdi H Hardisty M Fullerton K Huang C Vachhani K Nam D Whyne C
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µCT images are commonly analysed to assess changes in bone density and architecture in preclinical murine models. Several platforms provide automated analysis of bone architecture parameters from volumetric regions of interest (ROI). However, segmentation of the regions of subchondral bone to create the volumetric ROIs remains a manual and time-consuming task. This study aimed to develop and evaluate automated pipelines for trabecular bone architecture analysis of mouse proximal tibia subchondral bone.

A segmented dataset involving 62 knees (healthy and arthritic) from 10-week male C57BL/6 mice were used to train a U-Net type architecture, with µCT scans (downsampled) input that output segmentation and bone volume density (BV/TV) of the subchondral trabecular bone. Segmentations were upsampled and used in tandem with the original scans (10µ) as input for architecture analysis along with the thresholded trabecular bone. The analysis considered the manually and U-Net segmented ROIs using two available pipelines: the ITKBoneMorphometry library and CTan (SKYSCAN). The analyses included: bone volume (BV), total volume (TV), BV/TV, trabecular number (TbN), trabecular thickness (TbTh), trabecular separation (TbSp), and bone surface density (BSBV).

There was good agreement for bone measures between the manual and U-Net pipelines utilizing ITK (R=0.88-0.98) and CTan (R=0.91-0.98). ITK and CTan showed good agreement for BV, TV, BV/TV, TbTh and BSBV (R=0.9-0.98). However, a limited agreement was seen between TbN (R=0.73) and TbSb (R=0.59) due to methodological differences in how spacing is evaluated.

This U-Net/ITK pipeline seamlessly automated both segmentation and quantification of the proximal tibia subchondral bone. This automated pipeline allows the analysis of large volumes of data, and its open-source nature may enable the standardization of stereologic analysis of trabecular bone across different research groups.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_13 | Pages 38 - 38
1 Dec 2022
Kim J Alraiyes T Sheth U Nam D
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Thoracic hyperkyphosis (TH – Cobb angle >40°) is correlated with rotator cuff arthropathy and associated with anterior tilting and protraction of scapula, impacting the glenoid orientation and the surrounding musculature. Reverse total shoulder arthroplasty (RTSA) is a reliable surgical treatment for patients with rotator cuff arthropathy and recent literature suggests that patients with TH may have comparable range of motion after RTSA. However, there exists no study reporting the possible link between patient-reported outcomes, humeral retroversion and TH after RTSA. While the risk of post-operative complications such as instability, hardware loosening, scapular notching, and prosthetic infection are low, we hypothesize that it is critical to optimize the biomechanical parameters through proper implant positioning and understanding patient-specific scapular and thoracic anatomy to improve surgical outcomes in this subset of patients with TH.

Patients treated with primary RTSA at an academic hospital in 2018 were reviewed for a two-year follow-up. Exclusion criteria were as follows: no pre-existing chest radiographs for Cobb angle measurement, change in post-operative functional status as a result of trauma or medical comorbidities, and missing component placement and parameter information in the operative note. As most patients did not have a pre-operative chest radiograph, only seven patients with a Cobb angle equal to or greater than 40° were eligible. Chart reviews were completed to determine indications for RTSA, hardware positioning parameters such as inferior tilting, humeral stem retroversion, glenosphere size/location, and baseplate size. Clinical data following surgery included review of radiographs and complications. Follow-up in all patients were to a period of two years. The American Shoulder and Elbow Surgeons (ASES) Shoulder Score was used for patient-reported functional and pain outcomes.

The average age of the patients at the time of RTSA was 71 years old, with six female patients and one male patient. The indication for RTSA was primarily rotator cuff arthropathy. Possible correlation between Cobb angle and humeral retroversion was noted, whereby, Cobb angle greater than 40° matched with humeral retroversion greater than 30°, and resulted in significantly higher ASES scores. Two patients with mean Cobb angle of 50° and mean humeral retroversion 37.5° had mean ASES scores of 92.5. Five patients who received mean humeral retroversion of 30° had mean lower ASES scores of 63.7 (p < 0 .05). There was no significant correlation with glenosphere size or position, baseplate size, degree of inferior tilting or lateralization.

Patient-reported outcomes have not been reported in RTSA patients with TH. In this case series, we observed that humeral stem retroversion greater than 30° may be correlated with less post-operative pain and greater patient satisfaction in patients with TH. Further clinical studies are needed to understanding the biomechanical relationship between RTSA, humeral retroversion and TH to optimize patient outcomes.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_12 | Pages 58 - 58
1 Dec 2022
Lemieux V Afsharpour S Nam D Elmaraghy A
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Operative management of clavicle fractures is increasingly common. In the context of explaining the risks and benefits of surgery, understanding the impact of incisional numbness as it relates to the patient experience is key to shared decision making. This study aims to determine the prevalence, extent, and recovery of sensory changes associated with supraclavicular nerve injury after open reduction and plate internal fixation of middle or lateral clavicle shaft fractures.

Eighty-six patients were identified retrospectively and completed a patient experience survey assessing sensory symptoms, perceived post-operative function, and satisfaction. Correlations between demographic factors and outcomes, as well as subgroup analyses were completed to identify factors impacting patient satisfaction.

Ninety percent of patients experienced sensory changes post-operatively. Numbness was the most common symptom (64%) and complete resolution occurred in 32% of patients over an average of 19 months. Patients who experienced burning were less satisfied overall with the outcome of their surgery whereas those who were informed of the risk of sensory changes pre-operatively were more satisfied overall.

Post-operative sensory disturbance is common. While most patients improve, some symptoms persist in the majority of patients without significant negative effects on satisfaction. Patients should always be advised of the risk of persistent sensory alterations around the surgical site to increase the likelihood of their satisfaction post-operatively.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_13 | Pages 34 - 34
1 Dec 2022
Lapner P Pollock J Hodgdon T Sheikh A Shamloo A Fernandez AA McIlquham K Desjardins M Drosdowech D Nam D Rouleau D
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The diagnosis of infection following shoulder arthroplasty is notoriously difficult. The prevalence of prosthetic shoulder infection after arthroplasty ranges from 3.9 – 15.4% and the most common infective organism is Cutibacterium acnes. Current preoperative diagnostic tests fail to provide a reliable means of diagnosis including WBC, ESR, CRP and joint aspiration. Fluoroscopic-guided percutaneous synovial biopsy (PSB) has previously been reported in the context of a pilot study and demonstrated promising results. The purpose of this study was to determine the diagnostic accuracy of percutaneous synovial biopsy compared with open culture results (gold standard).

This was a multicenter prospective cohort study involving four sites and 98 patients who underwent revision shoulder arthroplasty. The cohort was 60% female with a mean age was 65 years (range 36-83 years). Enrollment occurred between June 2014 and November 2021. Pre-operative fluoroscopy-guided synovial biopsies were carried out by musculoskeletal radiologists prior to revision surgery. A minimum of five synovial capsular tissue biopsies were obtained from five separate regions in the shoulder. Revision shoulder arthroplasty was performed by fellowship-trained shoulder surgeons. Intraoperative tissue samples were taken from five regions of the joint capsule during revision surgery.

Of 98 patients who underwent revision surgery, 71 patients underwent both the synovial biopsy and open biopsy at time of revision surgery. Nineteen percent had positive infection based on PSB, and 22% had confirmed culture positive infections based on intra-operative tissue sampling. The diagnostic accuracy of PSB compared with open biopsy results were as follows: sensitivity 0.37 (95%CI 0.13-0.61), specificity 0.81 (95%CI 0.7-0.91), positive predictive value 0.37 (95%CI 0.13 – 0.61), negative predictive value 0.81 (95%CI 0.70-0.91), positive likelihood ratio 1.98 and negative likelihood ratio 0.77.

A patient with a positive pre-operative PSB undergoing revision surgery had an 37% probability of having true positive infection. A patient with a negative pre-operative PSB has an 81% chance of being infection-free. PSB appears to be of value mainly in ruling out the presence of peri-prosthetic infection. However, poor likelihood ratios suggest that other ancillary tests are required in the pre-operative workup of the potentially infected patient.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_14 | Pages 21 - 21
1 Nov 2021
DeBenedetti A Della Valle CJ Jacobs JJ Nam D
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The purpose of this randomized controlled trial was to evaluate serum metal ion levels in patients undergoing THA with either a standard or modular dual-mobility bearing.

Patients undergoing primary THA for osteoarthritis were randomized to receive either a modular dual-mobility or a standard polyethylene bearing. All patients received the same titanium acetabular and femoral component and a ceramic femoral head. Only patients without a prior history of metal implants in their body were eligible for inclusion, thus isolating serum metal ions to the prosthesis itself. Serum metal ion levels were drawn pre-operatively and at 1 year postoperatively. Power analysis determined that 40 patients (20 in each group) were needed to identify a clinically relevant difference in serum cobalt of 0.35 ng/ml (ppb) at 90% power assuming a pooled standard deviation of 0.31 ppb and alpha=0.05; an additional 30% were enrolled to account for potential dropouts.

53 patients were enrolled, with 22 patients in the modular dual-mobility group and 20 in the standard cohort with data available at one-year. No differences in the serum cobalt (0.17 ppb [range 0.07 to 0.50] vs. 0.19 ppb [range 0.07 to 0.62], p = 0.51) or chromium levels (0.19 ppb [range 0.05 to 0.56] vs. 0.16 ppb [range 0.05 to 0.61], p = 0.23) were identified.

At 1 year postoperatively, no differences in serum cobalt or chromium levels were identified with this design of a modular dual mobility bearing when compared to a standard polyethylene bearing.


Bone & Joint Open
Vol. 2, Issue 10 | Pages 858 - 864
18 Oct 2021
Guntin J Plummer D Della Valle C DeBenedetti A Nam D

Aims

Prior studies have identified that malseating of a modular dual mobility liner can occur, with previous reported incidences between 5.8% and 16.4%. The aim of this study was to determine the incidence of malseating in dual mobility implants at our institution, assess for risk factors for liner malseating, and investigate whether liner malseating has any impact on clinical outcomes after surgery.

Methods

We retrospectively reviewed the radiographs of 239 primary and revision total hip arthroplasties with a modular dual mobility liner. Two independent reviewers assessed radiographs for each patient twice for evidence of malseating, with a third observer acting as a tiebreaker. Univariate analysis was conducted to determine risk factors for malseating with Youden’s index used to identify cut-off points. Cohen’s kappa test was used to measure interobserver and intraobserver reliability.


The Bone & Joint Journal
Vol. 103-B, Issue 6 Supple A | Pages 51 - 58
1 Jun 2021
Yang J Heckmann ND Nahhas CR Salzano MB Ruzich GP Jacobs JJ Paprosky WG Rosenberg AG Nam D

Aims

Recent total knee arthroplasty (TKA) designs have featured more anatomical morphologies and shorter tibial keels. However, several reports have raised concerns about the impact of these modifications on implant longevity. The aim of this study was to report the early performance of a modern, cemented TKA design.

Methods

All patients who received a primary, cemented TKA between 2012 and 2017 with a minimum two-year follow-up were included. The implant investigated features an asymmetrical tibial baseplate and shortened keel. Patient demographic details, Knee Society Scores (KSS), component alignment, and the presence of radiolucent lines at final follow-up were recorded. Kaplan-Meier analyses were performed to estimate survivorship.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_5 | Pages 2 - 2
1 Mar 2021
Higuera-Rueda C Emara A Nieves-Malloure Y Klika AK Cooper H Cross M Guild G Nam D Nett M Scuderi G Cushner F Silverman R
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Aim

This was a multicenter, randomized, clinical trial to compare the 90-day 1) incidence of surgical site complications (SSC); 2) health care utilization (the number of dressing changes, readmission, and reoperation); and 3) the patient-reported outcomes (PRO) in high-risk patients undergoing revision total knee arthroplasty (rTKA) with postoperative closed incision negative pressure wound therapy (ciNPT) versus a standard of care (SOC) silver-impregnated occlusive dressing.

Method

A total of 294 rTKA patients (15 centers) at high-risk for wound complications were prospectively randomized to receive either SOC or ciNPT (n = 147 each). The ciNPT system was adjusted at 125 mmHg of suction. Investigated outcomes were assessed weekly up to 90 days after surgery. A preset interim analysis was conducted at 50% of the intended sample size, with planned discontinuation for clear efficacy/harm if a significance of p < 0.005 was attained.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_9 | Pages 66 - 66
1 Oct 2020
Yang J Heckmann ND Nahhas CR Salzano MB Ruzich GP Jacobs JJ Paprosky WG Rosenberg AG Nam D
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Introduction

Recent total knee arthroplasty (TKA) designs have featured more anatomic morphologies and shorter tibial keels. However, several reports have raised concerns regarding the impact of these modifications on implant longevity. This study's purpose is to report the early performance of a modern, cemented TKA design.

Methods

All patients who received a primary, cemented TKA from 2012 to 2017 with a minimum two-year follow-up were included. This implant features an asymmetric tibial baseplate and a shortened keel. Patient demographics, Knee Society Scores (KSS), and component alignment were recorded, and Kaplan-Meier survivorship analyses were performed.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_9 | Pages 7 - 7
1 Oct 2020
Goswami K Clarkson S Dennis DA Klatt BA O'Malley M Smith EL Pelt CE Gililland J Peters C Malkani AL Palumbo B Minter J Goyal N Cross M Prieto H Lee G Hansen E Ward D Bini S Higuera C Levine B Nam D Della Valle CJ Parvizi J
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Introduction

Surgical management of PJI remains challenging with patients failing treatment despite the best efforts. An important question is whether these later failures reflect reinfection or the persistence of infection. Proponents of reinfection believe hosts are vulnerable to developing infection and new organisms emerge. The alternative hypothesis is that later failure is a result of an organism that was present in the joint but was not picked up by initial culture or was not a pathogen initially but became so under antibiotic pressure. This multicenter study explores the above dilemma. Utilizing next-generation sequencing (NGS), we hypothesize that failures after two stage exchange arthroplasty can be caused by an organism that was present at the time of initial surgery but not isolated by culture.

Methods

This prospective study involving 15 institutions collected samples from 635 revision total hip (n=310) and knee (n=325) arthroplasties. Synovial fluid, tissue and swabs were obtained intraoperatively for NGS analysis. Patients were classified per 2018 Consensus definition of PJI. Treatment failure was defined as reoperation for infection that yielded positive cultures, during minimum 1-year follow-up. Concordance of the infecting pathogen cultured at failure with NGS analysis at initial revision was determined.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_10 | Pages 32 - 32
1 Oct 2020
Yang J Terhune EB DeBenedetti A Della Valle CJ Gerlinger TL Levine BR Nam D
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Introduction

Wound complications following revision total hip arthroplasty (THA) are associated with an increased risk of superficial and deep infections. Closed incision negative-pressure therapy (ciNPT) has been reported to decrease this risk. This study's purpose was to assess if ciNPT decreases the rate of wound complications following revision THA versus a conventional, silver-impregnated dressing.

Methods

This was a single center, randomized controlled trial of patients undergoing both septic and aseptic revision THA. Patients received either ciNPT or a silver-impregnated dressing (control) for 7 days. Wound complications within 90 days of the procedure were recorded, including: surgical site infection (SSI), periprosthetic joint infection (PJI), prolonged drainage greater than 5 days, erythema requiring antibiotics, and hematoma formation. An a priori power analysis determined 201 patients per cohort were necessary to demonstrate a 10% decrease in wound complication rate.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_6 | Pages 51 - 51
1 Jul 2020
Vachhani K Whyne C Nam D Wong J Chou J Paul R
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Rotator cuff tears are the most common cause of shoulder disability, affecting 10% of the population under 60 and 40% of those aged 70 and above. Massive irreparable rotator cuff tears account for 30% of all tears and their management continues to be an orthopaedic challenge. Traditional surgical techniques, that is, tendon transfers are performed to restore shoulder motion, however, they result in varying outcomes of stability and complications. Superior capsular reconstruction (SCR) is a novel technique that has shown promise in restoring shoulder function, albeit in limited studies. To date, there has been no biomechanical comparison between these techniques. This study aims to compare three surgical techniques (SCR, latissimus dorsi tendon transfer and lower trapezius tendon transfer) for irreparable rotator cuff tears with respect to intact cuff control using a clinically relevant biomechanical outcome of rotational motion.

Eight fresh-frozen shoulder specimens with intact rotator cuffs were tested. After dissection of subcutaneous tissue and muscles, each specimen was mounted on a custom shoulder testing apparatus and physiologic loads were applied using a pulley setup. Under 2.2 Nm torque loading maximum internal and external rotation was measured at 0 and 60 degrees of glenohumeral abduction. Repeat testing was conducted after the creation of the cuff tear and subsequent to the three repair techniques. Repeated measures analysis with paired t-test comparisons using Sidak correction was performed to compare the rotational range of motion following each repair technique with respect to each specimen's intact control. P-values of 0.05 were considered significant.

At 0° abduction, internal rotation increased after the tear (intact: 39.6 ± 13.6° vs. tear: 80.5 ± 47.7°, p=0.019). Internal rotation was higher following SCR (52.7 ± 12.9°, intact - SCR 95% CI: −25.28°,-0.95°, p=0.034), trapezius transfer (74.2 ± 25.3°, intact – trapezius transfer: 95% CI: −71.1°, 1.81°, p=0.064), and latissimus transfer (83.5 ± 52.1°, intact – latissimus transfer: 95% CI: −118.3°, 30.5°, p=0.400) than in intact controls. However, internal rotation post SCR yielded the narrowest estimate range close to intact controls. At 60° abduction, internal rotation increased after the tear (intact: 38.7 ± 14.4° vs. tear: 49.5 ± 13°, p=0.005). Internal rotation post SCR did not differ significantly from intact controls (SCR: 49.3 ± 10.1°, intact – SCR: 95% CI: −28°, 6.91°, p=0.38). Trapezius transfer showed a trend toward significantly higher internal rotation (65.7 ± 21.1°, intact – trapezius transfer: 95% CI: −55.7°, 1.7°, p=0.067), while latissimus transfer yielded widely variable rotation angle (65.7 ± 38°, intact – latissimus transfer: 95% CI: −85.9°, 31.9°, p=0.68). There were no significant differences in external rotation for any technique at 0° or 60° abduction.

Preliminary evaluation in this cadaveric biomechanical study provides positive evidence in support of use of SCR as a less morbid surgical option than tendon transfers. The cadaveric nature of this study limits the understanding of the motion to post-operative timepoint and the results herein are relevant for otherwise normal shoulders only. Further clinical evaluation is warranted to understand the long-term outcomes related to shoulder function and stability post SCR.


The Bone & Joint Journal
Vol. 102-B, Issue 6 Supple A | Pages 138 - 144
1 Jun 2020
Heckmann ND Nahhas CR Yang J Della Valle CJ Yi PH Culvern CN Gerlinger TL Nam D

Aims

In patients with a “dry” aspiration during the investigation of prosthetic joint infection (PJI), saline lavage is commonly used to obtain a sample for analysis. The aim of this study was to investigate prospectively the impact of saline lavage on synovial fluid analysis in revision arthroplasty.

Methods

Patients undergoing revision hip (THA) or knee arthroplasty (TKA) for any septic or aseptic indication were enrolled. Intraoperatively, prior to arthrotomy, the maximum amount of fluid possible was aspirated to simulate a dry tap (pre-lavage) followed by the injection with 20 ml of normal saline and re-aspiration (post-lavage). Pre- and post-lavage synovial white blood cell (WBC) count, percent polymorphonuclear cells (%PMN), and cultures were compared.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_12 | Pages 73 - 73
1 Oct 2019
Sershon RA Fillingham Y Abdel MP Malkani AL Schwarzkopf R Padgett DE Vail TP Nam D Nahhas CR Culvern C Valle CJD
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Background

The purpose of this multicenter, randomized clinical trial was to determine the optimal dosing regimen of tranexamic acid (TXA) to minimize perioperative blood loss for revision total hip arthroplasty (THA).

Methods

Six centers prospectively randomized 155 revisions to one of four regimens: 1g of intravenous (IV) TXA prior to incision, a double dose regimen of 1g IV TXA prior to incision and 1g IV TXA during wound closure, a combination of 1g IV TXA prior to incision and 1g intraoperative topical TXA, or three doses of 1950mg oral TXA administered 2 hours preoperatively, 6 hours postoperatively, and on the morning of postoperative day one. Randomization was based upon revision subgroups to ensure equivalent group distribution, including: femur only, acetabulum only, both component, explant/spacer, and second stage reimplantation. Patients undergoing an isolated modular exchange were excluded. An a priori power analysis (alpha = 0.05; beta = 0.80) determined 40 patients per group were required to identify a 1g/dL difference in postoperative hemoglobin reduction between groups. Per-protocol analysis involved an analysis of variance, Fisher's exact tests, and two one-sided t-tests for equivalence.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_11 | Pages 31 - 31
1 Oct 2019
Heckmann ND Nahhas CR Valle CJD Yi PH Culvern C Gerlinger TL Nam D
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Background

In the setting of a “dry” aspiration, saline lavage is commonly used to obtain a sample for analysis. The purpose of this study is to prospectively determine the impact of saline lavage on synovial fluid markers in revision arthroplasty.

Methods

79 patients undergoing revision hip (19) and knee (60) arthroplasty were enrolled. Intraoperatively, prior to arthrotomy, the maximum amount of fluid possible was aspirated to simulate a dry-tap (“pre-lavage”) followed by subsequent injection with 20 mL of normal saline and re-aspiration (“post-lavage”). Pre and post-lavage synovial white blood cell (WBC) count, percent polymorphonuclear cells (%PMN), and cultures were compared. Statistical analyses utilized the Wilcoxon signed-rank test.


The Bone & Joint Journal
Vol. 101-B, Issue 6_Supple_B | Pages 31 - 36
1 Jun 2019
Nam D Nunley RM Clohisy JC Lombardi AV Berend KR Barrack RL

Aims

Whether patient-reported pain differs among surgical approaches in total hip arthroplasty (THA) remains unclear. This study’s purposes were to determine differences in pain based on surgical approach (direct anterior (DA) vs posterolateral (PL)) and PL approach incision length.

Patients and Methods

This was a retrospective investigation from two centres and seven surgeons (three DA, three PL, one both) of primary THAs. PL patients were categorized for incision length (6 cm to 8 cm, 8 cm to 12 cm, 12 cm to 15 cm). All patients had cementless femoral and acetabular fixation, at least one year’s follow-up, and well-fixed components. Patients completed a pain-drawing questionnaire identifying the location and intensity of pain on an anatomical diagram. Power analysis indicated 800 patients in each cohort for adequate power to detect a 4% difference in pain (alpha = 0.05, beta = 0.80).


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_8 | Pages 44 - 44
1 May 2019
Nam D
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Surgical site infections constitute the cause of 13% to 18% of readmissions within 90 days of a total hip arthroplasty and are a leading cause of failure of revision total knee arthroplasty. The goals of wound closure are to enhance healing potential, prevent infection, and provide a cosmetic appearance. Traditionally, this has been achieved with the use of interrupted sutures. However, recently “barbed” sutures have been introduced which consist of a solid core with peripheral etched barbs in a helical array. These sutures have been used for both the deep and superficial layers of wound closure in a running fashion with the barbs intended to be self-retaining in the event that the suture is cut or pulls out of the tissue. Proposed advantages include the avoidance of knots, less needles required, improved efficiency, and creation of a “watertight” seal.

Numerous studies have shown decreased times for wound closure with the use of barbed vs. interrupted sutures with no difference in infection or complication rates. With less needles and improved efficiency, there is the potential for cost savings with the use of barbed sutures. However, there have been two studies raising concerns of arthrotomy failure with their use in total knee arthroplasty. In addition, several reports have noted the potential for increased superficial wound complications when barbed sutures are used for a subcutaneous closure. Therefore, what remains clear is that there is no proven, optimal method of wound closure in total joint arthroplasty and that every closure method remains technique dependent.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_8 | Pages 94 - 94
1 May 2019
Nam D
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Postoperative dislocation following total hip arthroplasty (THA) remains a significant concern with a reported incidence of 1% to 10%. The risk of dislocation is multifactorial and includes both surgeon-related (i.e. implant position, component size, surgical approach) and patient-related factors (i.e. gender, age, preoperative diagnosis, neurologic disorders). While the majority of prior investigations have focused on the importance of acetabular component positioning, recent studies have shown that approximately 60% of “dislocators” following primary THA have an acceptably aligned acetabular component. Therefore, the importance of the relationship between the spine and pelvis, and its impact on functional component position has gained increased attention.

Kanawade and Dorr et al. have shown patients can be categorised into having a stiff, normal, or hypermobile pelvis based on their change in pelvic tilt when moving from the standing to seated position. The degree of change in functional position of both the acetabular and femoral components is impacted by the degree of pelvic motion each patient possesses. In the “normal” pelvis, as a patient moves from the standing to seated position the pelvis typically tilts posteriorly, thus increasing the functional anteversion of the acetabular component. However, patients with lumbar degeneration or spine pathology often have a decrease in posterior pelvic tilt in the seated position, thus potentially increasing their risk of dislocation. Bedard et al. noted an 8.3% dislocation risk in patients with a spinopelvic fusion after THA vs. 2.9% in those without.

There is the potential that preoperative, dynamic imaging can be used to predict the ideal component position for each individual patient undergoing THA. However, this assumes that a patient's preoperative pelvic motion will be the same following implantation of a total hip prosthesis, and that a patient's pelvic motion will remain consistent over time postoperatively. A recent study has shown that the impact of THA on pelvic motion can be highly variable, thus potentially limiting the utility of preoperative dynamic imaging in predicting a patient's ideal component position. Future investigations must focus on preoperative factors that can be used to predict postoperative pelvic motion and how pelvic motion changes over time following implantation of a total hip arthroplasty.


The Bone & Joint Journal
Vol. 101-B, Issue 4 | Pages 365 - 371
1 Apr 2019
Nam D Salih R Nahhas CR Barrack RL Nunley RM

Aims

Modular dual mobility (DM) prostheses in which a cobalt-chromium liner is inserted into a titanium acetabular shell (vs a monoblock acetabular component) have the advantage of allowing supplementary screw fixation, but the potential for corrosion between the liner and acetabulum has raised concerns. While DM prostheses have shown improved stability in patients deemed ‘high-risk’ for dislocation undergoing total hip arthroplasty (THA), their performance in young, active patients has not been reported. This study’s purpose was to assess clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) in young, active patients receiving a modular DM acetabulum and recently introduced titanium, proximally coated, tapered femoral stem design.

Patients and Methods

This was a prospective study of patients between 18 and 65 years of age, with a body mass index (BMI) < 35 kg/m2 and University of California at Los Angeles (UCLA) activity score > 6, who received a modular cobalt-chromium acetabular liner, highly crosslinked polyethylene mobile bearing, and cementless titanium femoral stem for their primary THA. Patients with a history of renal disease and metal hardware elsewhere in the body were excluded. A total of 43 patients (30 male, 13 female; mean age 52.6 years (sd 6.5)) were enrolled. All patients had a minimum of two years’ clinical follow-up. Patient-reported outcome measures, whole blood metal ion levels (ug/l), and periprosthetic femoral BMD were measured at baseline, as well as at one and two years postoperatively. Power analysis indicated 40 patients necessary to demonstrate a five-fold increase in cobalt levels from baseline (alpha = 0.05, beta = 0.80). A mixed model with repeated measures was used for statistical analysis.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_13 | Pages 61 - 61
1 Oct 2018
Hannon CP Calkins TE Li J Culvern C Darrith B Nam D Gerlinger TL Della Valle CJ
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Introduction

Opioids are an important component of multimodal analgesia, but improper utilization places patients at risk for overdose and addiction. The purpose of this randomized controlled trial is to determine whether the quantity of opioid pills prescribed at discharge is associated with the total amount of opioids consumed or unused by patients after total hip (THA) and knee (TKA) arthroplasty.

Methods

304 Opioid naïve patients undergoing THA or TKA were randomized to receive a prescription for either 30 or 90 5mg oxycodone immediate release (OxyIR) tablets at discharge. All patients received acetaminophen, meloxicam, tramadol and gabapentin perioperatively. Daily opioid consumption, reported in morphine equivalent dose (MED), number of unused OxyIR, and pain scores were calculated for 30 days postoperatively with a patient-completed medication diary. The number of OxyIR refills and total MED received were recorded for 90 days postoperatively. Power analysis determined that 141 patients per group were necessary to detect a 25% reduction in means in opiate consumption between groups. Statistical analysis involved t-test, rank sum, and chi-squared tests with alpha=0.05.