Does Artificial Intelligence Outperform Humans Using Fluoroscopic-Assisted Computer Navigation for Total Hip Arthroplasty?

Background: Successful total hip arthroplasty (THA) relies on the correct implant position. THA accuracy can be improved with the use of intraoperative fluoroscopic-assisted computer navigation. Artificial intelligence (AI) software may enhance fluoroscopic navigation; however, the accuracy of the AI compared to human-controlled software in assessing acetabular component position and leg length discrepancy (LLD) has not been studied. Methods: We analyzed 420 consecutive primary THAs performed by a single surgeon using fluoroscopic-assisted computer navigation software. The first cohort of 211 patients required inputs from a human technician (manual), while the second cohort of 209 patients used an automated version of the software controlled by AI. The intraoperative acetabular component placement (inclination and anteversion) and LLD were recorded and compared to the 2-week postoperative standing anterior-posterior pelvis radiograph. Results: Ninety-four percent (199/211) of cups in the manual cohort and 95% (198/209) of cups in the AI cohort were within the Lewinnek "safe-zone" (P = 1.0). In the manual cohort, 69% (146/211) of THAs had a final LLD within ±2 mm of the intraoperatively navigated LLD (ie, ΔLLD ≤2 mm). In the AI cohort, 66% (137/209) of THAs had a final LLD within ±2 mm of the intraoperatively navigated LLD (P = .47). Ninety-nine percent (209/211) of hips in the manual cohort and 98% (205/209) of hips in the AI cohort had a final LLD within ±5 mm of the intraoperatively navigated LLD (P = .45). Conclusions: Both AI and human-controlled versions of the same navigation platform were similarly accurate for navigating cup position within the Lewinnek "safe zone" and LLD accuracy.

Fluoroscopy-Assisted Computer Navigation Accurately Determines Cup Position and Leg Length for Anterior Hip Arthroplasty.

BACKGROUND: Recently, fluoroscopy-assisted computer navigation has been developed to assess intraoperative cup inclination/anteversion and leg-length discrepancy (LLD) in the operating room. However, there is a relative dearth of studies investigating the accuracy of this software compared with postoperative radiographs. MATERIALS AND METHODS: We prospectively enrolled 211 navigated anterior total hip arthroplasties using fluoroscopy-assisted computer navigation software. Intraoperative navigated measurements were compared with postoperative anteroposterior radiographs to assess accuracy of cup inclination/anteversion and LLD. Continuous variables were analyzed using the Student's t test, and categorical variables were analyzed using Fisher's exact test. RESULTS: On postoperative radiographs, 94.3% of cups (199 of 211) were positioned within the Lewinnek "safe zone," compared with 99.1% navigated intraoperatively (P=.01). Eighty-two percent of hips (174 of 211) were navigated intraoperatively to LLDs within ±2 mm; on postoperative radiographs, 65% of hips (138 of 211) had LLDs within ±2 mm (P=.0001). Intraoperatively, 100% of hips (211 of 211) were navigated to LLDs within ±5 mm; similarly, on postoperative radiographs, 98% of hips (207 of 211) had LLDs within ±5 mm (P=.12). CONCLUSION: A novel fluoroscopy-assisted computer navigation platform accurately assessed intraoperative cup position and LLD during anterior total hip arthroplasty. Careful attention to fluoroscopic technique, positioning of radiographic landmarks, and knowledge of the limitations of fluoroscopy, including parallax effect, are important concepts that surgeons should incorporate into their decision algorithm. [Orthopedics. 202x;4x(x):xx-xx.].

Posterior Capsule Reconstruction with Polypropylene Mesh After Total Hip Arthroplasty.

Instability remains a challenge after total hip arthroplasty (THA). We have previously utilized a monofilament polypropylene mesh to reconstruct the posterior capsule for unstable THA. This study identified 24 hips that underwent mesh reconstruction of the posterior capsule for instability. Survivorship was 70.8% at mean 6.5 years (range 6 weeks-20.1 years). Six patients underwent re-operation, and one patient had the mesh removed. Of eight hips, five (62.5%) with a history of prior revision re-dislocated, while only 2/16 hips (12.5%) with no previous revision history re-dislocated (p = 0.02). Posterior capsule reconstruction with polypropylene mesh has reasonable mid-term survivorship in this challenging population. (Journal of Surgical Orthopaedic Advances 32(2):092-096, 2023).

Handheld Navigation Improves Accuracy in Direct Anterior Total Hip Replacement.

Background: This study sought to determine the accuracy in placing the acetabular component, estimation of leg length, offset, radiation time and dose, and operative time using a handheld navigation device compared to conventional anterior total hip arthroplasty (THA). It also examined the learning curve of the handheld navigation device. Methods: Data were prospectively collected for a consecutive series of 159 THAs; 99 THAs with handheld navigation and 60 conventional THAs. Thresholds of <5°, ≥5° to <10°, and ≥10° for acetabular inclination and version and thresholds of <5 mm, ≥5 mm to <10 mm, and ≥10 mm for leg-length and combined offset discrepancy were used to assess accuracy. Fluoroscopy time and exposure, operative time, and complications were compared. Learning curve was determined using operative time. Statistical analysis was performed for the different accuracy thresholds with P values set a <0.05 for significance. Results: The handheld navigation device demonstrated a mean accuracy of 3.2° and 1.8° for version and inclination, respectively. The handheld navigation group had significantly fewer outliers in version (P < .001), inclination (P < .001), leg-length discrepancy (P < .001), and offset discrepancy (P < .001). Fluoroscopic dose and time (P < .001) were lower in the handheld navigation cohort. The learning curve for handheld navigation was 31-35 cases. The mean operative time after the learning curve was similar to that in the conventional fluoroscopy group (P = .113). Conclusions: Handheld navigation technology provided more accurate results while mitigating radiation exposure to the surgeon and patient. There were fewer outliers in the handheld navigation group. After the learning curve, all metrics improved in accuracy, and operative time was similar to that of the conventional technique.

Total Hip Arthroplasty in Patients With Severe Chronic Pubic Diastasis.

Background: Total hip arthroplasty (THA) in patients with severe chronic pubic diastasis from either congenital or acquired causes presents an exceptionally difficult challenge that has rarely been addressed in the arthroplasty literature. The purpose of this paper is to present a series of THAs in patients with severe chronic pubic diastasis, asking the following research questions: (1) What is the survivorship and clinical outcomes after THA in patients with severe chronic pubic diastasis? And (2) What is the rate of complications after THA surgery in this challenging patient population? We additionally describe our algorithm for preoperative planning and rationale for surgical technique and implant position. Material and methods: We retrospectively queried the prospective arthroplasty database of 2 high-volume referral centers, yielding 6 THA in 4 patients with severe chronic pubic diastasis (minimum 8 cm) with a mean follow-up of 2.7 years. We recorded baseline demographic and intraoperative variables, as well as survivorship, patient-reported outcomes (Hip disability and Osteoarthritis Outcome Score for Joint Replacement score), and incidence of complications. Results: There were no failures reported (100% survivorship) at a mean follow-up of 2.7 years. Mean Hip disability and Osteoarthritis Outcome Score for Joint Replacement scores improved from 36.0 preoperatively to 82.8 postoperatively. There were no infections, dislocations, fractures, or any major complications in the postoperative period. Conclusion: THA for patients with severe chronic pubic diastasis remains a rare but challenging reconstructive procedure. Excellent outcomes can be achieved with adequate preparation, particularly regarding the acetabular component position. Understanding the nature of the hemipelvis deformity and meticulous templating using "normalized" views of the hip are important components to a successful preoperative plan.

Is Dislocation Risk due to Posterior Pelvic Tilt Reduced With Direct Anterior Approach Total Hip Arthroplasty?

BACKGROUND: Pelvic tilt affects acetabular anteversion, and thus total hip arthroplasty (THA) dislocation risk. The pubic symphysis-sacrococcygeal distance (PSCD) is an indicator of pelvic tilt, and a PSCD < 0 mm (ie, excessive posterior pelvic tilt) is associated with a 3.7-fold increase in postoperative dislocation rate. However, it is not known if the direct anterior (DA) approach might reduce this dislocation rate, specifically in high-risk populations such as negative PSCD. METHODS: Standing anteroposterior radiographs were reviewed for 510 consecutive DA THAs to determine PSCD. Patients were separated into 2 groups: (1) PSCD > 0 mm (PSCD[+]) and (2) PSCD < 0 mm (PSCD[-]). Incidence of dislocation was determined. We recorded if patients had spinal deformity or lumbar fusion. Continuous variables were analyzed using Student's t-test, categorical variables were analyzed using Fisher's exact test, and a sample size calculation was performed. RESULTS: Three hundred fifty-eight hips (70.2%) were PSCD[+], while 152 hips (29.8%) were PSCD[-]. Three dislocations (3/510 hips, 0.6%) occurred. Two dislocators were in the PSCD[-] group (2/152 hips, 1.3%) and 1 dislocator was in the PSCD[+] group (1/358 hips, 0.3%) (P = .21). Twenty-four patients had degenerative scoliosis (24/510, 4.7%), of which 1 had a dislocation (1/24, 4.2%); 2 dislocations occurred in nonscoliosis patients (2/486, 0.4%) (P = .134). Twenty-seven patients had lumbar spinal fusion (27/510, 5.3%), of which there were no dislocations (0/27, 0.0%); all dislocations were in nonfusion patients (3/483, 0.6%) (P = 1.0). CONCLUSION: We demonstrate no increased risk for THA dislocation in patients with a PSCD < 0 mm who have undergone a DA approach. These data would suggest a protective effect of the DA approach against dislocation, even in historically high-risk populations.

Decreased costs with maintained patient satisfaction after total joint arthroplasty in a physician-owned hospital.

OBJECTIVE: Comparing total joint arthroplasty (TJA) costs and patient-reported outcomes between a physician-owned hospital (POH) and a non-POH. METHODS: Costs for each 90-day TJA episode at both facilities were determined, and patients were asked to complete a patient satisfaction questionnaire. RESULTS: Average TJA episode cost was $19,039 at the POH, compared to $21,302 at the non-POH, a difference of $2,263 (p = 0.03), largely driven by decreased skilled nursing facility utilization in the POH group. There were no differences between groups for patient satisfaction. CONCLUSION: TJA can be performed at reduced cost with comparable patient satisfaction at POHs, compared to non-POH facilities.

Accelerometer-based navigation improves early patient-reported outcomes after gap-balanced total knee arthroplasty.

OBJECTIVE: To investigate the effect of accelerometry-based navigation (ABN) on early clinical outcomes after TKA. METHODS: 71 TKAs were performed via ABN and 37 TKAs via standard instrumentation (STD). Patients were assessed at the second post-operative visit to determine early KOOS, JR scores. RESULTS: At average 2.7 months, mean KOOS, JR in the ABN group was 68.5 (range 34.2-100) compared to 62.5 (range 20.9-84.6) in the STD group (p = 0.045). Tourniquet time averaged 65.2min (range 51-79min) in STD group, compared with 70.7min (range 53-108min) in ABN group (p = 0.029). CONCLUSION: Early KOOS, JR scores are improved with ABN for TKA.

Acetabular Exposure Is Enhanced With Self-Retaining Retractors During Direct Anterior Total Hip Arthroplasty.

Acetabular exposure for direct anterior (DA) total hip arthroplasty (THA) can be performed using hands-free, self-retaining retractors. No current study quantitatively compares this self-retaining technique with the traditional manual technique. In 65 consecutive DA THA hips, two "best-view" digital photographs were taken of the exposure-one using Charnley/self-retaining retractors and one using a traditional three-retractor manual technique. Percent exposure of the polyethylene liner was calculated. Percent acetabular exposure averaged 80.0% using the Charnley/self-retaining technique, compared with 73.1% using the manual technique (P=.0002). A hands-free technique provides superior acetabular exposure compared with the manual technique. Increasing body mass index predicts decreasing exposure with both techniques. [Orthopedics. 2021;44(2):e309-e313.].

Triaging Total Hip Arthroplasty During the COVID-19 Pandemic.

PURPOSE OF REVIEW: The purpose of this review was to evaluate the available literature to determine what may be considered urgent indications for total hip arthroplasty, in the unprecedented setting of the worldwide COVID-19 pandemic. RECENT FINDINGS: SARS-CoV-2 is a novel coronavirus currently presenting in the form of a global pandemic, referred to as COVID-19. In this setting, multiple states have issued executive orders prohibiting "elective" surgery, including arthroplasty, in order to preserve healthcare resources. However, during this unprecedented reduction in elective surgery, there is likely to be some controversy as to what constitutes a purely "elective" procedure, versus an "urgent" procedure, particularly regarding hip arthroplasty. We reviewed the available literature for articles discussing the most commonly encountered indications for primary, conversion, and revision hip arthroplasty. Based upon the indications discussed in these articles, we further stratified these indications into "elective" versus "urgent" categories. In patients presenting with hip arthroplasty indications, the decision to proceed urgently with surgery should be based upon (a) the potential harm incurred by the patient if the surgery was delayed and (b) the potential risk incurred by the patient in the context of COVID-19 if surgery was performed. The authors present a decision-making algorithm for determining surgical urgency in three patients who underwent surgery in this context. Urgent total hip arthroplasty in the setting of the COVID-19 pandemic is a complex decision-making process, involving clinical and epidemiological factors. These decisions are best made in coordination with a multidisciplinary committee of one's peers. Region-specific issues such as hospital resources and availability of PPE may also inform the decision-making process.

Surgical automation reduces operating time while maintaining accuracy for direct anterior total hip arthroplasty.

OBJECTIVE: Investigate the efficiency/accuracy of surgical automation versus manual component implantation in DA THA. METHODS: Retrospective review of 111 hips: 51 hips via automation and 60 hips via manual technique for DA THA. RESULTS: OR time averaged 8 min faster in the Automated group, compared to Manual group (p = 0.0009). Average femoral size was one size larger in the Automated group compared to Manual group (p = 0.007). No clinically significant differences were found between Manual and Automated groups for cup position or limb-length discrepancy. One calcar fracture occurred in the Automated group. CONCLUSION: Surgical automation is efficient and accurate for DA THA.

Financial impact of removal of total knee arthroplasty from the inpatient-only list for a physician-owned BPCI program.

OBJECTIVE: Assessing financial effects of removal of TKA from CMS inpatient-only list on physician-owned bundles. METHODS: We determined whether Medicare TKAs remained inpatient, versus changed to observational. We used CMS data to determine savings. Direct costs associated with BPCI were calculated. RESULTS: 7/28 TKAs (25.0%) had inpatient status changed to observational, excluding them from BPCI. Estimated savings losses were $24,332. Direct costs for administrating BPCI were $51,250. Had the rate of patients changed to observational been 50%, bundle savings from remaining patients would be less than direct costs. CONCLUSION: Removing TKA from CMS inpatient-only list may have negative financial implications.

Defining hypercalciuria in nephrolithiasis.

The classic definition of hypercalciuria, an upper normal limit of 200 mg/day, is based on a constant diet restricted in calcium, sodium, and animal protein; however, random diet data challenge this. Here our retrospective study determined the validity of the classic definition of hypercalciuria by comparing data from 39 publications analyzing urinary calcium excretion on a constant restricted diet and testing whether hypercalciuria could be defined when extraneous dietary influences were controlled. These papers encompassed 300 non-stone-forming patients, 208 patients with absorptive hypercalciuria type I (presumed due to high intestinal calcium absorption), and 234 stone formers without absorptive hypercalciuria; all evaluated on a constant restricted diet. In non-stone formers, the mean urinary calcium was well below 200 mg/day, and the mean for all patients was 127±46 mg/day with an upper limit of 219 mg/day. In absorptive hypercalciuria type I, the mean urinary calcium significantly exceeded 200 mg/day in all studies with a combined mean of 259±55 mg/day. Receiver operating characteristic curve analysis showed the optimal cutoff point for urinary calcium excretion was 172 mg/day on a restricted diet, a value that approximates the traditional limit of 200 mg/day. Thus, on a restricted diet, a clear demarcation was seen between urinary calcium excretion of kidney stone formers with absorptive hypercalciuria type I and normal individuals. When dietary variables are controlled, the classic definition of hypercalciuria of nephrolithiasis appears valid.

Wound pharmacobiology.

Wound healing after major joint surgery involves a series of complex events. Over the past several years, thrombin has emerged as a pivotal participant in wound healing. The high incidence of venous thromboembolism following major joint replacement has made prophylaxis with pharmacologic agents a component of postoperative management. Anticoagulant agents of various classes affect different degrees of thrombin inhibition by virtue of their in vivo mechanisms of action. By inhibiting thrombin activity directly, with or without antithrombin III or other antithrombins, traditional anticoagulants may retard the wound healing process and impair completion. Newer, more selective anticoagulants may provide not only more effective alternatives for venous thromboembolism prophylaxis surrounding major orthopedic procedures, but also an anticoagulant environment more favorable to wound healing.

Fondaparinux, a synthetic pentasaccharide: the first in a new class of antithrombotic agents - the selective factor Xa inhibitors.

Despite currently available antithrombotic therapies, venous thromboembolism (VTE) remains a major cause of morbidity and mortality. Fondaparinux sodium (pentasaccharide), the first in a new class of antithrombotic agents developed for the prevention and treatment of VTE, inhibits thrombin generation by selectively inhibiting factor Xa. Fondaparinux exhibits complete bioavailability by the subcutaneous route and is rapidly absorbed, reaching its maximum concentration approximately 2 h post dosing. It has a terminal half-life of 13 to 21 h, permitting once-daily dosing. Fondaparinux's reproducible linear pharmacokinetic profile exhibits minimal intrasubject and intersubject variability, suggesting that individual dose adjustments will not be required for the vast majority of the population and that there will be no need for routine hemostatic monitoring. At therapeutic concentrations (<2 mg/L), fondaparinux exhibits >94% binding to its target protein, antithrombin. Within this same concentration range there is no specific binding by fondaparinux to plasma proteins commonly involved in drug binding, indicating a low potential for drug-drug interactions by protein displacement. Unlike antithrombotic agents prepared from animal extracts (heparins), fondaparinux is chemically synthesized; this leads to batch-to-batch consistency and the absence of potential risk of contamination problems. In recently completed phase III clinical trials in VTE prevention in major orthopedic surgery, fondaparinux showed significant superiority over the low-molecular-weight heparin enoxaparin, providing an overall >50% (P < 0.001) reduction in VTE risk without increasing clinically important bleeding. Additional clinical data support its potential benefits in other venous and arterial thrombotic disorders. In view of these collective findings, fondaparinux is expected to play a major role in the prevention and treatment of venous and arterial thrombotic disease.