Normative Values for Daily Functional Recovery Patterns Following Total Knee Arthroplasty.

BACKGROUND: Wearable devices provide the ability for clinical teams to continuously monitor patients' rehabilitation progress with objective data. Understanding expected recovery patterns following total knee arthroplasty (TKA) enables prompt identification of patients failing to meet these milestones. The aim of this study was to establish normative values for daily functional recovery in the first 6 weeks after TKA using a wearable device. METHODS: This prospective study included patients who underwent TKA between 2020 and 2023, treated by 11 surgeons from 8 institutions. Eligible participants were aged 18 or older, had a primary unilateral TKA, and owned a smartphone. Knee range of motion, total daily steps, cadence, and device usage were measured continuously over 6 weeks. Statistical analysis included analysis of variance using post hoc Tukey honest significant difference tests. RESULTS: The cohort of 566 participants had a mean age of 65 and 69 for men and women, respectively (range, 50 to 80). Women comprised 61% (n = 345) of study participants. There were 82% of women and 90% of men who had a body mass index > 30. The average daily wear time of the device was 12 hours (±4) for a total of 45 days (±27). Recovery was nonlinear, with the greatest gains in the first 3 weeks postsurgery for all metrics. Men demonstrated greater total daily step counts and cadence when compared to women. Obese patients demonstrated poorer performance when compared to lower body mass index patients. CONCLUSIONS: To our knowledge, this study presents the first normative data for tracking daily functional recovery in TKA patients using wearable sensors. Standardizing the TKA recovery timeline allows surgeons to isolate factors affecting patients' healing processes, accurately counsel them preoperatively, and intervene more promptly postoperatively when rehabilitation is not within standard recovery parameters.

A Novel Irrigant to Eliminate Planktonic Bacteria and Eradicate Biofilm Superstructure With Persistent Effect During Total Hip Arthroplasty.

BACKGROUND: Numerous studies have examined the use of topical and irrigation-related adjuvants to decrease the risk of periprosthetic joint infection (PJI) after total hip arthroplasty. Many issues related to their use remain to be investigated. These include cost, antibiotic stewardship, bactericidal effect on planktonic bacteria, host cytotoxicity, necessity to irrigate/dilute potentially cytotoxic agents after their application, and impact on biofilm. METHODS: Bacterial strains of microorganisms were grown in optimal medium. After the growth phase, the organisms were exposed to the novel irrigation solution (XPerience) or phosphate buffer solution (PBS) for 5 minutes before a neutralizing broth was added. The colony-forming units per milliliter and the log reduction in colony-forming units in the treated sample vs the control were then determined. Subsequently, biofilms of microorganisms were grown on hydroxyapatite-coated glass slides. Each slide was then exposed to irrigation solutions for various contact times. Biofilm quantification was performed and the log10 density of each organism was obtained. RESULTS: In vitro testing of the irrigant demonstrated 6-log reductions in planktonic bacteria in 5 minutes, and 4-log to 8-log reductions in biofilms. Laboratory tissue testing has demonstrated minimal cytotoxic effects to host tissue allowing for solution to remain in contact with the host without need for subsequent irrigation, creating a barrier to biofilm for up to 5 hours after its application. CONCLUSION: This novel irrigant demonstrates high efficacy against both planktonic bacteria and bacterial biofilms in laboratory testing. Large series in vivo data are necessary to further establish its efficacy in reducing primary and recurrent surgical site infections.

Which Tibial Tray Design Achieves Maximum Coverage and Ideal Rotation: Anatomic, Symmetric, or Asymmetric? An MRI-based study.

Two goals of tibial tray placement in TKA are to maximize coverage and establish proper rotation. Our purpose was to utilize MRI information obtained as part of PSI planning to determine the impact of tibial tray design on the relationship between coverage and rotation. MR images for 100 consecutive knees were uploaded into PSI software. Preoperative planning software was used to evaluate 3 different tray designs: anatomic, symmetric, and asymmetric. Approximately equally good coverage was achieved with all three trays. However, the anatomic compared to symmetric/asymmetric trays required less malrotation (0.3° vs 3.0/2.4°; P < 0.001), with a higher proportion of cases within 5° of neutral (97% vs 73/77%; P < 0.001). In this study, the anatomic tibia optimized the relationship between coverage and rotation.

Evaluating the Precision of Preoperative Planning in Patient Specific Instrumentation: Can a Single MRI Yield Different Preoperative Plans?

If PSI preoperative planning were perfectly precise, a single MRI would give rise to one preoperative plan. Our purpose was to determine whether a single MRI inputted into two different PSI software yielded differences in preoperative alignment determination, component sizing, and bone resection within the preoperative plan. This prospective comparative study evaluated 40 preoperative plans generated by two PSI software given identical MRI. Femoral and tibial component sizes differed between software in 37.5% and 30.0% of cases, respectively. The maximum difference in bone resection between software ranged from 2.2mm to 5.1mm. Surgeons should be prepared to intraoperatively deviate from PSI selected size by 1 size. It may be necessary to fine tune soft tissue balancing when using a PSI system.

Short stem metaphyseal-engaging femoral implants: a case-controlled radiographic and clinical evaluation with eight year follow-up.

A prospective comparison of 148 hips in 139 consecutive patients treated with an off-the-shelf uncemented metaphyseal engaging (91-105 mm) stem and 69 hips in 61 patients treated with a custom uncemented metaphyseal engaging short stem was conducted to evaluate the mid-term clinical and radiographic results of an off-the-shelf metaphyseal-engaging short stem implant. All implants were radiographically stable with proximal bony in-growth. There was no significant difference in post-operative HHS (P <. 001) or WOMAC scores (P < .001) between cohorts. An off-the-shelf short femoral stem designed to fit and fill the metaphysis provides reliable fixation up to eight years with equivalent clinical and radiographic results to a customized implant.

Does Implant Design Influence the Accuracy of Patient Specific Instrumentation in Total Knee Arthroplasty?

PSI software adjusts preoperative planning to accommodate differences in implant design. Such adjustments may influence the accuracy of intraoperative jig placement, bone resection, or component placement. Our purpose was to determine whether implant design influences PSI accuracy. 96 and 123 PSI TKA were performed by a single surgeon using two different implant systems and identical PSI software. Femoral coronal alignment outliers were greater for Implant 1 (23.9% Implant 1 vs. 13.4% Implant 2; P=0.050). Tibial coronal alignment outliers were greater for Implant 2 (10.9% Implant 1 vs. 22.7% Implant 2; P=0.025). There was no difference in overall mechanical axes. Differences in implant design can influence bone resection and component alignment. PSI software rationale must align with surgeons' intraoperative goals.

Femoral component rotation in total knee arthroplasty: an MRI-based evaluation of our options.

Proper femoral component rotation is crucial in successful total knee arthroplasty. Rotation using anatomic landmarks has traditionally referenced the transepicondylar axis (TEA), Whiteside's Line (WSL), or posterior condylar axis (PCA). TEA is thought to best approximate the flexion-axis of the knee, however WSL or PCA are common surrogates in the operating room. This study evaluated 560 knees using MRI-based planning software to assess the relationship of WSL and PCA to the TEA and determine if the relationships were influenced by pre-operative coronal deformity. Results showed the WSL-TEA relationship has more variability than PCA-TEA and that the PCA is more internally rotated in females and valgus knees. Axis options and historical assumptions about axis relationships may need to be reassessed as imaging technology advances.

Understanding readmission after primary total hip and knee arthroplasty: who's at risk?

Readmission has been cited as an important quality measure in the Patient Protection and Affordable Care Act. We queried an electronic database for all patients who underwent Total Hip Arthroplasty or Total Knee Arthroplasty at our institution from 2006 to 2010 and identified those readmitted within 90 days of surgery, reviewed their demographic and clinical data, and performed a multivariable logistic regression analysis to determine significant risk factors. The overall 90-day readmission rate was 7.8%. The most common readmission diagnoses were related to infection and procedure-related complications. An increased likelihood of readmission was found with coronary artery disease, diabetes, increased LOS, underweight status, obese status, age (over 80 or under 50), and Medicare. Procedure-related complications and wound complications accounted for more readmissions than any single medical complication.

How accurately are we coding readmission diagnoses after total joint arthroplasty?

Readmission rates have been cited as an important quality measure in the Affordable Care Act. Accordingly, understanding and accurately tracking the causes for readmission will be increasingly important. We queried an electronic database for all patients who underwent primary THA or TKA at our institution from 2006 through 2010. We identified those readmitted within 90 days of surgery and analyzed 87 random de-identified medical records. We then assigned a clinical diagnosis for each readmission, which was then compared with the coder-derived diagnosis by ICD-9 code. The overall 90-day readmission rate was 7.9%. We identified 22 of 87 patients for whom there was disagreement (25.3%, 95% CI=16.6-35.8%). The most common were procedure-related complications. Coded diagnoses frequently did not correlate with the physician-derived diagnoses. The unverified use of coded readmission diagnoses in calculating quality measures may not be clinically relevant.

Stable fixation of short-stem femoral implants in patients 70 years and older.

BACKGROUND: Limitations of conventional uncemented femoral stems persist, including proximal-distal mismatch, nonideal load transfer, loss of bone, and difficulties with minimally invasive surgery. Metaphyseal-engaging short-stem implants have been designed to address these issues in THA. While these devices have been studied in younger patients, it is unclear whether they offer advantages in older patients. QUESTIONS/PURPOSES: We asked whether the stability and bony ingrowth of an off-the-shelf short stem in patients 70 years and older were similar to those achieved in patients younger than 70 years at 2-year followup. Furthermore, we asked whether pain and function scores were affected by age, bone quality, or varus alignment. PATIENTS AND METHODS: We retrospectively reviewed 60 patients (65 hips) 70 years and older (mean, 75 years; range, 70-86 years) treated with an uncemented short stem (range, 90-105 mm). We compared radiographic alignment, stability, and bony ingrowth, as well as Harris hip scores and WOMAC pain scores, to a cohort of 89 patients (91 hips) younger than 70 years. Minimum followup was 24 months (mean, 35 months; range, 24-60 months). RESULTS: Radiographs showed proximal bony ingrowth and stable fixation of all implants. Average Harris hip score at last followup was 88 (range, 70-100) for the 70 years and older cohort and 93 (range, 70-100) for younger than 70 years cohort; no patients reported thigh pain. Postoperative WOMAC scores averaged 6 (range, 0-43) and 5 (range, 0-25), respectively. CONCLUSIONS: Short-stem implants provide solid, dependable fixation in osteoporotic bone at minimum 2-year followup, while meeting some of the limitations in conventional primary THA. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

A monoblock porous tantalum acetabular cup has no osteolysis on CT at 10 years.

BACKGROUND: Aseptic osteolysis has been the single most important factor limiting the longevity of a THA. A great deal of attention has been focused on the development of implants and materials that minimize the development of osteolysis. The monoblock porous tantalum acetabular cup was designed to minimize osteolysis, but whether it does so is unclear. QUESTIONS/PURPOSES: We evaluated the incidence of osteolytic lesions after THA using a monoblock porous tantalum acetabular component. METHODS: We retrospectively reviewed 51 patients who had a THA using a monoblock porous tantalum acetabular cup. At a minimum of 9.6 years postoperatively (average, 10.3 years; SD, 0.2 years; range, 9.6-10.8 years), a helical CT scan of the pelvis using a metal suppression protocol was obtained. This scan was evaluated for the presence of osteolysis. RESULTS: We found no evidence of osteolysis on CT scan at an average of 10.3 years. CONCLUSIONS: Osteolysis appears not to be a major problem at 10 years with this monoblock porous tantalum acetabular component, but longer term followup will be required to determine whether these findings persist. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Patient-Reported Outcomes After Total Hip Arthroplasty in a Low-Resource Country by a Visiting Surgical Team.

BACKGROUND: Total hip arthroplasty (THA) is a highly successful procedure but limited in many low-resource nations. In response, organizations globally have conducted service trips to provide arthroplasty care to underserved populations. Few outcomes data are currently available related to these trips. Our study aims to demonstrate the feasibility of tracking patient-reported outcomes and complications after THA in a low-resource setting and that outcomes are comparable to those in developed countries. METHODS: We completed an arthroplasty service trip to Brazil in 2017 where we performed 46 THAs on 38 patients. The mean patient age was 48.8 years. Forty-seven percent were female. Patient-reported outcome scores were collected preoperatively and postoperatively at 2, 6, and 12 weeks and 1 year. A multivariate regression analysis was performed to identify associations between patient factors and 12-week outcomes. RESULTS: The mean modified Harris Hip Score, Hip Disability and Osteoarthritis Outcome Score, Patient-Reported Outcome Measurement Information System Short Form (PROMIS-SF) Pain Interference, and PROMIS-SF Physical Function all improved significantly compared to baseline at 2, 6, and 12 weeks and 1 year postoperatively. At 1 year, only 29% of patients (11 of 38) were reachable by phone for follow-up.Multivariate regression analysis at 12 weeks found that females had more improvement in Hip Disability and Osteoarthritis Outcome Score for Joint Replacement scores (P = .003) and PROMIS-SF Pain Interference scores (P = .01) than males, and patients with rheumatoid arthritis had more improvement in PROMIS-SF Pain Interference scores (P = .008) compared with all other diagnoses. CONCLUSION: Patients in low-resource countries benefitted significantly from THA performed by a visiting surgical team. However, following up patients is difficult in low-resource countries once they leave the hospital.

Radiographic and navigation measurements of TKA limb alignment do not correlate.

UNLABELLED: Precise pre- and postoperative anatomic measurements are necessary to plan, perform, and evaluate total knee arthroplasty (TKA). We evaluated the relationship between radiographic and navigation alignment measurements, identified sources of error in radiographic and navigated alignment assessment, and determined the differences between desired and clinically accepted alignment. Fifty-eight computer-assisted TKAs were performed and limb alignment measurements were recorded both pre- and postoperatively with standard radiographs and with an intraoperative navigation system. Intraoperative navigation produced consistent navigation-generated alignment results that were within 1 degrees of the desired alignment. The difference between preoperative radiographic and navigation measurements varied by as much as 12 degrees and the difference between postoperative radiographic and navigation measurements varied by as much as 8 degrees. This discrepancy depended on the degree of limb deformity. Postoperative radiographic measurements have inherent limitations. Navigation can generate precise, accurate, and reproducible alignment measurements. This technology can function as an effective tool for assessing pre- and postoperative limb alignment and relating intraoperative alignment measurements to clinical and functional outcomes. LEVEL OF EVIDENCE: Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Intra-Articular Vancomycin Powder Eliminates Methicillin-Resistant S. aureus in a Rat Model of a Contaminated Intra-Articular Implant.

BACKGROUND: Periprosthetic joint infection following hip and knee arthroplasty leads to poor outcomes and exorbitant costs. Topical vancomycin powder has been shown to decrease infection in many procedures such as spine surgery. The role of vancomycin powder in the setting of total joint arthroplasty remains undefined. Our aim was to evaluate the efficacy of intra-articular vancomycin powder in preventing infection in a rat model of a contaminated intra-articular implant. METHODS: Thirty-two female Sprague-Dawley rats underwent knee arthrotomy and implantation of a femoral intramedullary wire with 1 mm of intra-articular communication. The knee joint was also inoculated with 1.5 × 10 colony forming units (CFU)/mL of methicillin-resistant Staphylococcus aureus (MRSA). Four treatment groups were studied: (1) no antibiotics (control), (2) preoperative systemic vancomycin, (3) intra-articular vancomycin powder, and (4) both systemic vancomycin and intra-articular vancomycin powder. The animals were killed on postoperative day 6, and distal femoral bone, joint capsule, and the implanted wire were harvested for bacteriologic analysis. Statistical analyses were performed using Wilcoxon rank sum and Fisher exact tests. RESULTS: There were no postoperative deaths, wound complications, signs of vancomycin-related toxicity, or signs of systemic illness in any of the treatment groups. There were significantly fewer positive cultures in the group that received vancomycin powder in combination with systemic vancomycin compared with the group that received systemic vancomycin alone (bone: 0% versus 75% of 8, p = 0.007; Kirschner wire: 0% versus 63% of 8, p = 0.026; whole animal: 0% versus 88% of 8, p = 0.01). Only animals that received both vancomycin powder and systemic vancomycin showed evidence of complete elimination of bacterial contamination. CONCLUSIONS: In a rat model of a contaminated intra-articular implant, use of intra-articular vancomycin powder in combination with systemic vancomycin completely eliminated MRSA bacterial contamination. Animals treated with systemic vancomycin alone had persistent MRSA contamination. CLINICAL RELEVANCE: This animal study presents data suggesting that the use of intra-articular vancomycin powder for reducing the risk of periprosthetic joint infections should be investigated further in clinical studies.

Minimally invasive navigated knee surgery: an American perspective.

Minimally invasive total knee replacement surgery may make it possible for patients to undergo the procedure with less pain and recover from the surgery more quickly than has been previously possible. However, minimally invasive techniques have the potential for being associated with a number of complications, including implant and limb malalignment. Computer-assisted technologies used in conjunction with minimally invasive techniques allow the accuracy with which the procedures are performed to be retained.

The Role of Potentially Retrievable Inferior Vena Cava Filters in High-Risk Patients Undergoing Joint Arthroplasty.

INTRODUCTION: Some patients undergoing total joint arthroplasty are at increased risk for venous thromboembolism (VTE). The aim of the present study was to evaluate the safety and efficacy of prIVCF in preventing PE in patients undergoing joint replacement surgery who are at high-risk for VTE. MATERIALS AND METHODS: In this prospective, IRB-approved study, prIVCF were placed in consecutive patients who met specific high-risk criteria (history of VTE or hypercoaguable state) prior to total joint arthroplasty. Patients were followed until the IVC filter was removed. Outcomes and complications were recorded per Society of Interventional Radiology guidelines. RESULTS: One hundred and nine potentially retrievable IVC filters were placed in 105 patients, who all subsequently underwent joint arthroplasty. One hundred eight IVC filters (98.9%) were retrieved successfully in a mean time of 44.1 days (range 13-183 days). There was 1 failed IVC filter retrieval attempt (0.9%) at 46 days post implantation. Two patients (1.9%) presented with recurrent PE and were successfully treated with anticoagulation prior to IVC filter retrieval. There were no fatalities from perioperative PE. In 1 patient (0.9%), a fractured filter leg had embolized during retrieval. CONCLUSION: Potentially retrievable IVC filters are safe and effective for prophylaxis against PE in patients at high-risk for VTE undergoing joint arthroplasty.

Radiographically Silent Loosening of the Acetabular Component in Hip Arthroplasty.

Polyethylene wear and subsequent osteolysis are major obstacles to the long-term success of total hip arthroplasty (THA). We conducted a study to determine the incidence of loose acetabular components that did not show frank signs of loosening on either plain radiography or computed tomography (CT), or radiographically silent loosening (RSL). In this retrospective study, we evaluated patients who underwent revision THA and were evaluated with plain radiography and CT between 2000 and 2012. Any patient with imaging that showed signs of component movement was excluded. Of the 104 patients who met the study inclusion criteria, 17 (16.3%) met the criteria for RSL of the acetabular shell. Patients with RSL presented at a similar age (P = .961) and with a similar sex profile (P = .185) compared with patients with stable acetabular components and were more likely to present with pain (P = .0487). Acetabular components may be loose even if there is no evidence of component migration on radiographic studies. Surgeons should be aware of the incidence of RSL and the potential of RSL to affect patient care and potential surgical options.

Use of helical computed tomography for the assessment of acetabular osteolysis after total hip arthroplasty.

BACKGROUND: Acetabular osteolysis is a major problem affecting long-term survival of total hip prostheses. Since lytic lesions may be asymptomatic until extensive bone loss has occurred, early detection of lytic lesions is important. The purposes of this study were to determine the efficacy and potential role of high-resolution helical (or spiral) computed tomography with metal-artifact minimization in the early detection of osteolysis of the pelvis and to use the method to determine if there was a relationship between the extent of osteolysis and the amount of polyethylene wear. METHODS: Forty patients (fifty hips) who had undergone primary cementless total hip arthroplasty between 1988 and 1994 were evaluated as part of an ongoing prospective study. These patients had a history of high-level activity that was believed to place them at increased risk for accelerated polyethylene wear. The most recent follow-up radiographs were compared with the three-month postoperative radiographs. Helical computed tomography scans with metal-artifact minimization were made, and evidence of osteolytic lesions on these scans was compared with that on the radiographs. Two-dimensional wear analysis was performed with use of digitized radiographs, and the results were compared with loss of bone volume as calculated from the computed tomography scans. RESULTS: Acetabular lysis was identified on the radiographs of sixteen hips and on the computed tomography scans of twenty-six hips. Radiographs underestimated the extent of the lysis in thirteen of the sixteen hips. There was no correlation (r = 0.036) between linear wear and the measured volume of bone loss, with the numbers available. On the basis of the amount of lysis seen on the computed tomography scans, one patient underwent a revision procedure. CONCLUSIONS: Helical computed tomography with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis after total hip arthroplasty than is plain radiography. Since computed tomography scans show both the extent and the location of lytic lesions, they are useful to guide treatment decisions as well as to assist in planning for surgical intervention, when needed, in patients with suspected osteolysis.

The rationale for short uncemented stems in total hip arthroplasty.

Uncemented femoral implants of various designs have proved to provide stable initial and long-term fixation in patients who undergo total hip arthroplasty. Challenges in primary total hip arthroplasty have led to the evolution of short stem designs. These challenges include proximal/metaphyseal and distal/diaphyseal mismatch; facilitation of less-invasive surgical exposures, especially the direct anterior approach; and bone preservation for potential revision surgery.

Clinical, functional, and radiographic outcomes following total knee arthroplasty with patient-specific instrumentation, computer-assisted surgery, and manual instrumentation: a short-term follow-up study.

PURPOSE: The purpose of this study was to evaluate clinical, functional, and radiographic outcomes following total knee arthroplasty (TKA) performed with patient-specific instrumentation (PSI), computer-assisted surgery (CAS), and manual instruments at short-term follow-up. METHODS: 122 TKAs were performed by a single surgeon: 42 with PSI, 38 with CAS, and 40 with manual instrumentation. Preoperative, 1-month, and 6-month clinical and functional outcomes were measured using the Knee Society scoring system (knee score, function score, range of motion, and pain score). Improvements in clinical and functional outcomes from the preoperative to postoperative period were analyzed. Preoperative and postoperative radiographs were measured to evaluate limb and component alignment. RESULTS: Preoperative, 1-month postoperative, and 6-month postoperative knee scores, function scores, range of motion, and pain scores were highest in the PSI group compared to CAS and manual instrumentation. At 6-month follow-up, PSI TKA was associated with a statistically significant improvement in functional score when compared to manual TKA. Otherwise, there were no statistically significant differences in improvements among PSI, CAS, and manual TKA groups. CONCLUSION: The higher preoperative scores in the PSI group limits the ability to draw definitive conclusions from the raw postoperative scores, but analyzing the changes in scores revealed that PSI was associated with a statistically significant improvement in Knee Society Functional score at 6-month post-TKA as compared to CAS or manual TKA. This may be attributable to improvements in component rotation and positioning, improved component size accuracy, or other factors that are not discernible on plain radiograph.