Use of a monoblock dual-mobility acetabular component in primary total hip arthroplasty in patients at high risk of dislocation

INTRODUCTION

Dislocation is amongst the most common complications following total hip arthroplasty (THA). Dual-mobility bearings have been suggested as one way to reduce the risk of dislocation, particularly among patients at increased risk. The purpose of this study was to determine the outcomes of a monoblock dual-mobility shell for patients at high risk for dislocation following primary THA.

METHODS

A total of 155 primary THAs with a monoblock, cementless dual-mobility acetabular component were performed in patients at high risk for dislocation. Two patients died prior to their two-year follow-up. The remaining 153 THAs were followed for a mean of 5.1 years (range: 2.1 to 9.3).

RESULTS

There were no dislocations; however, four patients underwent revision surgery: one for an early periprosthetic acetabular fracture, one for an early periprosthetic femoral fracture, one for a late periprosthetic femoral fracture, and one for leg-length discrepancy. Intraoperative complications included one periprosthetic acetabular fracture treated with protected weight-bearing and one intraoperative proximal femoral fracture treated with cerclage wiring. Harris Hip Scores improved from a mean of 42.4 points preoperatively to a mean of 82.4 points postoperatively (p < 0.001). No cups were radiographically loose. At a mean follow-up of 5.1 years, survivorship of the acetabular component was 99.3% (95% CI, 98.1-100%) and survivorship without any reoperation was 97.4% (95% CI, 95.9-100%).

DISCUSSION

Although there were no dislocations in this high-risk population, periprosthetic fractures of the femur and acetabulum were common with the implants utilised.

Frailty Is Associated With Increased 30-Day Adverse Events and Hospitalization Costs After Primary Total Hip Arthroplasty

BACKGROUND

Frailty can predict adverse outcomes for multiple medical conditions and surgeries but is not well studied in total hip arthroplasty (THA). We evaluate the association between Hospital Frailty Risk Score and postoperative events and costs after primary THA.

METHODS

Using the National Readmissions Database, we identified primary THA patients for osteoarthritis, osteonecrosis, or hip fracture from January to November 2017. Using Hospital Frailty Risk Score, we compared 30-day readmission rate, hospital course duration, and costs between frail and nonfrail patients for each diagnosis, controlling for covariates. Thirty-day complication and reoperation rates were compared using univariate analysis.

RESULTS

We identified 167,700 THAs for osteoarthritis, 5353 for osteonecrosis, and 7246 for hip fractures. Frail patients had increased 30-day readmission rates (5.3% vs 2.5% for osteoarthritis, 7.1% vs 3.3% for osteonecrosis, 8.4% vs 4.3% for fracture; P < .01), longer hospital course (3.4 vs 1.9 days for osteoarthritis, 4.1 vs 2.1 days for osteonecrosis, 6.3 vs 3.9 days for fracture; P < .01), and increased costs ($18,712 vs $16,142 for osteoarthritis, $19,876 vs $16,060 for osteonecrosis, $22,185 vs $19,613 for fracture; P < .01). Frail osteoarthritis patients had higher 30-day complication (4.4% vs 1.9%; P < .01) and reoperation rates (1.6% vs 0.93%; P < .01). Frail osteonecrosis patients had higher 30-day complication rates (5.3% vs 2.6%; P < .01). Frail hip fracture patients had higher 30-day complication (6.6% vs 3.8%; P < .01) and reoperation rates (2.9% vs 1.8%; P < .01).

CONCLUSION

Frailty is associated with increased healthcare burden and postoperative events after primary THA. Further research can identify high-risk patients and mitigate complications and costs.

Use of Cementless Metaphyseal Fixation in Revision Total Knee Arthroplasty in the United States

BACKGROUND

Fixation options for revision total knee arthroplasty (rTKA) have expanded and now include cementless metaphyseal fixation. The utilization rates of these implants in the United States are not well known. The purpose of this study was to analyze trends in cementless metaphyseal fixation for rTKA within the American Joint Replacement Registry (AJRR).

METHODS

The AJRR was queried for the years 2015-2019 to identify all rTKA with implant data. Trends in the use of cementless sleeves, metaphyseal cones, and any cementless metaphyseal fixation (sleeves + cones) were examined over the study period using logistic regression analysis.

RESULTS

Twenty thousand two hundred and eighty rTKA were analyzed. Cementless metaphyseal fixation was used in 16% of rTKA and significantly increased over the study period (14% to 19%, P < .0001). Cementless metaphyseal fixation was more frequently utilized during revision for aseptic loosening than other diagnoses (OR 1.014, 95% CI 1.001-1.027). Cementless sleeve utilization decreased over time (11% to 9%, P = .004), driven by decreased use on the femur (4% to 2%, P < .0001). The use of cones increased significantly over time (3% to 9%, P < .0001), driven by increased use on the tibia (2% to 9%, P < .0001). Cones were 22 times more likely to be utilized on the tibia relative to the femur (P < .0001) and were more likely to be used in revisions for infection (OR 1.103, 95% CI 1.089-1.117) and aseptic loosening (OR 1.764, 95% CI 1.728-1.800).

CONCLUSION

Cementless metaphyseal fixation has grown in popularity yet, still comprised only 16% of rTKA over a 5-year period. Most of the increase was due to the utilization of tibial metaphyseal cones.

Total Femur Antibiotic Spacers: Effective Salvage for Complex Periprosthetic Joint Infections

BACKGROUND

A simultaneous periprosthetic joint infection (PJI) of an ipsilateral hip and knee arthroplasty is a challenging complication of lower extremity reconstructive surgery. We evaluated the use of total femur antibiotic-impregnated polymethylmethacrylate (PMMA) bone cement spacers in the staged treatment of such limb-threatening PJIs.

METHODS

Thirteen patients were treated with a total femur antibiotic spacer. The mean age at the time of spacer placement was 65 years. Nine patients had polymicrobial PJIs. All spacers incorporated vancomycin (3.0 g/40 g PMMA) and gentamicin (3.6 g/40 g PMMA), while 8 also included amphotericin (150 mg/40 g PMMA). Eleven spacers were biarticular. Twelve spacers were implanted through one longitudinal incision, while 8 of 12 reimplantations occurred through 2 smaller, separate hip and knee incisions. Mean follow-up after reimplantation was 3 years.

RESULTS

Twelve (92%) patients underwent reimplantation of a total femur prosthesis at a mean of 26 weeks. One patient died of medical complications 41 days after spacer placement. At latest follow-up, 3 patients had experienced PJI recurrence managed with irrigation and debridement. One required acetabular component revision for instability. All 12 reimplanted patients retained the total femur prosthesis with no amputations. Eleven (91%) were ambulatory, and 7 (58%) remained on suppressive antibiotics.

CONCLUSION

Total femur antibiotic spacers are a viable, but technically demanding, limb-salvage option for complex PJIs involving the ipsilateral hip and knee. In the largest series to date, there were no amputations and 75% of reimplanted patients remained infection-free. Radical debridement, antimicrobial diversity, prolonged spacer retention, and limiting recurrent soft tissue violation are potential tenets of success.

LEVEL OF EVIDENCE

IV.

Isolated tibial insert exchange in revision total knee arthroplasty : reliable and durable for wear; less so for instability, insert fracture/dissociation, or stiffness

AIMS

This study aimed to determine outcomes of isolated tibial insert exchange (ITIE) during revision total knee arthroplasty (TKA).

METHODS

From 1985 to 2016, 270 ITIEs were performed at one institution for instability (55%, n = 148), polyethylene wear (39%, n = 105), insert fracture/dissociation (5%, n = 14), or stiffness (1%, n = 3). Patients with component loosening, implant malposition, infection, and extensor mechanism problems were excluded.

RESULTS

Survivorship free of any re-revision was 68% at ten years. For the indication of insert wear, survivorship free of any re-revision at ten years was 74%. Re-revisions were more frequent for index diagnoses other than wear (hazard ratio (HR) 1.9; p = 0.013), with ten-year survivorships of 69% for instability and 37% for insert fracture/dissociation. Following ITIE for wear, the most common reason for re-revision was aseptic loosening (33%, n = 7). For other indications, the most common reason for re-revision was recurrence of the original diagnosis. Mean Knee Society Scores improved from 54 (0 to 94) preoperatively to 77 (38 to 94) at ten years.

CONCLUSION

After ITIE, the risk and reasons for re-revision correlated with preoperative indications. The best results were for polyethylene wear. For other diagnoses, the re-revision rate was higher and the failure mode was most commonly recurrence of the original indication for the revision TKA. Cite this article: Bone Joint J 2021;103-B(6):1103-1110.

Direct Anterior Approach Total Hip Arthroplasty Is Not Associated with Increased Infection Rates: A Systematic Review and Meta-Analysis

BACKGROUND

The direct anterior approach (DAA) for primary total hip arthroplasty (THA) has recently increased in popularity. Recent evidence has raised concerns about whether use of the DAA is associated with increased rates of superficial and deep infection. The aim of this study was to systematically assess the literature and comparatively evaluate the rate of superficial and deep infection following primary THA using the DAA and non-direct anterior (non-DAA) approaches.

METHODS

This study was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) statement. Primary outcome measures evaluated were rates of superficial and deep infection in patients undergoing DAA and non-DAA primary THA.

RESULTS

A total of 1,872 studies were identified in the original search, of which 15 studies satisfied inclusion criteria. Our analysis evaluated 120,910 primary THAs, including 14,908 DAA and 106,002 non-DAA. The rate of superficial infection was 1.08% for DAA compared with 1.24% for non-DAA (odds ratio [OR] = 1.01, 95% confidence interval [CI] = 0.79 to 1.30, p = 0.921). The rate of deep infection was 0.73% for DAA compared with 0.51% for non-DAA (OR = 1.03, 95% CI = 0.80 to 1.32, p = 0.831).

CONCLUSIONS

This study found no difference in the rate of superficial or deep infection after primary THA using the DAA versus other surgical approaches. Our results suggest that comparative infection risk need not be a primary driver in the choice of surgical approach.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Intermediate to Long-Term Follow-up of Cementing Liners into Well-Fixed Acetabular Components

BACKGROUND

The cementation of a new liner into a well-fixed acetabular component is common during revision total hip arthroplasty (THA) for many indications, but most commonly for lack of a modern, compatible, highly cross-linked polyethylene (HXLPE) liner. However, little is known about the intermediate-term to long-term durability of this strategy. The purpose of this study was to evaluate the implant survivorship, risk of complications, clinical outcomes, and radiographic results of cementing a new HXLPE liner into a well-fixed acetabular component.

METHODS

We retrospectively identified 323 revision THAs in which a nonconstrained HXLPE liner was cemented into a well-fixed acetabular component. The mean age at the time of the revision THA was 63 years, and 50% of patients were female. The most common indications for revision THA were polyethylene wear and osteolysis (48%), aseptic femoral loosening (35%), and hip instability (8%). The mean follow-up was 9 years.

RESULTS

Polyethylene liner failure occurred in 11 cases (3%). In all cases, the cemented liner dissociated from the acetabular component. At 10 years, the survivorship free from any revision was 80% (95% confidence interval [CI], 75% to 84%) and the survivorship free from any reoperation was 77% (95% CI, 72% to 82%). The most common reason for re-revision was dislocation (45% of reoperations). A dislocation occurred in 17% of cases. Hips that underwent revision for instability were significantly more likely to dislocate compared with hips that underwent revision for liner wear (hazard ratio [HR], 2.3 [95% CI, 1.2 to 4.5]; p = 0.02). Elevated rim or face-changing liners were significantly more likely to dissociate than flat liners (HR, 9.0 [95% CI, 1.2 to 70.6]; p = 0.04).

CONCLUSIONS

Cementation of a nonconstrained HXLPE liner into a well-fixed acetabular component during revision THA provided durable fixation with only a small number of failures at the cement interface (3%). Instability after this procedure remains a concern, but this is multifactorial in nature. These data support the continued use of this technique, when necessary, during revision THA.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Excellent two-year survivorship of 3D-printed metaphyseal cones in revision total knee arthroplasty

AIMS

Metaphyseal fixation during revision total knee arthroplasty (TKA) is important, but potentially difficult when using historical designs of cone. Material and manufacturing innovations have improved the size and shape of the cones which are available, and simplified the required bone preparation. In a large series, we assessed the implant survivorship, radiological results, and clinical outcomes of new porous 3D-printed titanium metaphyseal cones featuring a reamer-based system.

METHODS

We reviewed 142 revision TKAs in 139 patients using 202 cones (134 tibial, 68 femoral) which were undertaken between 2015 and 2016. A total of 60 involved tibial and femoral cones. Most cones (149 of 202; 74%) were used for Type 2B or 3 bone loss. The mean age of the patients was 66 years (44 to 88), and 76 (55 %) were female. The mean body mass index (BMI) was 34 kg/m² (18 to 60). The patients had a mean of 2.4 (1 to 8) previous operations on the knee, and 68 (48%) had a history of prosthetic infection. The mean follow-up was 2.4 years (2 to 3.6).

RESULTS

Survivorship free of cone revision for aseptic loosening was 100% and survivorship free of any cone revision was 98%. Survivorships free of any revision and any reoperation were 90% and 83%, respectively. Five cones were revised: three for infection, one for periprosthetic fracture, and one for aseptic tibial loosening. Radiologically, three unrevised femoral cones appeared loose in the presence of hinged implants, while the remaining cones appeared stable. All cases of cone loosening occurred in patients with Type 2B or 3 defects. The mean Knee Society score (KSS) improved significantly from 50 (0 to 94) preoperatively to 87 (72 to 94) (p < 0.001). Three intraoperative fractures with cone impaction (two femoral, one tibial) healed uneventfully.

CONCLUSION

Novel 3D-printed titanium cones, with a reamer-based system, yielded excellent early survivorship and few complications in patients with severe bone loss undergoing difficult revision TKA. The diversity of cone options, relative ease of preparation, and outcomes rivalling those of previous designs of cone support their continued use. Cite this article: Bone Joint J 2020;102-B(6 Supple A):107-115.

Are Postoperative Hip Precautions Necessary After Primary Total Hip Arthroplasty Using a Posterior Approach? Preliminary Results of a Prospective Randomized Trial

BACKGROUND

It is unclear whether posterior hip precautions after primary total hip arthroplasty (THA) reduce the incidence of early postoperative dislocation.

METHODS

We performed a prospective randomized study to evaluate the effect of hip precautions on incidence of early dislocation after primary THA using a posterior approach. Between January 2016 and April 2019, 587 patients (594 hips) were consented and randomized into restricted or unrestricted groups. No significant demographic or surgical differences existed between groups. The restricted group was instructed to refrain from hip flexion >90°, adduction across midline, and internal rotation for 6 weeks. 98.5% (585 of 594) of hips were available for minimum 6-week follow-up (291 restricted and 294 unrestricted). Power analysis showed that 579 hips per group are needed to demonstrate an increase in dislocation rate from 0.5% to 2.5% with 80% power.

RESULTS

At average follow-up of 15 weeks (range, 6-88), there were 5 dislocations (incidence, 0.85%). Three posterior dislocations occurred in the restricted group at a mean of 32 days (range, 17-47), and 2 posterior dislocations occurred in the unrestricted group at a mean of 112 days (range, 21-203), with no difference in dislocation rate between groups (1.03% vs 0.68%; odds ratio, 0.658; 95% confidence interval, 0.11-3.96; P = .647). At 6 weeks, unrestricted patients endorsed less difficulty with activities of daily living, earlier return to driving, and more time spent side sleeping (P < .05).

CONCLUSION

Preliminary analysis suggests that removal of hip precautions after primary THA using a posterior approach was not associated with early dislocation and facilitated return to daily functions. Investigation to appropriate power is warranted.

Is There a Benefit to Modularity for Femoral Revisions When Using a Splined, Tapered Titanium Stem?

BACKGROUND

Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs monoblock splined, tapered titanium stems in revision THA.

METHODS

We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2-17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included.

RESULTS

There were no statistically significant differences in rates of reoperation (22.3% vs 17.9%; P = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .20) between groups.

CONCLUSION

Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine whether modularity is beneficial for more complex femoral defects.

Inpatient Versus Outpatient Arthroplasty: A Single-Surgeon, Matched Cohort Analysis of 90-Day Complications

BACKGROUND

Although some prior work supports the safety of same-day arthroplasty performed in a hospital, concerns remain when these procedures are performed in a free-standing ambulatory surgery center. The purpose of this study is to compare 90-day complication rates between matched cohorts that underwent inpatient vs outpatient arthroplasty at an ambulatory surgery center.

METHODS

A single-surgeon cohort of 243 consecutive patients who underwent outpatient arthroplasty was matched with 243 inpatients who had the same procedure. One-to-one nearest-neighbor matching with respect to gender, age, American Society of Anesthesiologists Score, and body mass index was utilized. The 486 primary arthroplasties included 178 unicondylar knees (36.6%), 146 total hips (30.0%), 92 total knees (18.9%), and 70 hip resurfacings (14.5%). Ninety-day outcomes including reoperation, readmission, unplanned clinic or emergency department visits, and major and minor complications were compared using a 2-sample proportions test.

RESULTS

The 2 cohorts were similar in distribution of demographic variables, demonstrating successful matching. The inpatient and outpatient cohorts both had readmission rates of 2.1% (P = 1.0). With the number of subjects studied, there were no statistically significant differences in rates of major complications (2.1% vs 2.5%, P = 1.0), minor complications (7.0% vs 7.8%, P = .86), reoperations (0.4% vs 2.1%, P = .22), emergency department visits (1.6% vs 2.5%, P = .52), or unplanned clinic visits (3.3% vs 5.8%, P = .19).

CONCLUSION

This study suggests that arthroplasty procedures can be performed safely in an ambulatory surgery center among appropriately selected patients without an increased risk of complications.

Short-term Complications After Revision Hip Arthroplasty for Prosthetic Joint Infection Are Increased Relative to Noninfectious Revisions

BACKGROUND

Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) is associated with significant morbidity and cost. The purpose of this study was to determine how rates of perioperative complications, operative duration, and postoperative length of stay (LOS) in patients undergoing revision THA for PJI compare to primary THA and to revision THA for non-PJI.

METHODS

We used the National Surgical Quality Improvement Program registry from 2005 to 2015 to identify all patients who underwent primary and revision THA. Patients were placed into cohorts based on the surgical procedure and by indication, including (1) primary THA, (2) revision THA for PJI, and (3) revision THA for non-PJI. Differences in 30-day postoperative medical complications, hospital readmissions, operative duration, and LOS were compared using bivariate and multivariate analyses.

RESULTS

One lakh fourteen thousand five hundred five THA patients were identified, with 102,460 (89.5%) patients undergoing a primary THA and 12,045 (10.5%) undergoing a revision procedure. Of the 12,045 revision procedures, 10,777 (89.5%) were for non-PJI indications and 1268 (10.5%) were for PJI. Relative to primary THA, patients undergoing revision THA for PJI had an increased rate of total complications (odds ratio [OR] 3.96), sepsis (OR 13.15), deep surgical site infections (SSIs, OR 8.58), superficial SSI (OR 2.14, P = .002), nonhome discharge (OR 1.85), readmissions (OR 2.46), LOS (+3.0 days), and operative duration (+61 minutes). Compared with non-PJI revisions, PJI revisions had an increased rate of total complications (OR 2.42), sepsis (OR 5.51), deep SSI (OR 2.12), nonhome discharge (OR 1.47), and LOS (+1.8 days).

CONCLUSION

Revision THA for PJI is associated with increased postoperative complications, nonhome discharge, and LOS relative to non-PJI revision THA. Separate care pathways and reimbursement bundles should be considered for patients with PJI.

LEVEL OF EVIDENCE

III.

Adverse Local Tissue Reaction After a Metal-on-Metal Total Hip Prosthesis Without Elevated Serum Metal Ion Levels

In the 1990s, metal-on-metal (MoM) bearings were reintroduced in total hip arthroplasty (THA), having the proposed advantages of decreased wear and improved stability. However, catastrophic adverse local tissue reaction (ALTR) secondary to metal debris from both the bearing surface and the head-neck junction is a well-recognized complication. The measurement of metal ion levels in the serum is often a first-line test to identify failure of a MoM bearing. The authors describe a 70-year-old man who presented with a multiply revised MoM THA and a large periprosthetic fluid collection incidentally seen during computed tomography for renal nephrolithiasis. The patient reported painless, progressive swelling over the lateral aspect of the hip. An infectious workup including serum erythrocyte sedimentation rate, C-reactive protein, and intraarticular hip aspiration yielded negative results. Metal ion levels in the serum, including a minimally elevated cobalt level, were unremarkable, and metal-lymphocyte transformation testing yielded negative results. Radiographic imaging revealed progressive osteolysis around the proximal femur, and magnetic resonance imaging showed large fluid collections with irregular wall thickening surrounding the gluteal and iliopsoas musculature. At revision surgery, a large fluid collection and corrosion at the head-neck junction were present. Pathology specimens confirmed the presence of an ALTR. This report presents a previously undescribed case of an ALTR secondary to MoM THA in the absence of elevated serum metal ion levels. This indicates the necessity of considering all aspects of a patient's clinical presentation, imaging modalities, and laboratory testing in the evaluation and diagnosis of a symptomatic MoM THA. [Orthopedics. 2018; 41(3):e438-e441.].

Same-Day Discharge Compared with Inpatient Hospitalization Following Hip and Knee Arthroplasty

BACKGROUND

Discharge from the hospital on the day of (same-day) hip and knee arthroplasties has become more common; however, to our knowledge, few studies have compared morbidity between same-day and inpatient surgical procedures. The aims of this study were to compare matched cohorts of patients who underwent same-day and inpatient hip or knee arthroplasty in terms of postoperative complications and 30-day readmission rates.

METHODS

Patients who underwent primary elective total hip arthroplasty, total knee arthroplasty, or unicompartmental knee arthroplasty from 2005 to 2014 were identified from the National Surgical Quality Improvement Program registry. Patients discharged the day of the surgical procedure were matched 1:1 with patients who had an inpatient stay using propensity scores. The rates of 30-day adverse events and readmission were compared between matched cohorts using the McNemar test. Risk factors for 30-day readmission following same-day procedures were identified using multivariate regression.

RESULTS

Of 177,818 patients identified, 1,236 (0.70%) underwent a same-day surgical procedure. After matching, there were no differences in overall adverse events or readmission between same-day and inpatient groups, although inpatients had increased thromboembolic events (p = 0.048) and same-day patients had an increased rate of return to the operating room (p = 0.016). When procedures were assessed individually, the only difference identified was that the same-day total knee arthroplasty cohort had an increased return to the operating room compared with the inpatient total knee arthroplasty cohort (p = 0.046). Body mass index of ≥35 kg/m (p = 0.035), insulin-dependent diabetes (p = 0.041), non-insulin-dependent diabetes (p = 0.013), and age of ≥85 years (p = 0.039) were associated with 30-day readmission following same-day surgical procedures. Infection was the most common reason for reoperation and readmission following same-day procedures.

CONCLUSIONS

No significant differences in overall postoperative complications or readmission were found between matched cohorts of patients who underwent same-day and inpatient hip and knee arthroplasties, although inpatients had a higher rate of thromboembolic events and same-day patients had a higher rate of reoperation. Patients with a body mass index of ≥35 kg/m, diabetes, and an age of ≥85 years had an increased risk of 30-day readmission following same-day procedures, which was most commonly due to infection.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

A classification-based approach to the patella in revision total knee arthroplasty

Background

There is a paucity of data to guide management of the patella in revision total knee arthroplasty (RTKA). The purpose of this study was to review our experience with patellar management in RTKA.

Methods

We retrospectively reviewed 422 consecutive RTKAs at a minimum of 2 years (mean, 42 months). Patellar management was guided by a classification that considered stability, size, and position of the implanted patellar component, thickness/quality of remaining bone stock, and extensor mechanism competence.

Results

Management in 304 aseptic revisions included retention of a well-fixed component in 212 (69.7%) and revision using an all-polyethylene component in 46 (15.1%). Patella-related complications included 5 extensor mechanism ruptures (1.6%), 3 cases of patellar maltracking (1.0%), and 2 periprosthetic patellar fractures (0.7%). Of 118 2-stage revisions for infection, an all-polyethylene component was used in 88 (74.6%), patelloplasty in 20 (16.9%), and patellectomy in 7 (5.9%). Patella-related complications included 4 cases of patellar maltracking (3.4%), 3 extensor mechanism ruptures (2.5%), and 1 periprosthetic patellar fracture (0.8%).

Conclusions

Septic revisions required concomitant lateral releases more frequently (38.1% vs 10.9%; P < .02) but had a similar rate of patellar complications (6.8% vs 3.3%; P = .40). No cases required rerevision specifically for failure of the patellar component. Patients who had a patelloplasty had worse postoperative Knee Society functional scores than those with a retained or revised patellar component. In most aseptic RTKAs, a well-fixed patellar component can be retained. If revision is required, a standard polyethylene component is sufficient in most septic and aseptic revisions. Rerevisions related to the patellar component are infrequent.

A Prospective Randomized Trial of Mini-Incision Posterior and 2-Incision Total Hip Arthroplasty: Minimum 5-Year Follow-Up

BACKGROUND

We previously described the results of a randomized controlled trial of mini-posterior vs 2-incision total hip arthroplasty and were unable to demonstrate significant differences in early outcomes. As less-invasive anterior approaches remain popular, the purpose of this report was to re-examine the outcomes at a minimum 5-year follow-up.

METHODS

Seventy-two patients undergoing primary total hip arthroplasty were randomized to a mini-posterior or 2-incision approach. Complications, revisions, and clinical outcome measures were compared. Radiographs were reviewed for implant loosening. A power analysis using a minimal clinically important difference value of 6 points for the Harris hip score revealed 28 patients required per group.

RESULTS

At a mean of 8.2 years (range, 5-10 years), 6 patients died without revision surgery and 63 of 66 living patients were reviewed. There were 6 total failures, 3 in each group. For unrevised patients, there were no significant differences between groups (posterior vs 2-incision) in the Harris hip score (95.5 ± 3.5 vs 95.7 ± 6.3; P = .88), 12-item Short Form Survey physical composite score (50.5 ± 8.5 vs 49.0 ± 9.1; P = .53), 12-item Short Form Survey mental composite score (57.3 ± 4.1 vs 55.4 ± 8.0; P = .25), or single assessment numeric evaluation score (97.1 ± 3.7 vs 97.8 ± 5.2; P = .55).

CONCLUSION

We found no differences in midterm outcomes between the 2 approaches. Given the increased complexity, operative time, and need for fluoroscopy with the 2-incision approach combined with equivalent early and midterm outcomes, the 2-incision approach has been abandoned in the senior author's practice.

Medial Gastrocnemius Flap in the Course of Treatment for an Infection at the Site of a Total Knee Arthroplasty

Introduction

The pedicled medial gastrocnemius flap provides a robust coverage option for most soft-tissue deficiencies over the distal anterior aspect of the knee encountered in the setting of an infection after total knee arthroplasty.

Indications & Contraindications

Step 1 Patient Positioning

Position the patient supine with an ipsilateral sterile thigh tourniquet to allow room for harvest of a split-thickness skin graft as needed.

Step 2 Revision Arthroplasty for Infection

Perform the arthroplasty to address the underlying deep infection (e.g., irrigation and debridement with exchange of modular components, component removal with antibiotic spacer placement, antibiotic spacer exchange, or second-stage reimplantation) prior to the medial gastrocnemius flap that is utilized for soft-tissue coverage.

Step 3 Incision and Approach for the Medial Gastrocnemius Flap

Use one of two different surgical approaches for the exposure and elevation of the medial gastrocnemius muscle and the identification of its vascular pedicle: the medial approach or the posterior midline approach.

Step 4 Elevation of the Medial Gastrocnemius Flap

Protect the sural artery pedicle in the popliteal fossa because it is key to raising a viable medial gastrocnemius flap.

Step 5 Transposition and Insetting of the Flap Over the Defect

Rotate the flap and transpose it anteriorly over the defect either through a subcutaneous tunnel or by dividing the intervening skin bridge.

Step 6 Closure Skin-Grafting and Dressing Application

Complete the layered skin closure and place a split-thickness skin graft over the remaining exposed muscle flap and a nonadherent compressive bolster dressing or negative-pressure device over the skin graft to prevent hematoma under the skin graft.

Step 7 Postoperative Care

Progress range of motion of the knee once the flap and graft show evidence of survival, while an appropriate antibiotic regimen is completed.

Results

We recently reported the largest English-language series, to our knowledge, of medial gastrocnemius flaps performed for soft-tissue coverage in the course of treatment for infection after total knee arthroplasty¹³.

Pitfalls & Challenges

A cost comparison of unicompartmental and total knee arthroplasty

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty (TKA) in appropriately selected patients. There is a paucity of data comparing hospital resource utilization and costs for UKA versus TKA.

METHODS

We retrospectively reviewed 128 patients who underwent UKA or TKA for osteoarthritis by a single surgeon in the 2011 Fiscal Year. Sixty-four patients in each group were matched based on sex, age, race, body mass index, Charlson Comorbidity Index, and insurance type. Clinical data were obtained from medical records while costs were obtained from hospital billing. Bivariate analyses were used to compare outcomes.

RESULTS

Both anesthesia and operative time (minutes) were significantly shorter for patients undergoing UKA (125.7 vs. 156.4; p<0.001, and 81.4 vs. 112.2; p<0.001). UKA patients required fewer transfusions (0% vs. 11.0%; p=0.007) and had a shorter hospital stay (2.2 vs. 3.8days; p<0.001). 96% of UKAs were discharged home compared with 75% of TKAs (p<0.001). Hospital direct costs were lower for UKA ($7893 vs. $11,156; p<0.001) as were total costs (hospital direct costs plus overhead; $11,397 vs. $16,243; p<0.001). Supply costs and implant costs were similarly lower for UKA ($701 vs. $781; p<0.001, and $3448 vs. $5006; p<0.001).

CONCLUSION

Our data suggest that UKA provides a cost-effective alternative to TKA in appropriately selected patients. As the number of patients with end-stage arthritis of the knee requiring surgical care continues to rise, the costs of caring for these patients must be considered.

LEVEL OF EVIDENCE

Level III, case control study.

Is There a Benefit to Modularity in 'Simpler' Femoral Revisions?

BACKGROUND

Modular revision femoral components allow the surgeon to make more precise intraoperative adjustments in anteversion and sizing, which may afford lower dislocation rates and improved osseointegration, but may not offer distinct advantages when compared with less expensive monoblock revision stems.

QUESTIONS/PURPOSES

We compared modular and monoblock femoral components for revision of Paprosky Type I to IIIA femoral defects to determine (1) survivorship of the stems; and (2) complications denoted as intraoperative fracture, dislocation, or failure of osseointegration.

METHODS

Between 2004 and 2010, participating surgeons at three centers revised 416 total hip arthroplasties (THAs) with Paprosky Type I to IIIA femoral defects. Of those with minimum 2-year followup (343 THAs, mean followup 51 ± 13 months), 150 (44%) were treated with modular stems and 193 (56%) were treated with monoblock, cylindrical, fully porous-coated stems. During this time, modular stems were generally chosen when there was remodeling of the proximal femur into retroversion and/or larger canal diameters (usually > 18 mm). A total of 27 patients died (6%) with stems intact before 2 years, 46 THAs (13%) were lost to followup before 2 years for reasons other than death, and there was no differential loss to followup between the study groups. The modular stems included 101 with a cylindrical distal geometry (67%) and 49 with a tapered geometry (33%). Mean age (64 versus 68 years), percentage of women (53% versus 47%), and body mass index (31 versus 30 kg/m(2)) were not different between the two cohorts, whereas there was trend toward a slightly greater case complexity in the modular group (55% versus 65% Type 3a femoral defects, p = 0.06). Kaplan-Meier survivorship was calculated for the endpoint of aseptic revision. Proportions of complications in each cohort (dislocation, intraoperative fracture, and failure of osseointegration) were compared.

RESULTS

Femoral component rerevision for any reason (including infection) was greater (OR, 2.01; 95% CI, 1.63-2.57; p = 0.03) in the monoblock group (27 of 193 [14%]) compared with the modular cohort (10 of 150 [7%]). Femoral component survival free from aseptic rerevision was greater in the modular group with 91% survival (95% CI, 89%-95%) at 9 years compared with 86% survival (95% CI, 83%-88%) for the monoblock group in the same timeframe. There was no difference in the proportion of mechanically relevant aseptic complications (30 of 193 [16%] in the monoblock group versus 34 of 150 [23%] in the modular group, p = 0.10; OR, 1.47; 95% CI, 0.86-2.53). There were more intraoperative fractures in the modular group (17 of 150 [11%] versus nine of 193 [5%]; OR, 2.2; 95% CI, 1.68-2.73; p = 0.02). There were no differences in the proportions of dislocation (13 of 193 [7%] monoblock versus 14 of 150 [9%] modular; OR, 0.96; 95% CI, 0.67-1.16; p = 0.48) or failure of osseointegration (eight of 193 [4%] monoblock versus three of 150 [2%] modular; OR, 1.92; 95% CI, 0.88-2.84; p = 0.19) between the two groups with the number of hips available for study.

CONCLUSIONS

Although rerevisions were less common in patients treated with modular stems, aseptic complications such as intraoperative fractures were more common in that group, and the sample was too small to evaluate corrosion-related or fatigue concerns associated with modularity. We cannot therefore conclude from this that one design is superior to the other. Larger studies and pooled analyses will need to be performed to answer this question, but we believe modularity should be avoided in more straightforward cases if possible.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Perceived Leg-Length Discrepancy After Primary Total Knee Arthroplasty: Does Knee Alignment Play a Role?

Leg length discrepancy (LLD) is common after total knee arthroplasty (TKA) although its incidence has not been well documented. The purpose of this study was to determine the incidence of perceived LLD before and after primary total knee arthroplasty as well as to determine the correlation between mechanical axis of the knee and perceived LLD. The incidence and time frame of resolution of postoperative LLD was also assessed. Seventy-three patients were prospectively enrolled. Evaluation included patient surveys regarding perceived LLD preoperatively, and at 3- to 6-week, 3-month, 6-month, and 1-year visits. Mechanical axis radiographs were obtained and the relationship of mechanical axis in patients with and without perceived LLD, both before and after surgery, was determined. Analysis was also performed for separate varus and valgus deformities. The effect of surgery on patients' perception of LLD was also determined. Fifty-three patients did not perceive a LLD preoperatively and 18 perceived a LLD preoperatively. Sixty-four patients did not perceive a LLD postoperatively and 7 patients perceived a LLD postoperatively. There was a significant difference in patients who perceived LLD preoperatively and those who perceived LLD postoperatively (P = .035). Of the 7 patients with a perceived LLD postoperatively, all noted resolution of LLD at a mean of 8.5 weeks. There were no statistically significant correlations of knee alignment to perceived LLD in any patient groups. Body mass index and age did not demonstrate any statistical differences between patient groups. Perceived LLD is common in patients undergoing TKA; however, perceived LLD decreases after surgery. Although approximately 10% of patients perceive a LLD after surgery, the vast majority resolve within 3 months. Our study did not show any relationship between mechanical knee alignment and perception of LLD.

Synovial chemokine expression and relationship with knee symptoms in patients with meniscal tears

OBJECTIVE

In patients with knee OA, synovitis is associated with knee pain and symptoms. We previously identified synovial mRNA expression of a set of chemokines (CCL19, IL-8, CCL5, XCL-1, CCR7) associated with synovitis in patients with meniscal tears but without radiographic OA. CCL19 and CCR7 were also associated with knee symptoms. This study sought to validate expression of these chemokines and association with knee symptoms in more typical patients presenting for meniscal arthroscopy, many who have pre-existing OA.

DESIGN

Synovial fluid (SF) and biopsies were collected from patients undergoing meniscal arthroscopy. Synovial mRNA expression was measured using quantitative RT-PCR. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was administered preoperatively. Regression analyses determined if associations between chemokine mRNA levels and KOOS scores were independent of other factors including radiographic OA. CCL19 in SF was measured by ELISA, and compared to patients with advanced knee OA and asymptomatic organ donors.

RESULTS

90% of patients had intra-operative evidence of early cartilage degeneration. CCL19, IL-8, CCL5, XCL1, CCR7 transcripts were detected in all patients. Synovial CCL19 mRNA levels independently correlated with KOOS Activities of Daily Living (ADL) scores (95% CI [-8.071, -0.331], P = 0.036), indicating higher expression was associated with more knee-related dysfunction. SF CCL19 was detected in 7 of 10 patients, compared to 4 of 10 asymptomatic donors.

CONCLUSION

In typical patients presenting for meniscal arthroscopy, synovial CCL19 mRNA expression was associated with knee-related difficulty with ADL, independent of other factors including presence of radiographic knee OA.

Increased incidence of patella baja after total knee arthroplasty revision for infection

The incidence of patella baja in total knee arthroplasty (TKA) revisions for aseptic and septic causes is not well defined. We retrospectively reviewed 101 mobile-bearing TKA revisions performed between 2003 and 2009. Aseptic (n=67) and septic (n=34) revisions were compared for patella baja. A nonarticulating spacer was used as the initial treatment for infected cases. The Insall-Salvati ratio was radiographically measured before surgery (preexplant for septic revisions) and at latest follow-up (postreplant for septic revisions). Mean (SD) Insall-Salvati ratio did not differ between groups before surgery, 1.00 (0.25) for aseptic and 0.96 (0.22) for septic, but differed significantly after surgery, 0.99 (0.23) for aseptic and 0.77 (0.24) for septic. After correcting for preoperative patellar height, there was a statistically significant postoperative difference between aseptic cases, 1.09 (0.19), and septic cases, 0.82 (0.21). There was also a significant difference in mean (SD) postoperative range of motion (ROM) between aseptic cases, 108.0° (20.7°), and septic cases, 92.2° (34.6°), and decreased ROM between cases with patella baja, 95.1° (31.6°) and cases without patella baja, 106.8° (23.6°). TKA revisions done for septic causes using a nonarticulating spacer resulted in a higher incidence of patella baja and decreased ROM.

Are short fully coated stems adequate for "simple" femoral revisions?

BACKGROUND

Many studies suggest long femoral components should be used in revision THA. However, longer stems are more difficult to insert and reduce femoral bone stock for future revisions.

QUESTIONS/PURPOSES

We investigated (1) how frequently a short (≤ 160-mm or primary-length) fully porous-coated stem could be utilized for Paprosky Type I to IIIA femoral defects, (2) how often the tip of the old stem or cement mantle was bypassed by the revision implant, (3) Harris hip scores, radiographic signs of osseointegration, and revision frequency, and (4) complications associated with these reconstructions.

METHODS

Two surgeons performed 277 femoral revisions graded as Paprosky Types I to IIIA between 2004 and 2009. When femoral canal diameter was less than 18 mm, these surgeons generally used the shortest stem capable of achieving a minimum of 4 cm of scratch fit in the femoral isthmus. Patients were evaluated clinically using the Harris hip score and radiographically for component loosening and to determine whether the revision component bypassed the prior stem tip or cement mantle.

RESULTS

A short stem was utilized in 144 of the 277 revisions (52%). In 113 (78%), the revision femoral component did not bypass the tip of the prior stem or cement mantle. The Harris hip score improved (p < 0.001) from 36 preoperatively to 76 at a mean of 4 years (range, 2-8 years). Twelve stems required repeat revision including six (4.9%) for failed ingrowth. Complications included four intraoperative fractures, three postoperative femoral fractures, one cortical perforation, and eight dislocations.

CONCLUSIONS

Primary-length extensively coated stems provided reliable fixation for ½ of our Paprosky Type I to IIIA femoral revisions. When considering the use of such a component, the revision surgeon should take into account a small risk of failed osseointegration and technical challenges associated with this technique.

The Chitranjan Ranawat Award: Should prophylactic antibiotics be withheld before revision surgery to obtain appropriate cultures?

BACKGROUND

Preoperative antibiotics are known to be critical for decreasing the risk of periprosthetic joint infection (PJI) in primary THA and TKA. However, antibiotics often are withheld before revision surgery, as there is concern that even a single dose of prophylactic antibiotics may affect intraoperative cultures.

QUESTIONS/PURPOSES

In this prospective randomized controlled trial, we determined the effect of a single dose of prophylactic antibiotics on cultures obtained at the time of revision arthroplasty.

METHODS

We randomized 65 patients with known PJI after 37 TKAs and 28 THAs at three centers. Patients were included in the trial if they had a culture-positive aspiration and had not taken antibiotics within 2 weeks of the procedure. Patients were randomized to receive prophylactic antibiotics either before the skin incision or after a minimum of three sets of intraoperative cultures were obtained. Preoperative and intraoperative cultures were then compared. Results between patients who did and did not receive antibiotics were compared using an equivalence test for proportion differences (two one-sided t-tests [TOST]) with a 0.2 margin.

RESULTS

Intraoperative cultures yielded the same organisms as preoperative cultures in 28 of 34 patients (82%) randomized to receive antibiotics before the skin incision compared to 25 of 31 patients (81%) randomized to receive antibiotics after obtaining operative cultures (statistically equivalent by TOST estimate: p = 0.0290).

CONCLUSIONS

In this randomized controlled trial, there was no effect on the results of cultures obtained intraoperatively when prophylactic antibiotics were administered before skin incision. Given the known benefits of prophylactic antibiotics in preventing PJI, preoperative prophylaxis should not be withheld in revision surgery for fear of affecting cultures.

Recurrent periprosthetic joint infection: persistent or new infection?

It is unclear if recurrent periprosthetic joint infection (PJI) is a result of failed pathogen eradication. This study addresses this issue. We identified 92 patients from three institutions who failed two-stage exchange. Cultured organisms at each stage of treatment were compared to determine whether these were persistent or new infections. Only twenty-nine of the 92 patients (31.5%) had identical organisms at treatment failure. Of the failures associated with Staphylococcus as the original infecting organism, 37% (25 of 67) failed due to the same organism compared to only 16% (four of 25) caused by other organisms. Positive cultures at reimplantation and poor health status were associated with higher rates of recurrent infection due to new organisms. Successful management of PJI with a two-stage exchange must stress minimization of comorbid risk factors that may contribute to the low success rate of PJI treatment and recurrence of infection.

Should draining wounds and sinuses associated with hip and knee arthroplasties be cultured?

We assessed the utility of culturing draining wounds or sinuses in evaluating periprosthetic joint infection (PJI). Fifty-five patients with a draining wound or sinus after total joint arthroplasty (28 knees, 27 hips) who had not received antibiotics for at least two weeks were prospectively studied. Superficial wound cultures were compared to intra-articular cultures to determine accuracy in isolating infecting organism(s). The superficial cultures were concordant with deep cultures in 26 of 55 cases (47.3%) and were more likely to generate polymicrobial results (27.3% vs. 10.9%; P=0.023). In 23 cases (41.8%), the superficial cultures would have led to a change in antibiotic regimen. Superficial cultures yielded bacterial growth in 8 of the 10 cases (80%) when deep cultures and further work-up suggested the absence of deep infection. Given the potential to misguide diagnosis and treatment, we recommend against obtainment of superficial cultures in patients with a draining wound or sinus following hip or knee arthroplasty.

What is the prevalence of MRSA colonization in elective spine cases?

BACKGROUND

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection is increasing. However, the prevalence of MRSA colonization among patients undergoing spine surgery is unclear.

QUESTIONS/PURPOSES

We therefore (1) determined the prevalence of MRSA colonization in a population of patients scheduled for elective spine surgery; and (2) evaluated whether MRSA screening and treatment reduce the rate of early wound complications.

METHODS

We retrospectively reviewed prospectively collected data from 1002 patients undergoing elective spine surgery in 2010. There were 719 primary and 283 revision surgeries. Instrumentation was used in 72.0% cases and autologous iliac crest bone graft was taken in 65.1%. Twelve patients were lost to followup; of the remaining 990 patients, 503 were screened for MRSA and 487 were not. MRSA-colonized patients were treated with mupirocin and chlorhexidine. An early wound complication was defined as wound drainage or the presence of an abscess. Patients were followed for a minimum of 3 months (average, 7 months; range, 3-545 days).

RESULTS

Of the patients undergoing elective spine surgery and screened for MRSA, 14 of 503 (2.8%) were colonized with MRSA. The rates of early wound complications were similar for patients who were screened and pretreated for MRSA (17 of 503 [3.4%]) compared with those who were not (17 of 487 [3.5%]).

CONCLUSIONS

The colonization rate for MRSA in our elective spine surgery population was comparable to that in the arthroplasty literature.

LEVEL OF EVIDENCE

Level III, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.