Alignment in Total Knee Arthroplasty: Avoid Crossing Over from Varus to Valgus

BACKGROUND

Ideal target limb alignment remains a debated topic in total knee arthroplasty (TKA). We aimed to determine the effect of limb alignment correction on patient-reported outcomes and knee range-of-motion (ROM) following TKA.

METHODS

In this retrospective analysis, patients (N = 409) undergoing primary TKA at a single institution were studied. Using full leg-length radiographs, limb alignment was measured pre-and postoperatively. Patients were categorized by pre-operative (Pre-op) alignment (varus > 0°; valgus < 0°). Pre-op varus patients were then divided as follows based on post-operative alignment: neutral (VAR-NEUT, 0°±2); remaining in varus (VAR-rVAR, ≥3°); cross-over to valgus (VAR-CO, ≤-3°). Similarly, Pre-op valgus patients were divided as follows for post-operative alignment: neutral (VAL-NEUT, 0°±2); remaining in valgus (VAL-rVAL, ≤-3°); cross-over to varus (VAL-CO, ≥3°). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS Jr.) survey scores were collected at pre-op as well as at 6-weeks, 3-, 6-, and 12-months post-op. Knee ROM was collected at 2 weeks, 6 to 12 weeks, and > 6-months post-op. An analysis of variance (ANOVA) repeated on time followed by a Bonferroni post-hoc test was used to compare outcomes for the postoperative alignment subgroups.

RESULTS

Pre-op Varus patients: Those in the VAR-CO group (overcorrected to -4.03° ± 1.95valgus) were observed to have lower KOOS Jr. scores at 3-, 6-, and 12-months post-op compared to those in the NEUT group (P < 0.05). This finding was paired with reduced ROM at 6 to 12 weeks post-op in the VAR-CO group compared to VAR-NEUT and VAR-rVAR (P < 0.05). Pre-op Valgus patients: Those in the VAL-rVal group (left in -4.39° ± 1.39valgus) were observed to have reduced knee flexion at 6 to 12 weeks post-op compared to VAL-NEUT and VAL-CO.

CONCLUSION

These findings indicate that post-operative valgus alignment via either crossing over to valgus (VAR-CO) or remaining in valgus (VAL-rVAL) alignment may result in less preferable outcomes than correction to neutral or slightly varus alignment.

The Chitranjan S. Ranawat Award: Manipulation Under Anesthesia to Treat Postoperative Stiffness After Total Knee Arthroplasty: A Multicenter Randomized Clinical Trial

BACKGROUND

Manipulation under anesthesia (MUA) occurs in 4% of patients after total knee arthroplasty (TKA). Anti-inflammatory medications may target arthrofibrosis pathogenesis, but the data are limited. This multicenter randomized clinical trial investigated the effect of adjuvant anti-inflammatory medications with MUA and physical therapy on range of motion (ROM) and outcomes.

METHODS

There were 124 patients (124 TKAs) who developed stiffness after primary TKA for osteoarthritis enrolled across 15 institutions. All received MUA when ROM was < 90° at 4 to 12 weeks postoperatively. Randomization proceeded via a permuted block design. Controls received MUA and physical therapy, while the treatment group also received one dose of pre-MUA intravenous dexamethasone (8 mg) and 14 days of oral celecoxib (200 mg). The ROM and clinical outcomes were assessed at 6 weeks and 1 year. This trial was registered with ClinicalTrials.gov.

RESULTS

The ROM significantly improved a mean of 46° from a pre-MUA ROM of 72 to 118° immediately after MUA (P < .001). The ROM was similar between the treatment and control groups at 6 weeks following MUA (101 versus 99°, respectively; P = .35) and at one year following MUA (108 versus 108°, respectively; P = .98). Clinical outcomes were similar at both end points.

CONCLUSIONS

In this multicenter randomized clinical trial, the addition of intravenous dexamethasone and a short course of oral celecoxib after MUA did not improve ROM or outcomes. However, MUA provided a mean ROM improvement of 46° immediately, 28° at 6 weeks, and 37° at 1 year. Further investigation in regards to dosing, duration, and route of administration of anti-inflammatory medications remains warranted.

LEVEL OF EVIDENCE

Level 1, RCT.

Health Status of Total Hip Versus Total Knee Arthroplasty Patients and Possible Effects on Decisions Regarding Surgical Location, Cost, and Access to Care

Background: Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are no longer considered inpatient-only procedures. Qualifying for inpatient status reimbursement requires additional, unreimbursed administrative effort, and may limit care to these patients. Purpose: We sought to evaluate and compare the overall health status of patients receiving THA and TKA. Methods: We conducted a retrospective review evaluating 2207 patients undergoing primary THA and TKA from 2015 to 2018 at a single institution. Clinical parameters, surgical procedure, medical history, laboratory values, length of stay (LOS), and discharge location were recorded and compared between the 2 groups. Results: In 2202 patients, we observed differences for body mass index (THA = 29.4 ± 0.4, TKA = 32.1 ± 0.3), low-density lipoprotein cholesterol levels (THA = 105.8 ± 13.5 mg/dL; TKA = 128.6 ± 13.7 mg/dL), and blood glucose levels (THA = 98.2 ± 1.7 mg/dL; TKA = 101.4 ± 1.3 mg/dL), indicating that TKA patients were more likely than THA patients to be classified as obese, hypercholesterolemic, and hyperglycemic. We observed longer LOS in THA patients (51.25 hours, 95% CI ± 3.87 hours) than in TKA patients (36.93 hours, 95% CI ± 1.17 hours). A greater proportion of TKA patients were discharged home (81.97%, N = 1155) rather than to additional care facilities compared with THA patients (71.84%, N = 539). Conclusion: In this retrospective study, we observed that TKA patients had higher rates of comorbidities than did THA patients, but TKA patients spent less time in the hospital and were more likely to be discharged home. Future studies should evaluate reasons for poor clinical outcomes for patients undergoing total joint arthroplasty with an outpatient designation.

Patient Perceptions of Same-Day Discharge Versus Overnight Stay After Total Joint Arthroplasty: Results of a Survey

Background

In the COVID-19 era, there has been increasing interest in same-day discharge (SDD) after total joint arthroplasty (TJA). However, patient perception of SDD is not well reported.

Purpose

We sought to understand patients' perceptions and preferences of postoperative care by surveying patients who have completed both an overnight stay (ONS) and an SDD after TJA.

Methods

We emailed survey links to 67 patients who previously underwent either 2 total hip arthroplasties (THAs) or 2 total knee arthroplasties (TKAs).

Results

Fifty-two patients (78%) responded to the survey. Thirty-four (65%) patients underwent staged, bilateral TKAs, and 18 (35%) patients underwent staged, bilateral THAs. Overall, 63% of patients preferred their SDD, 12% had no preference, and 25% preferred their ONS, with no difference in preference between TKA and THA groups. Those who preferred their SDD reported being more comfortable at home. Those who preferred their ONS felt their pain and concerns were better addressed. No differences were found in comfort, sleep quality, appetite, burden on family, return to function, feelings of being discharged too soon, overall experience, 30-day emergency department (ED) visits, or readmissions within 30 days between patients' SDD and ONS. There was a small statistically significant difference between patients' perception of safety between SDD and ONS.

Conclusion

Our survey found that most patients reported a preference for SDD after TJA over ONS. Although there was a small difference in patient perception of safety, there were no differences in return to the ED or readmissions after SDD and ONS.

Robotic-Assisted Total Knee Arthroplasty Can Increase Frequency of Achieving Target Limb Alignment in Primary Total Knee Arthroplasty for Preoperative Valgus Deformity

Background

Robotic-assisted total knee arthroplasty (rTKA) has been shown to reduce the number of alignment outliers and to improve component positioning compared to manual TKA (mTKA). The primary purpose of this investigation was to compare the frequency of achieving target postoperative limb alignment and component positioning for rTKA vs mTKA.

Methods

A retrospective comparative study was performed on 250 patients undergoing primary TKA by 2 fellowship-trained arthroplasty surgeons. Surgeon A performed predominantly rTKA (103 cases) with the ROSA system (Zimmer Biomet, Warsaw, IN) and less frequently mTKA (44 cases) with conventional instrumentation. Surgeon B performed only mTKA (103 cases). Target limb alignment for surgeon A was 0° for all cases and for surgeon B was 2° varus for varus knees and 0° for valgus knees. Radiographic measurements were determined by 2 reviewers. Target zone was set at ± 2 degrees from the predefined target.

Results

When comparing rTKA to mTKA performed by different surgeons, there were no differences in the percentage within the target zone (57.28% vs 53.40%, P = .575), but rTKA did result in a greater percentage for cases with preoperative valgus (71.42% vs 44.12%, P = .031). Patient-reported Outcomes Measurement Information System Global-10 physical scores were statistically higher at both 3 (P = .016) and 6 months (P = .001) postoperatively for rTKA compared to mTKA performed by different surgeons.

Conclusions

Although experienced surgeons can achieve target limb alignment correction with similar frequency when comparing rTKA to mTKA for all cases, rTKA may achieve target limb alignment with more accuracy for preoperative valgus deformity.

Level of Evidence

Retrospective Cohort Study, Level III.

Management of Hip Abductor Tears and Recalcitrant Trochanteric Bursitis in Native Hips

Hip abductor tears have recently gained recognition as a more prevalent injury than previously thought. This article will detail the pathophysiology of injury, physical symptoms commonly found at presentation, diagnostic imaging to best diagnose tears and when they should be ordered, and how to properly classify the injury and finally summarize the treatment options available with expert opinions about which are most successful.

A multimodal intraosseous infusion of morphine and ketorolac decreases early postoperative pain and opioid consumption following total knee arthroplasty

BACKGROUND

Multimodal pain management regimens and intraosseous infusion of morphine are two novel techniques that show promise in decreasing postoperative pain and opioid consumption following total knee arthroplasty. However, no study has analyzed the intraosseous infusion of a multimodal pain management regimen in this patient population. The purpose of our investigation was to examine the intraosseous administration of a multimodal pain regimen comprised of morphine and ketorolac during total knee arthroplasty with regard to immediate and 2-week postoperative pain, opioid pain medication intake, and nausea levels.

METHODS

In this prospective cohort study with comparisons to a historical control group, 24 patients were prospectively enrolled to receive an intraosseous infusion of morphine and ketorolac dosed according to age-based protocols while undergoing total knee arthroplasty. Immediate and 2-week postoperative Visual Analog Score (VAS) pain scores, opioid pain medication intake, and nausea levels were recorded and compared against a historical control group that received an intraosseous infusion of morphine alone.

RESULTS

During the first four postoperative hours, patients who received the multimodal intraosseous infusion experienced lower VAS pain scores and required less breakthrough intravenous pain medication than those patients in our historical control group. Following this immediate postoperative period, there were no additional differences between groups in terms of pain levels or opioid consumption, and there were no differences in nausea levels between groups at any time.

CONCLUSIONS

Our multimodal intraosseous infusion of morphine and ketorolac dosed according to age-based protocols improved immediate postoperative pain levels and reduced opioid consumption in the immediate postoperative period for patients undergoing total knee arthroplasty.

Intraosseous Vancomycin in Total Hip Arthroplasty - Superior Tissue Concentrations and Improved Efficiency

BACKGROUND

Literature shows that intraosseous (IO) infusions are capable of providing increased local concentrations compared to those administered via intravenous (IV) access. Successes while using the technique for antibiotic prophylaxis administration in total knee arthroplasty (TKA) prompted consideration for use in total hip arthroplasty (THA) however; no study exists for the use of IO vancomycin in THA.

METHODS

This single-blinded randomized control trial was performed from December 2020 to May 2022. Twenty patients were randomized into one of two groups: IV vancomycin (15 mg/kg) given routinely, or IO vancomycin (500mg/100cc of NS) injected into the greater trochanter during incision. Serum vancomycin levels were collected at incision and closure. Soft tissue vancomycin levels were taken from the gluteus maximus (at start and end of case), and acetabular pulvinar tissue. Bone vancomycin levels were taken from the femoral head, acetabular reamings, and intramedullary bone. Adverse local/systemic reactions, 30-day and 90-day complications were also tracked.

RESULTS

A statistically significant reduction in serum vancomycin levels was seen when comparing IO to IV vancomycin at both the start and end of the procedure. All local tissue samples had higher concentrations of vancomycin in the IO group. Statistically significant increases were present within the acetabular bone reamings, and approached significance in intramedullary femoral bone.

CONCLUSION

This study demonstrates the utility of IO vancomycin in primary THA with increased local tissue and decreased systemic concentrations. With positive findings in an area without tourniquet use, IO may be considered for antibiotic delivery for alternative procedures.

Greater Trochanteric Fixation Using Cable Plate Devices in Complex Primary and Revision Total Hip Arthroplasty

Background

Successful fixation of the greater trochanter (GT) in total hip arthroplasty (THA) is a challenging task. A wide range of clinical results are reported in the literature despite advancements in fixation technology. Previous studies may have lacked adequate sample sizes to detect differences. This study evaluates nonunion and reoperation rates and determines factors influencing successful fixation of the GT using current-generation cable plate devices.

Methods

This retrospective cohort study included 76 patients who underwent surgery requiring fixation of their GT and had at least 1-year radiographic follow-up. Indications for a surgery were periprosthetic fracture (n = 25), revision THA requiring an extended trochanteric osteotomy (n = 30), GT fracture (n = 3), GT fracture nonunion (n = 9), and complex primary THA (n = 3). Primary outcomes were radiographic union and reoperation. Secondary objectives were patient and plate factors influencing radiographic union.

Results

At a mean radiographic follow-up of 2.5 years, the union rate was 76.3% with a nonunion rate of 23.7%. Twenty-eight patients underwent plate removal, reasons for removal were pain (n = 21), nonunion (n = 5), and hardware failure (n = 2). Seven patients had cable-induced bone loss. Anatomic positioning of the plate (P = .03) and number of cables used (P = .03) were associated with radiographic union. Nonunion was associated with a higher incidence (+30%) of hardware failure due to broken cable(s) (P = .005).

Conclusions

Greater trochanteric nonunion remains a problem in THA. Successful fixation using current-generation cable plate devices may be influenced by plate positioning and number of cables used. Plate removal may be required for pain or cable-induced bone loss.

Alignment options and robotics in total knee arthroplasty

Total knee arthroplasty is one of the most widely performed surgical procedures today. Its widespread popularity has helped drive innovation and improvement in the field. Different schools of thought have developed regarding the best way to perform this operation. Specifically, there are controversaries regarding the best alignment philosophy for the femoral and tibial components to optimize implant stability and longevity. Traditionally, neutral mechanical alignment has been the preferred alignment target. More recently, some surgeons advocate for alignment matching the patient's pre-arthritic anatomic alignment ("physiologic" varus or valgus), which has been described as kinematic alignment. Functional alignment is a hybrid technique that focuses on the coronal plane minimizing soft tissue releases. To date, there is no evidence demonstrating superiority of one method over another. There is growing popularity of robotic surgical techniques to improve accuracy of implant position and alignment. The choice of alignment philosophy is an important aspect of robotic assisted TKA surgery and has the potential to clarify the optimal alignment technique.

Clinical and Radiographic Outcomes of a Monoblock Fluted Titanium-Tapered Stem for Paprosky IIIa, IIIb, and IV Femoral Bone Defects

BACKGROUND

Modern fluted titanium-tapered stems (FTTS) have been increasingly utilized to achieve primary stability in conversion and revision total hip arthroplasty with major femoral bone loss. This study sought to determine the radiographic and clinical outcomes of a monoblock FTTS in patients who had major femoral bone loss.

METHODS

A multicenter retrospective observational study of all total hip arthroplasty patients who received a monoblock FTTS who had up to 5-year radiographic follow-up was conducted. Only patients with femoral Paprosky classifications of IIIa, IIIb, and IV were included. Eighty-one monoblock FTTS were examined. Median clinical follow-up was 29 months (range, 18 to 58). Stem subsidence and loosening were assessed on most recent radiographs. All-cause revisions and stem survivals were assessed.

RESULTS

Median subsidence was 1.4 millimeters (mm) (range, 0 to 15.0). Sixteen (23.9%) and 3 (4.5%) stems had subsidence greater than 5 and 10 mm, respectively. All stems not acutely revised appeared stable, without evidence of loosening, at latest follow-up. Ten hips (12.3%) required reoperations. Of these, only 5 (6.2%) stems were removed; 4 due to periprosthetic joint infection and 1 for surgical exposure during acetabular revision. Kaplan-Meier analyses yielded an all-cause stem survivorship of 95.1% at 2-years and 87.1% at 4-years. Stem survivorships excluding septic causes was 98.8% at both 2 and 4 years.

CONCLUSION

Monoblock FTTS in complex femoral reconstruction cases showed encouraging clinical and radiographic results in patients who had severe femoral bone loss at median 29 months follow-up.

Clinical Outcomes for Open Hip Abductor Repair Using Tenodesis and Bone Trough Repair Techniques

BACKGROUND

Hip abductor complex tears remain an injury without a clear consensus on management. Surgical treatment has been recommended after unsuccessful nonoperative management. This study evaluates both tenodesis and bone trough techniques, with treatment choices guided by previously described tear classification.

METHODS

This is a retrospective cohort study of 45 hips in 44 patients who underwent surgical treatment for symptomatic, chronic hip abductor tear unresponsive to nonoperative treatment. Demographics and preoperative and postoperative values (including visual analog scale pain scores, gait assessment, and muscle strength) were evaluated. Type I tears were treated using tendon tenodesis. Type II tears were treated through a bone trough repair.

RESULTS

Forty-five hips (44 patients) were operated on with a minimum of 6-month follow-up. There were 27 type I and 18 type II tears. Eighty-seven percent of patients were female. Twenty-eight percent of type II patients (5/18) had a preexisting arthroplasty in place. Significant improvements in pain (P < .001), gait (P < .001), and muscle strength (P < .001) were achieved in both the tear types. Type I repairs showed superior results to type II repairs. However, both showed significant improvements. Postoperative magnetic resonance imaging at 6 months showed healed tenodesis in 81% (17/21) of type I tears and 50% (5/10) of type II tears.

CONCLUSION

Our study shows improvement in pain and function after surgical repair of hip abductor tendon injuries in both simple and complex tears. This improvement is seen even during ongoing surgical site healing. Magnetic resonance imaging findings may remain abnormal for more than 1 year after surgery and do not clearly denote repair failure.

Cement use in total knee arthroplasty: 40 versus 80 grams

BACKGROUND

Studies of cement use in total knee arthroplasty (TKA) have historically addressed mechanical properties and application strategies. Recently, cement technique has been studied as a means to reduce cost. We transitioned from opening two bags (80 grams) of cement to one bag (40 grams) of cement for primary TKA to improve cost efficacy. This study investigates the radiographic outcome and cost of TKAs performed with 40 versus 80 grams of cement.

METHODS

TKAs from January 2017 to January 2019 were evaluated. Cement mantle and implant alignment were assessed per the Modern Knee Society Radiographic Evaluation System at four months by three blinded reviewers. Data was analyzed according to quantity of cement used. Cement mantle quality at 16 implant zones was compared. Cost was evaluated.

RESULTS

163 patients (age 66.8 yrs. +/- 8.9, 51.5% female) underwent TKA with 80 grams of cement, while 142 patients (age 67.1 yrs. +/- 9.3, 56.3% female) underwent TKA utilizing 40 grams of cement. There was no significant difference in cement mantle quality. The most common zone of cement deficiency was the femoral posterior flange (9% in 40 gram group versus 4% in 80 gram group, p value = 0.08). There was no difference in implant size. Cost saving was calculated at $7,810 for the 40 gram group.

CONCLUSION

There was no difference in radiographic cement mantle appearance between primary knees performed with 40 or 80 grams of cement. Cement usage represents a target for cost saving and opportunity to increase the value of primary TKA. Based on the current incidence of TKA in the United States, cost savings could exceed 33 million dollars annually.

2021 Chitranjan S. Ranawat Award: Intraosseous vancomycin reduces periprosthetic joint infection in primary total knee arthroplasty at 90-day follow-up

AIMS

Infection complicating primary total knee arthroplasty (TKA) is a common reason for revision surgery, hospital readmission, patient morbidity, and mortality. Increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA) is a particular concern. The use of vancomycin as prophylactic agent alone or in combination with cephalosporin has not demonstrated lower periprosthetic joint infection (PJI) rates, partly due to timing and dosing of intravenous (IV) vancomycin administration, which have proven important factors in effectiveness. This is a retrospective review of a consecutive series of primary TKAs examining incidence of PJI, adverse reactions, and complications using IV versus intraosseous (IO) vancomycin at 30-day, 90-day, and one-year follow-up.

METHODS

A retrospective review of 1,060 patients who underwent TKA between May 2016 to July 2020 was performed. There were 572 patients in the IV group and 488 in the IO group, with minimal 30 days of follow-up. Patients were followed up at regularly scheduled intervals (two, six, and 12 weeks). No differences between groups for age, sex, BMI, or baseline comorbidities existed. The IV group received an IV dose of 15 mg/kg vancomycin given over an hour preceding skin incision. The IO group received a 500 mg dose of vancomycin mixed in 150 ml of normal saline, injected into proximal tibia after tourniquet inflation, before skin incision. All patients received an additional dose of first generation cephalosporin. Evaluation included preoperative and postoperative serum creatinine values, tourniquet time, and adverse reactions attributable to vancomycin.

RESULTS

Incidence of PJI with minimum 90-day follow-up was 1.4% (eight knees) in the IV group and 0.22% (one knee) in IO group (p = 0.047). This preliminary report demonstrated an reduction in the incidence of infection in TKA using IO vancomycin combined with a first-generation cephalosporin. While the study suffers from limitations of a retrospective, multi-surgeon investigation, early findings are encouraging.

CONCLUSION

IO delivery of vancomycin after tourniquet inflation is a safe and effective alternative to IV administration, eliminating the logistical challenges of timely dosing. Cite this article: Bone Joint J 2021;103-B(6 Supple A):13-17.

Impact of Valgus vs Varus Mechanical Axis Correction During Primary Total Knee Arthroplasty on Postoperative Periarticular Bone Mineral Density

BACKGROUND

Knee periarticular bone mineral density (BMD) is influenced by limb malalignment. The purpose of this study is to determine if the nature and magnitude of alignment correction (ΔAlign°) performed during primary total knee arthroplasty (TKA) had an impact on BMD at the metaphysis of the distal femur (DFmr) and proximal tibia (PTb).

METHODS

Seventy-one patients (male = 37 |female = 34; age: 65 ± 2 years) underwent full-length standing X-rays and knee-specific BMD measurements using dual-energy X-ray absorptiometry before and 3 and 6 months following TKA. A t-test was used to compare baseline demographics and knee-specific BMD measures (medial/lateral DFmr/PTb) between patients with preoperative valgus (VAL, N = 18) and varus (VAR, N = 53) malalignment. Pearson correlation analysis was used to determine if ΔAlign° correlated with site-specific knee BMD changes. A 2 (varus/valgus) by 3 (time) analysis of variance was used to compare site-specific BMD (%ΔBMD) changes following TKA. Type I error was set at α = 0.05 for all analyses.

RESULTS

VAR patients had higher preoperative BMD for medial measurement at both the DFmr (VAR: 1.17 ± 0.06 g/cm²; VAL: 1.00 ± 0.09 g/cm²) and PTb (VAR: 1.41 ± 0.07 g/cm²; VAL: 1.29 ± 0.14 g/cm²) (P < .05). ΔAlign° and %ΔBMD were correlated on the medial side of the DFmr (r = 0.393, P < .05) and lateral/medial BMD ratio at the PTb (r = -0.670, P < .01) in VAL patients. Only VAL patients had significant %ΔBMD changes at 6 months postoperative with increases on the medial side only for the DFmr and PTb (+4%-8%, P < .05).

CONCLUSION

Valgus patients exhibited reduced medial BMD at DFmr and PTb and showed sustained improvements 6 months postsurgery. Mechanical axis correction may be clinically impactful to bone remodeling when correcting valgus malalignment.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Postoperative alignment in revision total knee arthroplasty, a comparison between intra and extra-medullary tibial alignment

BACKGROUND

Revision total knee arthroplasty commonly involves stemmed components. If the diaphysis is engaged, this technique may be problematic for mechanical alignment (MA) in cases of tibial bowing, which are not infrequent (up to 30%). The aim of this study is to compare an intra-medullary(IM) and extra-medullary(EM) alignment method. We hypothesized that IM technique and canal-filling stems may result more frequently in valgus MA. On the other hand, an EM technique could produce less valgus knees but is at risk of creating MA outliers.

METHOD

A retrospective radiographic analysis of revision TKAs was performed. The patients were divided to either the EM or IM alignment group and compared on the overall post-operative MA. The following parameters were measured on standing, long leg x-rays: Hip-knee-Ankle angle (HKA), mechanical lateral distal femoral angle and mechanical medial proximal tibial angle (mMPTA).

RESULTS

119 cases of revision TKAs were included (EM = 80, IM = 39). There was a difference between the EM and IM group for the mean mMPTA (89.94° vs 90.92°, effect size = 0.45, p = 0.013) and HKA angle (1.64° vs 0.05°, effect size = 0.52, p = 0.0064). A higher proportion of IM patients were in overall valgus alignment (16/39, 41%) vs EM group (16/80, 20%, p = 0.0134). Both techniques showed the same proportion of outliers, defined as HKA angle more than 5 degrees from neutral mechanical alignment (11/80 vs 5/39, p = 0.286).

CONCLUSION

The extra-medullary alignment method with short cemented stems creates less valgus mechanical alignment than the intra-medullary technique with press-fit stems, without creating more MA outliers.

DEXA overestimates bone mineral density in adults with knee replacements

We examined bone mineral density (BMD) measurements made by dual-energy-xray-absorptiometry (DEXA) taken from 100 patients (♂46/♀54, 66±6yr) who previously underwent single total-knee arthroplasty (TKA) to determine if automated software-based artifact detection (ASAD) adequately removes implant artifact from the DXA image before analysis and if potential inaccuracies could be overcome through manual artifact correction (MAC). We also sought to determine if software-based inaccuracies would result in fracture risk misclassification (Low-BMD/Osteopenia = Young-Adult T-Score < −1). Select Results: When using ASAD, limbs with implants had higher BMD (+12.0 ​± ​1.7%, p ​< ​0.001) compared to control limbs resulting in a 2.5 ​± ​0.2% overestimation of total-body BMD (single implant). Consequently, the prevalence of osteopenia in 95% of patients who would have been observed to have low leg BMD (18/19 patients) and 80% of those found to have low total-body BMD (4/5 patients) would have gone un-diagnosed. This overestimation was eliminated when using MAC. These results reveal a potential issue with ASAD for total-body DEXA scans in TKA patients and highlight the importance of careful review and MAC in those with joint replacements before making diagnostic decisions.

The continuum of hip range of motion: From soft-tissue restriction to bony impingement

Traditional studies of hip kinematics have not identified which anatomic structures limit the range of motion (ROM) when the hip is placed in different maneuvers. In this study, we attempted to answer two questions: (a) During which maneuvers is the motion of the hip limited by bony impingement between the femur and pelvis? (b) When is hip ROM determined by the constraint of soft tissues and to what extent? ROM of eight cadaveric hips was measured in 17 maneuvers using a motion capture system. The maneuvers were recreated in silico using 3D CT models of each specimen to detect the occurrence of bony impingement. If bony impingement was not detected, the variable component of 3D hip motion was increased until a collision was detected. The difference between the virtual ROM at the point of bony impingement and the initial ROM measured experimentally was termed as the soft-tissue restriction. The results showed that bony impingement was present in normal hips during maneuvers consisting of high abduction with flexion, and high flexion combined with adduction and internal rotation. At impingement-free maneuvers, the degree of soft tissue restriction varies remarkably, ranging from 4.9° ± 3.8° (internal rotation) at 90° of flexion to 80.0° ± 12.5° (internal rotation) at maximum extension. The findings shed light on the relative contributions of osseous and soft tissues to the motion of the hip in different maneuvers and allow for a better understanding of physical exams of different purposes in diagnosing bone- or soft tissue-related diseases.

Open Hip Abductor Tendon Repair into a Bone Trough: Improved Outcomes for Hip Abductor Tendon Avulsion

Hip abductor tendon tears are a well-recognized entity that results in progressive lateral hip pain, weakness, and limping. These can occur in patients with native hips or in patients following total hip arthroplasty. However, treatment of these 2 distinct groups does not differ. We describe a new repair technique utilizing a longitudinal bone trough in the greater trochanter. We compare our results (focusing on gluteus medius tendon avulsions) and traditional repair with suture anchors or transosseous bone tunnels. Additionally, we propose a classification system that attempts to describe the different types of tears to guide treatment, as the current classification system is not helpful in defining pathology or guiding treatment. Our proposed classification will help to better describe tear types anatomically and thereby guide appropriate surgical interventions based on these types.

Short-Stem Prostheses in Total Hip Arthroplasty: An Unexpected Short-Term Complication: A Report of 2 Cases

CASE

We present here 2 cases of postoperative stress fractures in the setting of a short-stem implant. Both patients had well-aligned implants with good bone quality and presented with delayed onset and atraumatic thigh pain. They were diagnosed with periprosthetic fractures around stable implants.

CONCLUSIONS

We now reserve the use of these stems for patients who have femoral morphology and are unable to accept standard stems. Patients who complain of new-onset thigh pain in the setting of short-stem total hip arthroplasty should have a femoral stress fracture included in the differential diagnosis and be worked up appropriately.

Clinical outcome evaluation of intraosseous vancomycin in total knee arthroplasty

Background

Vancomycin is a commonly used prophylactic antibiotic for total joint replacement surgery to protect against methicillin-resistant Staphylococcus aureus. Studies have suggested intraosseous (IO) infusions provide superior local tissue antibiotic concentration compared with intravenous (IV) access in total knee arthroplasty (TKA). We reviewed patients receiving IO vancomycin before TKA, comparing complication rates to a matched group receiving IV prophylactic vancomycin.

Methods

Retrospective review of TKA patients administered IO vancomycin (500 mg vancomycin in 200 mL normal saline), September 1, 2018 to March 1, 2019, was compared with TKAs performed with prophylactic IV vancomycin, January 1, 2018 to August 31, 2018. Before incision, an IO needle was inserted into the tibial tubercle region, delivering 100 mL of the mixed vancomycin solution. The needle was then removed and inserted into the distal femur, delivering 100 mL of the solution. Evaluation included preoperative and postoperative creatinine values, tourniquet time, and knee-related 30-day and 90-day complications. Data for primary and revision TKA surgery cases were analyzed independently.

Results

There were 100 primary and 29 revision TKA cases in the control (IV) arm and 100 primary and 19 revision TKA cases in the intervention (IO) arm, comprising a study group of 248 cases. There were fifteen 30-day complications and eighteen 90-day complications overall. No significant differences in the complication rate or creatinine values were identified between IO and IV groups.

Conclusions

IO vancomycin has an adequate safety profile in primary and revision TKA, eliminating the logistical challenge of timely prophylactic antibiotic administration.

The Usefulness of Meta-Analyses to Hip and Knee Surgeons

BACKGROUND

Comprehensive systematic reviews of results from homogenous or heterogeneous clinical trials, meta-analyses are used to summarize and to interpret studies. Proponents believe that their use can increase study power and improve precision results. Critics emphasize that heterogeneity between studies and bias of individual studies compromise the value of results. The methodology of meta-analyses has improved over time, utilizing statistical analysis to reduce bias and examining heterogeneity. With an increasing trend of meta-analyses in orthopaedic literature, this study aimed to investigate quality and clinical utility of meta-analyses for total knee arthroplasty and total hip arthroplasty.

METHODS

A systematic review of total knee arthroplasty and total hip arthroplasty meta-analyses in 3 major orthopaedic journals from January 2000 to August 2017 was performed. Three authors independently reviewed eligible meta-analyses. A quality assessment was conducted using the Oxman-Guyatt Index. Reporting quality was assessed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Two high-volume, fellowship-trained, attending surgeons specializing in total hip arthroplasty and total knee arthroplasty independently, in a blinded fashion, reviewed 24 of the highest-scored meta-analyses.

RESULTS

There were 114 studies meeting eligibility criteria, 25 published from 2000 to 2009 and 89 published from 2010 to 2017, a 3.6-fold increase. The mean Oxman-Guyatt Index score was 3.89 points, with 12 high-quality studies, 87 moderate-quality studies, and 15 low-quality studies. The mean PRISMA score for all meta-analyses was 22.2 points, with 79% classified as low to moderate. Only 23 studies listed the Level of Evidence, and 8 were Level-I studies and 9 were Level-II studies. Studies with >15 randomized controlled trials were associated with higher PRISMA and Oxman-Guyatt Index scores. In 12 articles, we were unable to decipher the types of studies included. Only 39.4% of studies showed the risk of bias. Of the 24 studies identified as high quality per the PRISMA statement, 71% were determined to be either clinically unimportant or inconclusive.

CONCLUSIONS

The number of total hip arthroplasty and total knee arthroplasty meta-analyses has markedly increased over the past decades. The majority of published meta-analyses from 3 major orthopaedic journals were not performed in accordance with established PRISMA guidelines.

CLINICAL RELEVANCE

Many published meta-analyses are low to moderate quality, and clinicians should cautiously draw conclusions from poorly executed meta-analyses.

Drug reaction with eosinophilia and systemic symptoms syndrome after total knee arthroplasty infection and placement of antibiotic spacer

Though 2-stage revision is considered the gold standard in North America for treatment of periprosthetic joint infection, complications can be associated with use of antibiotic-impregnated spacers. We present a unique case of drug reaction with eosinophilia and systemic symptoms syndrome in a patient with retained antibiotic-impregnated spacer placed for the treatment of a periprosthetic joint infection. Although drug reactions in general are common, severe drug reactions like the one described in this article are exceedingly rare. After discontinuation of intravenous antibiotics and the initiation of corticosteroids, the patient’s symptoms resolved, despite retention of the spacer. Steroid administration and supportive care may result in resolution of symptoms without the need for surgical intervention for spacer removal.

Hypothermia in Total Joint Arthroplasty: A Wake-Up Call

BACKGROUND

Total joint patients are particularly vulnerable to perioperative hypothermia (PH) (combined effects of anesthesia, radiation, and convective heat loss from exposed skin surfaces and cool temperatures in the operating room). There are limited studies on PH in these patients.

METHODS

In a retrospective review of 204 patients undergoing primary hip and 179 undergoing primary knee replacement surgeries, time and temperature parameters were collected from the electronic health records from preoperative and postoperative recovery room nursing assessments, intraoperative anesthesia records, and floor nursing notes. Basic patient demographic data was recorded. Chi-squared and paired t-tests were used to compare between hypothermic and normothermic groups.

RESULTS

At the time of incision, 60 of 179 (34%) total knee arthroplasty (TKA) patients and 80 of 204 (39%) total hip arthroplasty (THA) patients were hypothermic. In THA patients, 65% remained hypothermic for the duration of anesthesia compared to 33% of TKA patients. The largest drop in core body temperature in both THA and TKA patients occurred between preoperative holding and induction of anesthesia. In THA patients, spinal anesthesia had a significantly higher occurrence of PH. No significant patient factor was found to increase risk.

CONCLUSION

Emphasis on preoperative holding protocols, decreasing time from operating room entry to incision, and increasing ambient room temperature could reduce risk of hypothermia in total joint replacement patients.

Antibiotic impregnated total femur spacers: a technical tip

Simultaneous prosthetic joint infection of ipsilateral hip and knee arthroplasties is often accompanied by significant bone loss and presents a challenging reconstructive problem. Two-stage reconstruction is favored and requires the placement of a total femur spacer, which is not a commercially available device. We describe a surgical technique, reporting on 2 cases in which a customized total femur antibiotic impregnated spacer was created by combining an articulating knee spacer and an articulating hip spacer with a reinforced cement dowel construct connecting the 2 spacers. Custom total femoral spacers are useful in the management of infected femoral megaprostheses and cases with ipsilateral injected hip and knee arthroplasties and severe femoral bone loss.

Corrosion and adverse local tissue reaction after total hip arthroplasty with a modular titanium alloy femoral neck

This report describes a case of mechanically assisted crevice corrosion and secondary adverse local tissue reaction in a patient following a total hip arthroplasty, utilizing a modular neck (bi-modular) femoral component. Radiographic evaluation demonstrated a well-positioned, stable, cementless arthroplasty. Upon further evaluation, the patient had elevated serum cobalt and chromium levels, and magnetic resonance imaging demonstrated a periprosthetic pseudotumor. Corrosion of both the neck-stem and head-neck junctions was suspected. At the time of surgery, the neck-body junction was pristine; however, the head-neck junction of the implant demonstrated severe corrosive wear, a problem that has been reported only once previously with this particular bi-modular implant. This serves as a reminder that any modular junction may be susceptible to corrosion and not all bi-modular designs behave similarly.

Will New Metal Heads Restore Mechanical Integrity of Corroded Trunnions?

BACKGROUND

Metal wear and corrosion from modular junctions in total hip arthroplasty can lead to further unwanted surgery. Trunnion tribocorrosion is recognized as an important contributor to failure. This study was performed to determine if new metal heads restore mechanical integrity of the original modular junction after impaction on corroded trunnions, and assess which variables affect stability of the new interface created at revision total hip arthroplasty.

METHODS

Twenty-two trunnions, cobalt-chromium (CoCr) and titanium alloy (TiAIV), (CoCr, n = 12; TiAIV, n = 10) and new metal heads were used, 10 trunnions in pristine condition and 12 with corrosion damage. Test states were performed using an MTS Machine and included the following: 1, Assembly; 2, Disassembly; 3, Assembly; 4, Toggling; and 5, Disassembly. During loading, three-dimensional motion of the head-trunnion junction was measured using a custom jig.

RESULTS

There were no statistical differences in the tested mechanical properties between corroded and pristine trunnions implanted with a new metal femoral head. Average micromotion of the head versus trunnion interface was greatest at the start of loading, stabilizing after approximately 50 loading cycles at an average of 30.6 ± 3.2 μm.

CONCLUSION

Corrosion at the trunnion does not disrupt mechanical integrity of the junction when a CoCr head is replaced with a CoCr trunnion. However, increased interface motion of a new metal head on a corroded titanium trunnion requires additional study. The evaluation of ball head size on mechanical integrity of trunnions would also be a potential subject of future investigation, as increasing the ball head size at the time of revision is not uncommon in revisions today.

External fixator immobilization after extensor mechanism reconstruction in total knee arthroplasty

Extensor mechanism disruption after total knee arthroplasty is a complicated problem that typically requires surgical reconstruction. After extensor mechanism failure, reconstruction is typically indicated to restore active knee extension and provide a stable limb for ambulation. Immobilization of the knee in extension is vital in the initial postoperative period after extensor mechanism reconstruction. We describe a series of 4 patients who underwent extensor mechanism reconstruction followed by external fixator application to maintain the knee extended in the initial postoperative period. Our results have been favorable. However, close follow-up is important to monitor for the development of pin site infections.

Stemmed tibial revision component alignment: Does an anatomic conflict exist?

INTRODUCTION

Obtaining satisfactory coronal plane alignment is important for success in revision total knee arthroplasty (TKA). The study objective was to determine tibial coronal plane alignment after TKA when a tibial stem was used and assess if there was an anatomic conflict in tibial stemmed component alignment.

MATERIALS AND METHODS

A radiographic review of 88 revision TKA cases was performed. Full length leg radiographs were examined for varus/valgus alignment, defined as greater than or equal to three degrees from neutral 180 degrees, canal or non-canal filling tibial stems, and any native tibial bow.

RESULTS

In tibias with a native valgus alignment of three or more degrees, a canal-filling stem allowed little flexibility to improve final positioning of the tibial stem and resulted in a valgus alignment of the tibial stem in 87.5% of cases, where a canal filling stem was utilized. A non-canal filling stem utilized in native valgus tibias allowed on average a two-degree improvement in tibial alignment and 64.7% of cases resulted in a neutral placement of the tibial stem.

CONCLUSION

Implanting the tibial component in a desired position is limited by type of stem and the native angulation of the tibia. When anatomic conflict exists between tibial mechanical axis and the intramedullary canal, canal filling stems may compromise coronal alignment.

Quantifying and Predicting Surgeon Work Effort for Primary and Revision Total Knee Arthroplasty

BACKGROUND

The objectives of this study were to quantify increased utilization of resources in revision total knee arthroplasty (TKA) compared with primary TKA, determine preoperative factors that predict outcome measures, and compare Medicare reimbursement for each procedure.

METHODS

Seventy-eight revision TKA patients were compared with 80 primary TKA patients. Outcomes measured were surgical time, estimated blood loss, length of stay, and complications.

RESULTS

Revision TKA showed 49% increased surgical time compared with primary TKA. Estimated blood loss was increased 91%. Tibial and femoral bone loss was associated with increased surgical time as was use of longer stemmed tibial components. Average Medicare hospital payment increased 29% ($13,464 for primary, $17,331 for revision). Average physician reimbursement represented a 36% increase. Relative value units were increased to 31%.

CONCLUSION

There was substantial increase in work effort not commensurate with current Medicare reimbursement, which may limit patient access to revision TKA.

Eighty-six Percent Failure Rate of a Modular-Neck Femoral Stem Design at 3 to 5 Years: Lessons Learned

BACKGROUND

While innovation drives advancement, it is not immune to failure. Previously, we reported a corrosion-related revision rate of 28% (23 of 81 total hip arthroplasties) among patients who received the Rejuvenate modular-neck stem implant with short-term follow-up. Because we observed a dramatic interval failure rate after our initial report, we undertook this study.

METHODS

We prospectively followed a cohort of patients who had undergone implantation of the Rejuvenate modular-neck stem, as previously reported. At a minimum of 3 years of follow-up (range, 3.0 to 5.5 years), 73 hips in 63 patients (90% of the original group) were available for analysis. The mean serum cobalt and chromium ion levels were obtained preoperatively and postoperatively. Elevated serum cobalt ion levels (>4 μg/L), pain, or abnormal magnetic resonance imaging (MRI) findings were indications for revision surgery. Patient factors and serum metal ion levels were correlated to revision surgery. Additionally, post-revision serum cobalt and chromium ion level trends were assessed.

RESULTS

An 86% clinical failure rate (63 of the 73 hips) was observed at a mean follow-up of 4.2 ± 0.6 years (range, 3.0 to 5.5 years); 57 (78%) of the hips underwent revision at a mean of 3.2 ± 1.0 years (range, 1.0 to 5.5 years), and 6 (8%) of the hips were scheduled for revision. Patients who underwent revision surgery were younger and had greater serum metal ion levels and greater pain compared with patients who did not undergo revision. An elevated serum cobalt ion level was the most important independent factor associated with revision surgery. Cobalt ion levels decreased sharply after revision; however, some patients demonstrated persistent elevation with more gradual decline.

CONCLUSIONS

Emphasizing the reporting of positive results may leave orthopaedic surgeons reticent to publicize negative results; however, the high failure rate of this implant design within 5 years prompted this report. We believe that patients and orthopaedic surgeons should be made aware of this implant's clinical problems and patients should be followed closely. Expedient revision is necessary when failure is identified, to minimize potentially severe tissue damage and metal toxicity.

LEVEL OF EVIDENCE

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

Trochanteric impingement: is it a source of pain after THR?

While uncommon, trochanteric-pelvic impingement may lead to significant lateral hip pain. We defined “impingement distance” as the radiographic distance from the medial aspect of the greater trochanter and the corresponding lateral edge of the acetabular bone or component and compared this to the contralateral normal hip. We present two painful total hip replacement (THR) cases, each featuring a patient with severe lateral hip pain when walking and sitting. Both patients had diminished femoral offset and trochanteric-pelvic clearance, compared to the contralateral normal hip. The impingement distance was increased an average of 10 mm with the exchange to a longer femoral head. Both patients had immediate and complete pain relief with operative treatment to increase the impingement distance.

Tibial Stems in Revision Total Knee Arthroplasty: Is There an Anatomic Conflict?

Tibial stems are frequently used in revision total knee arthroplasty (TKA). We investigated the effect of tibial stems on final component alignment and tray position. Thirty 3D reconstructed cadaveric tibial models were classified according to canal bow angle. After virtual implantation of 120 mm and 200 mm stemmed tibial components, deviation from native mechanical axis was measured. Tibial alignment valgus malposition of up to three degrees occurred and most pronounced with 120 mm stems. Canal alignment using 200 mm stems deviated tray position medially and posteriorly. Mild to moderate valgus bowing of the tibial canal is not uncommon (57% in our series) possibly leading to valgus malalignment. Anatomic conflict between the tibial mechanical axis and intramedullary canal can exist, with alignment and tray placement implications.

Anteroposterior Knee Stability During Stair Descent

This study examined the influence of tibio-femoral conformity on anteroposterior (AP) knee stability during stair descent, particularly with a dished cruciate sacrificing (CS) design. A joint simulator simulated stair descent of cadaveric knees. Tibio-femoral displacement was measured. Knees were tested in intact, ACL-deficient, and TKA with cruciate-retaining (CR), CS and posterior-stabilizing (PS) inserts. Loading during stair descent simulation caused femur displacement anteriorly prior to quadriceps contraction. Quadriceps contraction reestablished the initial femoral AP position. During simulated stair descent, AP stability was restored using PS, CR or CS inserts with an intact PCL. The CS design without the PCL did not provide AP stability. Increasing quadriceps force to restore AP stability may explain the clinical findings of pain and fatigue experienced by some patients after TKA.

Early corrosion-related failure of the rejuvenate modular total hip replacement

BACKGROUND

The Rejuvenate modular-neck stem implant (Stryker Orthopaedics, Mahwah, New Jersey) was recently recalled due to corrosion at the femoral neck-stem junction. The purpose of this study was to investigate the rate of corrosion-related failure and survivorship of this implant and analyze the correlation of implant and patient factors with serum metal ion levels and revisions.

METHODS

From June 2009 to July 2012, 123 Rejuvenate total hip arthroplasty stems (ninety-seven modular and twenty-six non-modular) were implanted in 104 patients by a single surgeon. Serum cobalt (Co) and chromium (Cr) levels (micrograms per liter [μg/L]) were measured postoperatively for all patients. Patients with persistent hip pain or elevated metal ion levels underwent magnetic resonance imaging for assessment of osteolysis or adverse local tissue reactions. Correlation of implant factors (stem size, head size, head length, and femoral head-neck offset) and patient factors (age, sex, and body mass index) with serum metal ion levels and revisions were analyzed with use of logistic regression models.

RESULTS

The mean duration of follow-up (and standard deviation) was 2.7 ± 0.6 years. The mean Co and Cr levels were 5.4 ± 5.7 μg/L (range, 0.2 to 31 μg/L) and 2.1 ± 1.5 μg/L (range, 0.1 to 4.3 μg/L), respectively. The differences in Co and Cr levels between the two groups (modular and non-modular) were significant: 48% of the total hip arthroplasties in the modular group resulted in elevated metal ion levels (Co >4.0 μg/L and Cr >2.0 μg/L; p < 0.05). The metal ion levels in the non-modular group were normal. In the modular group, higher metal ion levels were significantly correlated with younger age and a higher femoral head-neck offset (p = 0.04). Pain and high Co serum levels were significant predictors of revision surgery (p = 0.006). The rate of revision at the time of this study was 28% in the modular group, with the majority of the revisions performed in the second year after surgery; the Kaplan-Meier survivorship was 40% at four years.

CONCLUSIONS

The short-term high rate of corrosion-related revision with Rejuvenate modular-neck stems is striking.

Maximizing tibial coverage is detrimental to proper rotational alignment

BACKGROUND

Traditionally, the placement of the tibial component in total knee arthroplasty (TKA) has focused on maximizing coverage of the tibial surface. However, the degree to which maximal coverage affects correct rotational placement of symmetric and asymmetric tibial components has not been well defined and might represent an implant design issue worthy of further inquiry.

QUESTIONS/PURPOSES

Using four commercially available tibial components (two symmetric, two asymmetric), we sought to determine (1) the overall amount of malrotation that would occur if components were placed for maximal tibial coverage; and (2) whether the asymmetric designs would result in less malrotation than the symmetric designs when placed for maximal coverage in a computer model using CT reconstructions.

METHODS

CT reconstructions of 30 tibial specimens were used to generate three-dimensional tibia reconstructions with attention to the tibial anatomic axis, the tibial tubercle, and the resected tibial surface. Using strict criteria, four commercially available tibial designs (two symmetric, two asymmetric) were placed on the resected tibial surface. The resulting component rotation was examined.

RESULTS

Among all four designs, 70% of all tibial components placed in orientation maximizing fit to resection surface were internally malrotated (average 9°). The asymmetric designs had fewer cases of malrotation (28% and 52% for the two asymmetric designs, 100% and 96% for the two symmetric designs; p < 0.001) and less malrotation on average (2° and 5° for the asymmetric designs, 14° for both symmetric designs; p < 0.001).

CONCLUSIONS

Maximizing tibial coverage resulted in implant malrotation in a large percentage of cases. Given similar amounts of tibial coverage, correct rotational positioning was more likely to occur with the asymmetric designs.

CLINICAL RELEVANCE

Malrotation of components is an important cause of failure in TKA. Priority should be given to correct tibial rotational positioning. This study suggested that it is easier to balance rotation and coverage with asymmetric tibial baseplates; clinical research will need to determine whether the observed difference affects patellar tracking, loosening rates, or the likelihood of revisions after TKA.

Surgical Technique for Implantation of Articulating Spacers with Stem Extensions for Treatment of Infection Following Total Knee Arthroplasty

Introduction

This article describes our technique of adding a custom-made antibiotic-coated stem to an articulating spacer to improve fixation and effectively deliver antibiotics to the medullary canal in the treatment of infection following total knee arthroplasty.

Step 1 Obtain Items Required for Intraoperative Assembly

Make sure all required items are ready prior to the start of the operation.

Step 2 Remove the Components and Perform Thorough Debridement

Remove the components and debride all cement and necrotic, devitalized, and infected tissue.

Step 3 Size the Spacers

Use the polyethylene insert to size the tibial spacer and the anteroposterior dimension of the explanted femoral component to size the femoral spacer.

Step 4 Construct the Stems

Divide the rod, coat the rods with antibiotic cement, and connect them to the articulating components.

Step 5 Implant the Spacers

Apply the cement only to the metaphysis and undersurface of the tibial spacer and place a large amount of cement on the medial and lateral condyles of the femoral spacer.

Step 6 Postoperative Protocol

Patients should walk with partial weight-bearing with a brace locked in extension for three to four weeks.

Results

The above technique using the articulating spacers with stem extension was employed in a two-stage revision arthroplasty to treat thirty-three patients with infection at the site of a primary or revision total knee arthroplasty³.

What to Watch For

IndicationsContraindicationsPitfalls & Challenges.

Does an enhanced surface finish improve acetabular fixation in revision total hip arthroplasty?

High-porosity "cancellous metal" coatings have been introduced to increase the fixation and biologic incorporation of acetabular cups. The strength of initial fixation provided by a cancellous metal cups vs conventional alternatives in the deficient revision acetabulum was investigated. Cancellous, plasma-sprayed, and beaded cups (n = 9) were implanted under controlled conditions into a validated model of the revision acetabulum. The greatest differences were seen in resistance to catastrophic (spin-out) failure that, for the cancellous shell, averaged 1076 ± 265 N, which was 25% greater than the plasma-sprayed implant (859 ± 214 N, P = .04) and 218% greater than the beaded implant (338 ± 123 N, P < .01). The cancellous coating also provided greater resistance to ultimate failure. These results suggest that these new cancellous metal coatings may represent a promising alternative for fixation in revision total hip arthroplasty.

Which procedure better restores intact hip range of motion: total hip arthroplasty or resurfacing? A combined cadaveric and computer simulation study

Previous comparisons of hip range of motion (ROM) after THA and surface replacement arthroplasty (SRA) are inconclusive due to the lack of soft tissue considerations and dissimilar control groups. The normal ROMs of 8 intact cadaveric hips were determined by placing specimens in 6 discrete, predefined positions of rotation at a standard torque. In each position, the limiting factor of ROM, either bony impingement or soft tissue restriction, could be determined. Total hip arthroplasty and SRA components were virtually implanted, and ROM until impingement was determined. With a THA, the ROM was comparable to that of the intact hip. With an SRA, flexion (111° ± 13°) was less than for the intact hip (131° ± 6°). Surface replacement arthroplasty, but not THA, significantly decreases the ROM compared to intact hips.

Does acetabular retroversion affect range of motion after total hip arthroplasty?

BACKGROUND

Increasingly, acetabular retroversion is recognized in patients undergoing hip arthroplasty. Although prosthetic component positioning is not determined solely by native acetabular anatomy, acetabular retroversion presents a dilemma for component positioning if the surgeon implants the device in the anatomic position.

QUESTIONS/PURPOSES

We asked (1) whether there is a difference in ROM between surface replacement arthroplasty (SRA) and THA in the retroverted acetabulum, and (2) does increased femoral anteversion improve ROM in the retroverted acetabulum?

METHODS

Using a motion analysis tracking system, we determined the ROM of eight cadaveric hips and then created virtual CT-reconstructed bone models of each specimen. ROM was determined with THA and SRA systems virtually implanted with (1) the acetabular component placed in 45° abduction and matching the acetabular anteversion (average 23° ± 4°); (2) virtually retroverting the bony acetabulum 10°; and (3) after anteverting the THA femoral stem 10°.

RESULTS

SRA resulted in ROM deficiencies in four of six maneuvers, averaging 25% to 29% in the normal and retroverted acetabular positions. THA restored ROM in all six positions in the normal acetabulum and in four of the six retroverted acetabula. The two deficient positions averaged 5% deficiency. THA with increased femoral stem anteversion restored ROM in five positions and showed only a 2% deficiency in the sixth position. Compared with the intact hip, ROM deficits were seen after SRA in the normal and retroverted acetabular positions and to a lesser extent for THA which can be improved with increased femoral stem anteversion.

CONCLUSION

Poor ROM may result after SRA if acetabular retroversion is present.

Guidelines for implant placement to minimize impingement during activities of daily living after total hip arthroplasty

Impingement, both prosthetic and bony, precedes the vast majority of dislocations after total hip arthroplasty and may adversely impact component wear. Reconstructed computer hip models of 8 subjects were used to evaluate hip range of motion for activities of daily living (ADLs) associated with posterior instability and anterior instability. Variables examined included acetabular position, femoral offset, and head size. The majority of flexion ADLs (associated with posterior instability) encountered prosthetic impingement, whereas extension ADLs demonstrated bony impingement with the 45/20 cup placement position. Cup placement in natural anteversion and adduction allowed normal joint motion in anterior and posterior impinging activities. Insufficient femoral offset and smaller head size negatively impacted range of motion. Any anterior cup and posterior cup protrusions greater than 5 mm should be avoided.

Vesicoacetabular fistula in a chronically infected total hip arthroplasty

Fistula formation between the bladder and acetabulum related to total hip arthroplasty (THA) is rare, and few cases have been documented. Common features of the reported cases include a defect in the medial wall of the acetabulum, a chronically infected THA, a history of bladder injury, vesicocutaneous fistulas, and a history of pelvis radiation exposure. We report the case of a vesicoacetabular fistula discovered during antibiotic spacer placement in a woman with a chronically infected THA. The patient received bilateral ureteral stents extending from the renal pelvis to the urethra. Three months later, the patient was free of infection and was able to undergo reimplantation arthroplasty.