Can We Improve Screening Costs in Asymptomatic Metal on Metal Total Hip Arthroplasties?

Introduction: Metal on Metal (MoM) total hip arthroplasty (THA) has been largely abandoned in the United States secondary to high failure rates. Many of the failures are attributed to adverse local tissue reactions (ALTR). Therefore, patients that have a MoM THA are routinely screened by checking serum metal ion levels every two years, as was recommended by the FDA. However, there is limited data on the costs of current screening protocols. Materials and Methods: 318 consecutive patients who underwent a MoM THA at a single institution were retrospectively enrolled. The average follow-up was 8.2 years. Clinical data, metal ion levels, revision and reoperation rates were prospectively collected. The costs of clinical screening for this patient population was calculated and compared to the cost of an annual screening protocol. Results: 12 patients had either an elevated Co or Cr level (>4.5 ppb). Eight patients were revised secondary to ALTR. The total cost of screening during the study was $612,250. Additionally, if annual screening had been performed, total screening costs would be approximately $1,719,200. Discussion: Eight patients in the following study were revised secondary to ALTR with a total cost of screening of $612,500. These costs are substantially less than the cost of annual screening ($1,719,200). Due to the considerable costs of screening asymptomatic MoM THA patients, we recommend both optimizing the frequency of screening and evaluating the specific risk of the implant being screened. 

Is Utilizing a Modular Stemmed Tibial Component in Obese Patients Undergoing Primary Total Knee Replacement Cost-Effective?

Introduction: There has been recent enthusiasm for the use of modular stemmed tibial components in obese (BMI ≥35kg/m2) patients undergoing primary total knee arthroplasty (TKA). This has been mainly driven by studies demonstrating statistically significant increases in the rates of aseptic tibial loosening (ATL) in this patient population. However, to our knowledge, no study has specifically evaluated the cost effectiveness of this current recommendation.Methods: The following study was performed utilizing previously obtained data on the incidence of ATL in obese patients undergoing primary TKA. This data was then utilized to create a cost calculator that can evaluate the price point at which the use of a stemmed tibial component in all obese patients would be less than or equal to the costs of revision surgery if a stemmed implant was not utilized.Results: Utilizing historical data with a revision rate of 4% for aseptic loosening of the tibia on obese patients, a cost calculator was developed. The cost calculator requires the input of expected or known incidence of ATL utilizing a stem extension and the expected or known costs of revision for ATL.Conclusion: The following cost calculator quickly determines a price point at which the use of a tibial stem offsets the costs of revision surgery. While this study may not provide an exact cost-effectiveness of modular stem fixation due to model limitations, it will hopefully initiate the discussion for providing more cost-effective individualized care for this patient population.

Correction to: Direct oral anticoagulants for the treatment of venous thromboembolism in patients with active malignancy: a systematic review and meta-analysis

Unfortunately the author list in the original article is incomplete. The correct list of contributing authors is given in this Correction.

Revision Total Knee Arthroplasty for Arthrofibrosis

BACKGROUND

Arthrofibrosis after TKA is a significant cause of patient dissatisfaction. There is little evidence regarding revision arthroplasty in this patient population. The purpose of this study is to evaluate outcomes after revision TKA for arthrofibrosis.

METHODS

We retrospectively reviewed 46 consecutive revision TKAs for arthrofibrosis between 2007 and 2015 with minimum 2-year follow-up. Range of motion (ROM), complication rates, and Knee Society Scores (KSS) were recorded.

RESULTS

Patients were followed for a mean of 59 months. ROM and KSS significantly improved: with flexion improving from 88° to 103° and extension improving from 11° to 3° (P < .001). There was not a relationship between patient or surgical factors and outcomes in this study. The rate of complications was 28.2% with a 17.4% reoperation rate.

CONCLUSION

While revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, caution is advised given high rates of revisions, reoperations, and complications. Thirty percent of patients in this series had a decrease in one or more component of the KSS or a net decrease in arc of motion after revision surgery.

Midterm Prospective Comparative Analysis of 2 Hard-on-Hard Bearing Total Hip Arthroplasty Designs

INTRODUCTION

Hard-on-hard (HoH) bearing surfaces in total hip arthroplasty (THA) are commonly utilized in younger patients and may decrease mechanical wear compared to polyethylene bearing surfaces. To our knowledge, no study has prospectively compared the 2 most common HoH bearings, ceramic-on-ceramic (CoC) and metal-on-metal (MoM) THA.

MATERIALS AND METHODS

We prospectively enrolled 40 patients to undergo an MoM THA and 42 patients to undergo a CoC THA utilizing the same acetabular component. Patients were followed up for a minimum of 2 years. Comparative outcomes included clinical scores, revision or reoperation for any reason, complication rates, and radiographic outcomes.

RESULTS

The average follow-up was significantly longer in the CoC cohort (94 vs 74 months; P = .005). The CoC cohort had significantly improved Harris Hip Scores (95 vs 84; P = .0009) and pain scores (42 vs 34; P = .0003). The revision (0% vs 31%; P = .0001), reoperation (7.5% vs 36%; P = .004), and complication rates (10% vs 56%; P = .0001) were significantly lower in the CoC cohort. There were no statistically significant differences in radiographic parameters.

CONCLUSION

The clinical outcomes in the CoC cohort exceeded the MoM cohort. It is unlikely that another prospective comparative study of HoH THAs will be conducted. Our midterm results support the use of CoC THA as a viable option that may reduce long-term wear in younger patients. Close surveillance of MoM THA patients is recommended considering the higher failure and complication rates reported in this cohort.

Radiographic Findings in Patients With Catastrophic Varus Collapse After Total Knee Arthroplasty

BACKGROUND

Catastrophic varus collapse is an uncommon mechanism of failure in primary total knee arthroplasty (TKA). Varus collapse has been associated with obesity and smaller implant sizes. However, to our knowledge, preoperative radiographic characterization of this cohort has not been performed. Therefore, the following study evaluated preoperative alignment and how this correlates with the degree of eventual varus collapse identified in this patient population prior to revision.

METHODS

Utilizing our institutional database, 1106 revision TKAs were performed from 2004 to 2017. Of these, 35 patients were revised secondary to tibial varus collapse. Twenty-seven patients had their primary TKA performed at our institution. Coronal alignment of the knee was recorded from anteroposterior knee radiographs. Medial tibial bone loss was recorded at final follow-up.

RESULTS

The average body mass index was 38 kg/m². Twenty-six of 27 patients had a preoperative varus deformity (4.2° varus) and all were corrected to a valgus coronal alignment immediately postoperatively (5.2° valgus, P = .0001). Twenty-four of 27 patients' coronal alignment after varus collapse was within 2° of their preoperative alignment (5.8° varus). Twenty-five of 27 patients had radiographic medial tibial bone loss prior to varus collapse.

CONCLUSION

Tibial varus collapse in an uncommon cause of failure after primary TKA. Preoperative varus deformity, postoperative medial tibial bone loss, and obesity were common findings in this series of patients. Therefore, increased tibial stem lengths should be considered in patients with a preoperative varus deformity, small tibial implant size, and a body mass index ≥35 kg/m² undergoing primary TKA.

A Retrospective Comparative Analysis of the Use of Implantable Bone Stimulators in Nonunions

This study details the use of implantable bone stimulators in the setting of nonunion. A retrospective comparative analysis was used to evaluate the efficacy of implantable bone stimulators in achieving union in the setting of atrophic or oligotrophic nonunion by two fellowship-trained orthopaedic trauma surgeons. Initially, 72 patients underwent surgical intervention for nonunion. Twenty-one patients had an implantable bone stimulator placed at the time of nonunion surgery. Thirty-eight patients had a minimum of 1-year follow-up. An implantable bone stimulator was used in 13 patients and 25 patients did not have a bone stimulator. The use of implantable bone stimulators was found to be significantly associated with increased union rates (p = .042). (Journal of Surgical Orthopaedic Advances.

Coronal alignment predicts the use of semi-constrained implants in contemporary total knee arthroplasty

BACKGROUND

Semi-constrained, or varus-valgus constrained, implants are occasionally necessary to achieve stability in primary total knee arthroplasty (TKA). However, outcomes with these implants are largely unknown. Therefore, the primary goals of this study were to determine 1) can we identify preoperatively which patients might require a semi-constrained implant and 2) are there any clinical and or radiographic differences for those that require a semi-constrained implant?

METHODS

A multicenter retrospective study was performed to retrospectively review patients that had a Stryker Triathlon (Kalamazoo, MI) TKA with a Total Stabilized (TS) tibial insert (n=75). This TS cohort was subsequently matched 1:1 based on age, gender, and BMI to a cohort of patients with the same primary TKA design with a PS insert (n=75). Preoperative and postoperative radiographic and clinical data were compared between the two groups.

RESULTS

Preoperatively, the TS cohort had significantly greater varus (9.72 vs. 3.48; p=0.0001) and valgus (14.1 vs. 7.57; p=0.0001) deformity. Post-operatively, there were no statistically significant differences in revisions (p=1), reoperations (p=1), or complications (p=1). Mean clinical and radiographic follow-ups were equivalent between groups (25.5 vs. 25.8months, p=0.8851).

CONCLUSION

As suspected, use of a semi-constrained insert to achieve intraoperative coronal stability was most predicted by preoperative coronal deformity (either varus or valgus). Longer follow-up and larger patient cohorts are necessary to determine.

Posterior Femoral Single Limb Osteotomy for the Removal of Well-Fixed Modular Femoral Neck Components

Modular neck femoral components were introduced to optimize femoral neck anteversion, leg length, offset, and stability in total hip arthroplasty. However, concerns have been raised in recent years regarding early failure of these implants due to corrosion, pseudotumor, as well as fracture of the modular neck. Removing modular neck femoral implants is challenging as removal of the modular femoral neck leaves a proximally coated femoral stem level with the proximal bone of the femoral neck. We describe a posterior femoral single limb osteotomy  (posterior cut of an extended trochanteric osteotomy) for the removal of a modular neck femoral component.

Midterm Clinical and Radiographic Results of Mobile-Bearing Revision Total Knee Arthroplasty

BACKGROUND

Constrained implants are frequently required in revision total knee arthroplasty (TKA) and are associated with an increase in aseptic component loosening and damage or wear to the constraining mechanisms, compared with primary TKA. The purpose of the following study was to evaluate the midterm clinical and radiographic results including the incidence of bearing complications in a group of patients undergoing revision TKA using mobile-bearing revision TKA implants.

METHODS

We retrospectively reviewed 316 consecutive mobile-bearing revision TKAs performed at 2 centers between 2006 and 2010. There were 183 women and 133 men with a mean age of 66 years. The patients were evaluated clinically using the Knee Society scores. A radiographic analysis was performed. Bearing specific complications (ie, instability or dislocation) were recorded.

RESULTS

Patients were followed-up for a minimum of 24 months and a median of 59.88 months (range 24-121.2). The average Knee Society knee score and function scores increased from 40.8 and 47.9 points preoperatively to 80 points and 70.3 points, respectively (P < .01). The average knee flexion improved from 105.6° preoperatively to 117.4° postoperatively (P < .01). Eight patients required subsequent implant revision. No cases of bearing complications were observed.

CONCLUSION

Revision TKA using mobile-bearing revision components demonstrated favorable midterm clinical and radiographic results with no occurrence of bearing instability or dislocation. Longer follow-up is required to evaluate for potential advantages of mobile-bearings over fixed-bearing revision components in terms of polyethylene wear reduction, reduced stress transmission across fixation interfaces, and reduced stress on the polyethylene post.

Construct Rigidity: Keystone for Treating Pelvic Discontinuity

BACKGROUND

Pelvic discontinuity is uncommon and presents the surgeon with complex reconstructive challenges. The objective of this study is to report the results of current strategies used in the treatment of pelvic discontinuity.

METHODS

We retrospectively analyzed prospectively collected data on 113 consecutive revision total hip arthroplasties performed for the treatment of unilateral pelvic discontinuity at a single institution. The study included 18 male and 95 female patients with a mean age of 63 years at the time of revision surgery. Preoperative, immediate postoperative, and latest follow-up radiographs were reviewed to assess healing of the discontinuity as well as acetabular component stability. Treatment modalities included an uncemented cup with a posterior column plate (50 hips; 44%), a cup-cage construct (27 hips; 24%), an antiprotrusio cage with or without a posterior column plate (26 hips; 23%), and an uncemented cup alone (10 hips; 9%). The average duration of follow-up for each of these types of surgical reconstruction was similar (range, 3.9 to 7.2 years).

RESULTS

Five-year revision-free survivorship of the implant was best with a cup-cage construct (100%) and worst with an uncemented cup with a posterior column plate (80%) and a cup alone (80%). Healing of the discontinuity was achieved in 50% of the hips with an uncemented cup alone, 74% of the hips with an uncemented cup and a posterior column plate, 74% of the hips with a cup-cage construct, and 88% of the hips with an antiprotrusio cage construct (91% of these hips when structural allograft was used). The overall complication rate was 26.5%. The average Harris hip score improved from 54 preoperatively to 69 postoperatively (95% confidence interval: 50 to 57 preoperatively and 65 to 72 postoperatively; p = 0.017).

CONCLUSIONS

Improved survivorship and healing rates were seen in this series when a reconstruction cage was used as an adjunct to an uncemented cup (cup-cage) or in combination with structural allograft bone that bridged the discontinuity.

LEVEL OF EVIDENCE

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

Medial Tibial Reduction Osteotomy is Associated with Excellent Outcomes and Improved Coronal Alignment

Background: The medial tibial reduction osteotomy (MTRO) was introduced to achieve coronal ligamentous balance in total knee arthroplasty (TKA) patients with substantial preoperative varus deformity. Limited data exists on the outcomes of patients requiring an MTRO. This study compares outcomes of a matched cohort of patients that either required or did not require an MTRO during TKA.Methods: A retrospective review was performed on 67 patients that underwent an MTRO during primary TKA to achieve coronal balance. This patient population was matched 1:1 to another cohort of TKA patients by age, gender, and BMI that did not require an MTRO. A clinical and radiographic evaluation was utilized to compare the two cohorts.Results: Preoperatively, the tibiofemoral angle was 3.42° valgus versus 6.12° varus in the control and MTRO cohorts respectively (p=0.01). Mean postoperative tibiofemoral angles were 3.40° versus 2.43° valgus respectively. Postoperative Knee Society Scores were superior in the MTRO cohort (183.84 versus 174.58; p=0.04). Intraoperatively, no superficial MCL releases were required to achieve coronal balance in either cohort. Complications were similar and limited in both groups.  Medial tibial bone resorption was observed in 64% of MTRO subjects averaging 2.02mm versus only 0.3mm in the control cohort ( p=0.01).Conclusion: Patients requiring an MTRO achieved similar alignment and superior knee scores compared to a control cohort with less varus deformity. This procedure eliminated the need for release of the superficial MCL.  Resorption of medial tibial bone was commonly observed, possibly secondary to saw-induced thermal necrosis associated with performing an MTRO.

Diagnosing and Treating Popliteal Tendinopathy After Total Knee Arthroplasty

The following office tip describes four patients that underwent primary total knee arthroplasty and developed posterolateral knee pain at a mean follow-up duration of 1.6 months postoperatively. The first patient in this series noted substantial pain lying in bed (in a lateral decubitus position with the operative leg up) while attempting to abduct her leg to adjust her sheet in bed. A thorough clinical and radiographic work-up was performed. This patient’s posturing in bed (and subsequent physical exam maneuver) led to a presumptive diagnosis of popliteal tendinopathy. The diagnosis was confirmed arthroscopically by identifying a frayed and inflamed popliteal tendon. After undergoing arthroscopic popliteal tendon release, the patient noted complete pain relief while retaining coronal stability in both flexion and extension. The following office tip defines a previously undescribed clinical diagnostic examination for popliteal tendinopathy that was identified based on a patient’s symptomatology and subsequently utilized to identify three additional cases of arthroscopically confirmed popliteal tendinopathy.

Metal Artifact Reduction Sequence MRI Abnormalities in Asymptomatic Patients with a Ceramic-on-Polyethylene Total Hip Replacement

BACKGROUND

Magnetic resonance imaging (MRI) is a commonly utilized screening modality in patients with a metal-on-metal (MoM) total hip replacement. The prevalence of clinically important fluid collections may be overestimated since these collections have been reported to occur in asymptomatic patients with MoM and other bearing surfaces. The purpose of this study was to determine the frequency and types of MRI-documented adverse local tissue reactions in asymptomatic patients with a ceramic-on-polyethylene (CoP) total hip replacement.

METHODS

Forty-four patients (50 hips) with a minimum 2-year follow-up after total hip arthroplasty with CoP implants and a Harris hip score of >90 were enrolled in this study. The inclusion criteria were the absence of hip pain and the availability of appropriate follow-up radiographs. All patients underwent a metal artifact reduction sequence (MARS) MRI scan to determine the presence of fluid collections in asymptomatic patients with a CoP bearing surface.

RESULTS

Fluid collections were observed in 9 (18%) of 50 asymptomatic hips in this cohort. There were 5 hips with intracapsular synovitis, and 2 of these hips had a thickened synovium. Extra-articular fluid collections with direct intracapsular communication were identified in 4 additional hips. Two of these hips had a thickened synovium. No signs of osteolysis or evidence of adverse local tissue reactions were noted on radiographs at the most recent follow-up.

CONCLUSIONS

This study revealed that fluid collections are not uncommon after total hip arthroplasty with CoP implants. Synovial thickening may be present and is more prevalent than has been reported in previous studies involving metal-on-polyethylene (MoP) bearing surfaces. The clinical importance and natural history of these findings remain unknown.

LEVEL OF EVIDENCE

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

Femoral Implant Design Modification Decreases the Incidence of Patellar Crepitus in Total Knee Arthroplasty

BACKGROUND

Patellar crepitus is a complication most commonly seen in patients implanted with a posterior-stabilized total knee arthroplasty (TKA). Recently, design changes in the patellofemoral geometry and the intercondylar box ratio have been optimized in newer TKA designs. A comparative study was performed to analyze the incidence of patellar crepitus between a historical vs modern TKA design.

METHODS

A retrospective review of all patients at our institution that underwent a primary TKA with either a PFC Sigma or Attune posterior-stabilized TKA (DePuy, Inc, Warsaw, IN), with a minimum of 1-year follow-up duration was performed. A total of 1165 participants implanted with the PFC Sigma and 728 with the Attune design were analyzed. Patellar crepitus incidence, functional scores, and range of motion were recorded at each follow-up appointment. Statistical analyses were performed between the 2 groups to determine if there were differences in clinical outcomes.

RESULTS

The incidence of crepitus in participants implanted with the Attune was 0.55% vs 6.26% in the PFC Sigma cohort (P < .001) at 1 year vs. 0.83% vs 9.4%, respectively at 2 years post operatively (P < .001). There were small differences in extension, flexion, and Knee Society Scores between the 2 groups that were not clinically meaningful.

CONCLUSION

The Attune posterior-stabilized TKA demonstrated substantially less patellofemoral crepitus incidence than the historical control. We hypothesize that these findings are related to femoral component changes including a thinner and narrower anterior flange and a reduced femoral intercondylar box ratio.

What Preoperative Radiographic Parameters Are Associated With Increased Medial Release in Total Knee Arthroplasty?

BACKGROUND

Preoperative varus deformity of the knee is a common malalignment in patients undergoing primary total knee arthroplasty (TKA). We are unaware of any studies that have correlated how various preoperative radiographic parameters can predict the amount of medial releases performed to achieve optimal coronal alignment and ligamentous balance.

METHODS

A retrospective review was performed on 67 patients who required at least a medial tibial reduction osteotomy (MTRO) during primary TKA to achieve coronal balance. This patient population was matched 1:1 to another cohort of TKA patients by age, gender, and body mass index who did not require an MTRO. A radiographic evaluation was used to compare the 2 cohorts.

RESULTS

Preoperatively, the MTRO cohort was noted to have significantly increased varus tibiofemoral (86.12° vs 93.43°), tibial articular surface (85.79° vs 87.54°), and medial tibial articular surface angles (75.22° vs 85.34°) compared to the control cohort. The MTRO cohort had 3.13 mm of medial tibial offset and 9.06 mm of lateral joint space opening and the control cohort had 0.09 mm and 4.07 mm, respectively. The medial tibial articular surface angle and lateral joint space widening were statistically associated with the MTRO cohort. The final tibiofemoral angle in the MTRO cohort was 92.43° and was 93.40° in the control cohort.

CONCLUSION

The MTRO cohort was noted to have several preoperative radiographic parameters that were significantly different than the control cohort. However, the medial tibial articular surface angle and lateral joint space widening were the only radiographic parameters that were statistically associated with requiring an MTRO.

Total Knee Arthroplasty After Anterior Cruciate Ligament Reconstruction: Not Just a Routine Primary Arthroplasty

BACKGROUND

Despite the success of restoring joint stability and improving early functional outcomes after anterior cruciate ligament (ACL) reconstruction, the long-term risk of developing symptomatic osteoarthritis requiring total knee arthroplasty is higher than that in the uninjured population. The purpose of this study was to compare operative characteristics and early outcomes of patients undergoing total knee arthroplasty after ACL reconstruction with those of a matched cohort of control subjects with primary osteoarthritis and no history of ligament reconstruction.

METHODS

All patients who had undergone total knee arthroplasty from 2005 to 2013 at our institution with a history of ACL reconstruction and a minimum 2-year follow-up were identified from a prospective research database. These patients were matched by demographic and surgeon variables to patients who had not undergone prior ACL reconstruction. Outcomes included Knee Society Scores (KSS), range of motion, operative variables, complications, and reoperations.

RESULTS

A cohort of 122 patients was identified as the ACL study group and was compared with the matched control cohort. The mean age at the time of the surgical procedure was 58 years, and 55% of the patients were male. The mean follow-up was 3.3 years in the ACL group and 3.0 years in the control group. There was no significant difference in the latest KSS outcomes between groups postoperatively (p > 0.05). Although preoperative flexion was significantly lower (p = 0.01) in the ACL group (119°) than in the control group (123°), there was no difference between groups postoperatively. Fifty percent (61 of 122) of patients in the ACL group required implant removal at the time of total knee arthroplasty. The operative time was significantly longer (p < 0.001) in the ACL group (88 minutes) compared with the control group (73 minutes). There were a total of 11 reoperations in the ACL group, including 4 for periprosthetic infection, whereas there were only 2 reoperations in the control group. The risk of reoperation in the ACL group was more than 5 times higher than in the control group (relative risk, 5.5 [95% confidence interval, 1.2 to 24.3]; p = 0.01).

CONCLUSIONS

The results of this retrospective matched cohort study suggest that prior ACL reconstruction results in longer operative time and increased risk of early reoperation after total knee arthroplasty.

LEVEL OF EVIDENCE

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

Medial Tibial Stress Shielding: A Limitation of Cobalt Chromium Tibial Baseplates

BACKGROUND

Stress shielding is a well-recognized complication associated with total knee arthroplasty. However, this phenomenon has not been thoroughly described. Specifically, no study to our knowledge has evaluated the radiographic impact of utilizing various tibial component compositions on tibial stress shielding.

METHODS

We retrospectively reviewed 3 cohorts of 50 patients that had a preoperative varus deformity and were implanted with a titanium, cobalt chromium (CoCr), or an all polyethylene tibial implant. A radiographic comparative analysis was performed to evaluate the amount of medial tibial bone loss in each cohort. In addition, a clinical outcomes analysis was performed on the 3 cohorts.

RESULTS

The CoCr was noted to have a statistically significant increase in medial tibial bone loss compared with the other 2 cohorts. The all polyethylene cohort had a statistically significantly higher final Knee Society Score and was associated with the least amount of stress shielding.

CONCLUSION

The CoCr tray is the most rigid of 3 implants that were compared in this study. Interestingly, this cohort had the highest amount of medial tibial bone loss. In addition, 1 patient in the CoCr cohort had medial soft tissue irritation which was attributed to a prominent medial tibial tray which required revision surgery to mitigate the symptoms.

Tibial Tray Thickness Significantly Increases Medial Tibial Bone Resorption in Cobalt-Chromium Total Knee Arthroplasty Implants

BACKGROUND

Stress shielding is an uncommon complication associated with primary total knee arthroplasty. Patients are frequently identified radiographically with minimal clinical symptoms. Very few studies have evaluated risk factors for postoperative medial tibial bone loss. We hypothesized that thicker cobalt-chromium tibial trays are associated with increased bone loss.

METHODS

We performed a retrospective review of 100 posterior stabilized, fixed-bearing total knee arthroplasty where 50 patients had a 4-mm-thick tibial tray (thick tray cohort) and 50 patients had a 2.7-mm-thick tibial tray (thin tray cohort). A clinical evaluation and a radiographic assessment of medial tibial bone loss were performed on both cohorts at a minimum of 2 years postoperatively.

RESULTS

Mean medial tibial bone loss was significantly higher in the thick tray cohort (1.07 vs 0.16 mm; P = .0001). In addition, there were significantly more patients with medial tibial bone loss in the thick tray group compared with the thin tray group (44% vs 10%, P = .0002). Despite these differences, there were no statistically significant differences in range of motion, knee society score, complications, or revision surgeries performed.

CONCLUSION

A thicker cobalt-chromium tray was associated with significantly more medial tibial bone loss. Despite these radiographic findings, we found no discernable differences in clinical outcomes in our patient cohort. Further study and longer follow-up are needed to understand the effects and clinical significance of medial tibial bone loss.

Rotating platform versus fixed bearing total knee arthroplasty at mid-term follow-up

BACKGROUND

Rotating platform posterior stabilized (RP) total knee arthroplasty (TKA) was initially developed in part to decrease polyethylene wear and to improve patellar tracking. There have been limited studies evaluating the longevity and causes of reoperation or revision for this implant. The following study compares mid-term survival rates and causes for reoperation between fixed bearing (FB) TKAs.

METHODS

We identified 11,416 patients who underwent a primary posterior stabilized TKA between 2001 and 2013. This group was stratified to include patients with a RP (n=926) and FB (n=10,490) TKA design. Kaplan-Meier survival rates for each complication that led to reoperation were determined at five- and 10-years. Univariate hazard ratios were determined for the most common causes for reoperation and overall implant survival rates. A multivariate analysis was performed to account for the age, gender and preoperative diagnosis discrepancy between groups.

RESULTS

The reoperation data demonstrated statistically increased all-cause reoperation rate (p=<0.001) and reoperation rate for stiffness in the RP group (p=0.001). After adjusting for demographic variables we noted no statistically significant differences in reoperation rate and reoperation for stiffness. Additionally, a statistically significant decrease was noted in all-cause revision (p=0.024) and revision for aseptic loosening or osteolysis in the RP group (p=0.029).

CONCLUSION

After adjusting for patient demographic differences, we noted a statistically significant decrease in the overall revision and revision for aseptic loosening or osteolysis rates in the RP group.

Abdominal ectopic pregnancy after in vitro fertilization and single embryo transfer: a case report and systematic review

BACKGROUND

Ectopic pregnancy is the leading cause of maternal morbidity and mortality during the first trimester and the incidence increases dramatically with assisted-reproductive technology (ART), occurring in approximately 1.5-2.1 % of patients undergoing in-vitro fertilization (IVF). Abdominal ectopic pregnancy is a rare yet clinically significant form of ectopic pregnancy due to potentially high maternal morbidity. While risk factors for ectopic pregnancy after IVF have been studied, very little is known about risk factors specific for abdominal ectopic pregnancy. We present a case of a 30 year-old woman who had an abdominal ectopic pregnancy following IVF and elective single embryo transfer, which was diagnosed and managed by laparoscopy. We performed a systematic literature search to identify case reports of abdominal or heterotopic abdominal ectopic pregnancies after IVF. A total of 28 cases were identified.

RESULTS

Patients' ages ranged from 23 to 38 (Mean 33.2, S.D. = 3.2). Infertility causes included tubal factor (46 %), endometriosis (14 %), male factor (14 %), pelvic adhesive disease (7 %), structural/DES exposure (7 %), and unexplained infertility (14 %). A history of ectopic pregnancy was identified in 39 % of cases. A history of tubal surgery was identified in 50 % of cases, 32 % cases having had bilateral salpingectomy. Transfer of two embryos or more (79 %) and fresh embryo transfer (71 %) were reported in the majority of cases. Heterotopic abdominal pregnancy occurred in 46 % of cases while 54 % were abdominal ectopic pregnancies.

CONCLUSIONS

Our systematic review has revealed several trends in reported cases of abdominal ectopic pregnancy after IVF including tubal factor infertility, history of tubal ectopic and tubal surgery, higher number of embryos transferred, and fresh embryo transfers. These are consistent with known risk factors for ectopic pregnancy following IVF. Further research focusing on more homogenous population may help in better characterizing this rare IVF complication and its risks.

Complex Primary Total Knee Arthroplasty: Long-Term Outcomes

BACKGROUND

Total knee arthroplasty in patients with severe preoperative deformity, ligamentous instability, and/or marked bone loss occasionally requires a varus and valgus constrained or rotating-hinge design prosthesis. The purpose of this study was to compare patient populations that underwent primary total knee arthroplasty with constrained or unconstrained total knee arthroplasty implants to determine patient demographic characteristics, long-term survival, and reasons for reoperation and revision for each group.

METHODS

We identified 28,667 primary total knee arthroplasties performed from 1979 to 2013 at our institution. A total of 427 knees had a varus and valgus constrained design and 246 knees underwent rotating-hinge total knee arthroplasties. Patient demographic information and preoperative diagnoses were analyzed by implant type. A multivariate analysis was performed to account for age, sex, and body mass index (BMI). Kaplan-Meier survival rates for each complication leading to reoperation or component revision were determined at 10 and 20 years. Adjusted hazard ratios were determined for the most common causes for reoperation and revision compared with a routine total knee arthroplasty control group.

RESULTS

Patient demographic characteristics were significantly different (p < 0.05) between all groups for age, sex, and BMI. The varus and valgus constrained and rotating-hinge groups had decreased survival free of all-cause reoperation at 10 and 20 years compared with the unconstrained total knee arthroplasty group, with a hazard ratio of 1.74 (95% confidence interval [95% CI], 1.36 to 2.23) for the valgus and varus constrained group and 2.07 (95% CI, 1.58 to 2.70) for the rotating-hinge group. The adjusted hazard ratio for all-cause revision was significantly higher for the varus and valgus constrained group at 1.65 (p = 0.007) but not for the rotating-hinge group at 1.48 (p = 0.054) compared with the unconstrained total knee arthroplasty group. Wear and osteolysis, infection, and fracture were the most common reasons for component revision in both groups.

CONCLUSIONS

We found increased reoperation and revision rates associated with the use of constrained implants at the time of index total knee arthroplasty. The rate of component revision for any reason at 10 years was >2 times higher in the constrained total knee arthroplasty groups compared with the unconstrained total knee arthroplasty group. At 20 years postoperatively, the component revision rate was >3 times higher.

LEVEL OF EVIDENCE

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