Hardware Removal and Conversion Hip Arthroplasty via a Single Interval Anterior Approach: Surgical Technique

The supine 'off-table' anterior-based muscle-sparing (ABMS) approach is an established approach for primary total hip arthroplasty. The approach is performed with the patient positioned supine on a regular operating room table. It combines utilizing the Watson-Jones interval (without disrupting the abductor muscles) with principles of capsular management borrowed from the direct anterior approach. The approach may also be utilized for complex primary and revision hip arthroplasties. One clinical scenario the ABMS approach may be particularly well-suited to is conversion hip arthroplasty when retained hardware requires removal. The approach enables the surgeon to remove proximal femoral hardware and perform hip arthroplasty within the same muscle interval. This is in contrast to direct anterior approach, which entails separate windows being created on either side of the tensor fascia lata muscle to remove hardware and insert hip arthroplasty components, respectively. In this article, we describe our surgical technique for performing conversion total hip arthroplasty with hardware removal (sliding hip screw and plate in the discussed case) via a single interval with the supine off-table ABMS approach.

Total Hip Arthroplasty After Proximal Femoral Nailing: Preoperative Preparation and Intraoperative Surgical Techniques

The combination of an aging population and increased utilization of total hip arthroplasty (THA) is leading to a higher incidence of conversion THA, defined as conversion from previous hip fracture surgery to THA. Conversion THA is a more technically challenging, time-consuming, and costly procedure compared to primary THA and frequently involve more medically complex patients. Thus, the aim of this review is to provide a rubric for surgeons to use when preparing for a conversion THA. We have assessed the compatibility of commonly available extraction devices with popular femoral nails. Furthermore, we review technical pearls for conversion THA including equipment planning, operative setup, intraoperative imaging, extraction sequencing, and troubleshooting commonly encountered obstacles.

Outcomes of Total Hip Replacement for Failed Hemiarthroplasty

Aim

Our study aims to analyze the outcomes of conversion total hip replacement (THR) done for failed hemiarthroplasty.

Patients and Methods

We retrospectively analyzed 104 consecutive patients who underwent conversion THR for failed hemiarthroplasty between January 2012 and December 2018. The patient's records were analyzed for demographic information, index surgery details, preoperative functional status, and perioperative complications. Patients were analyzed according to the various modes of failure of hemiarthroplasty. The radiographs were analyzed for any progressive osteolysis, cup migration and stem subsidence. All the patients were evaluated using the modified Harris hip score (HHS) for clinical outcome. Complications, revision or reoperation in the follow-up period was recorded.

Results

A total of 73 patients were included in the study for final analysis after exclusion criteria. The average follow-up was 48.2 ± 29.6 months. There was a significant improvement in mean HHS from 38.5 ± 9.1 preoperatively to 80.9 ± 4.3 at the last follow-up (p < 0.05). The different modes of failure had no statistically significant difference in the postoperative Harris hip score (p = 0.393). None of the patients had progressive radiolucent lines more than 2 mm or significant subsidence in the final follow-up compared to the initial postoperative radiograph. There was one deep infection, one patient had grade 2 heterotopic ossification, intraoperative calcar fracture was fixed with cerclage wiring in 11 patients, and postoperative periprosthetic fracture in two patients was treated with plate osteosynthesis. There were no neurovascular complications or dislocation during the follow-up.

Conclusion

Conversion THR for failed hemiarthroplasty is a challenging procedure and results in good functional outcome and provides reliable pain relief. Conversion THA for septic loosening by two stage revision have comparable postoperative outcomes like THA for aseptic loosening. Caution is required owing to high incidence of peri-prosthetic fracture during conversion THA. Dislocation rate is negligible even with smaller head provided the prosthesis is implanted in the proper orientation and adequate soft tissue balancing is achieved.

Conversion hip arthroplasty for failed internal fixation of ipsilateral femoral neck and shaft fractures: a case report

BACKGROUND

Ipsilateral femoral neck and hip fractures are uncommon high energy injuries. In the literature no single method of treatment has emerged as superior to the others. A recent publication has documented the successful application of the rendezvous technique using dual-implants for treating these injuries. However in some cases, this technique may fail and revision surgery is required.

CASE PRESENTATION

A 67-year old man sustained ipsilateral fractures of his femur and femoral neck in a road traffic accident. His injuries were treated by a dual construct consisting of a retrograde femoral nail and dynamic hip screw. Three months after surgery the hip screw cut out of the femoral head necessitating revision to a total hip arthroplasty. Surgery was carried out using a single stage two part procedure on a standard operating table without having to reposition or redrape the patient. There were no postoperative complications and at 1 year from surgery the patient is satisfied with the result and has returned to work.

CONCLUSION

Conversion hip arthroplasty in the presence of dual implants is a technically challenging and unpredictable procedure, with an increased risk of complications. Our surgical approach provides a framework for orthopedic surgeons to safely perform this complex procedure.

Conversion total hip arthroplasty for early failure following unstable intertrochanteric hip fracture: what can patients expect?

PURPOSE

To report surgical outcomes in patients treated with conversion total hip arthroplasty (CTHA) for early failure of cephalomedullary nails (CMNs).

METHODS

A retrospective review was conducted of CTHA for treatment of failed CMN within 1 year of initial surgery for intertrochanteric (IT) hip fractures. The cohort was matched 1:5 to patients who underwent elective primary THA (PTHA). Patient demographics, mechanism of CMN failure, surgical outcomes, and complication rates were assessed.

RESULTS

22 patients met criteria with a mean time to failure of 145 days. Modes of failure included: lag screw cut-out with superior migration (9, 40.9%), or medialization (8, 36.4%), and aseptic nonunion with implant failure (2, 9.0%) and without implant failure (3, 13.6%). Fourteen of the patients (63.6%) had acetabular-sided damage secondary to lag screw penetration, all in the screw cut-out groups. Patient demographics were similar between cohorts. Compared to PTHA, CTHA patients had increased operative time, blood loss, LOS, and readmission rates. After IMN failure, the operative leg was shorter than the contralateral leg in all cases. CTHA restored leg lengths to <  = 10 mm in 15 (68.1%) of patients, with an average leg length discrepancy after CTHA of 6.7 mm. CTHA patients had increased rates of overall surgical complications and medical complications, specifically anemia (all p < 0.01). Tranexamic acid was used less often in the CTHA group (p < 0.01). Rate of periprosthetic joint infection (PJI), dislocation, and revision were all higher in the CTHA, though did not reach statistical significance.

CONCLUSION

The majority (77.3%) of CMN implant failure for nonunion within 1 year was due to screw cut-out. CTHA is a salvage option for early failed IT hip fracture repair, but expected surgical outcomes are more similar to revision THA than primary THA, with increased risk of readmission, longer surgery and LOS, increased blood loss, and higher complication rates.

LEVEL OF EVIDENCE

III, Retrospective comparative study.

Functional outcome of conversion total hip arthroplasty (CTHA) using uncemented distally loading femoral stem for failed fixation of proximal femoral nail - A case series

Introduction and aims

There is paucity of prospective studies on conversion total hip arthroplasty (CTHA) for failed proximal femoral nailing. The objective of this study is to evaluate the functional outcome of CTHA using extensively porous coated distal loading stem for failed proximal femoral nailing.

Patients and methods

Fifteen consecutively operated patients for failed proximal femoral nail treated with single stage procedure of nail extraction and CTHA were included in this prospective observational study. All patients received metal-on-polyethylene bearing with uncemented press-fit acetabular cup (Pinnacle cup; DePuy, Warsaw [IN], USA) and extensively porous coated distally loading revision stem (Solution stem; DePuy, Warsaw [IN], USA). All patients were assessed preoperatively and postoperatively at one, three, six and more than twelve months using the Harris Hip Score (HHS). The responsiveness of HHS was assessed using Effect Size (ES) and Standardised Response Mean (SRM). ES and SRM >0.8 indicates adequate responsiveness.

Results

The mean duration of follow-up was 16.9 months for the overall cohort (SD: 7.9; range: 6-28 months). The mean preoperative HHS was 32 ± 6.1, the mean HHS at six months follow-up was 89.7 ± 4.0 and the mean HHS at final follow-up of atleast one year was 93.7 ± 3.0. There was a statistically and clinically significant improvement in the HHS from preoperatively to final follow-up postoperatively (p < 0.0001). At the final follow-up, twelve patients (80%) had an excellent outcome and three patients (20%) had a good outcome as per HHS grading. The ES was 9.87 and the SRM was 8.86 thereby suggesting adequate responsiveness. One patient developed surgical site infection and another patient developed dislocation. Both were successfully treated and subsequently the patients made uneventful recovery. None of the patients required revision surgery.

Conclusion

HHS has adequate responsiveness for assessing the functional outcome of CTHA. We recommend the use of an uncemented cup and uncemented extensively porous coated, distal loading stem for failed PFN fixation in intertrochanteric hip fractures.

Conversion total hip arthroplasty following extracapsular hip fracture fixation with a cephalomedullary device: a comprehensive review

With the annual incidence of hip fractures and hip fracture fixation rising, the need for conversion total hip arthroplasty has also risen. About half of the 280,000 hip fractures that occur annually in the United States are extracapsular. Commonly extracapsular hip fractures are treated with either cephalomedullary nails (CMNs) or sliding hip screws (SHS). More recently, there has been a shift toward increased CMN use due to increased training with this fixation method as well as perioperative and biomechanical benefits. Given this shift, orthopedic surgeons need to understand the factors that lead to CMN failure. Failed CMN treatment leaves both patients and surgeons with few management options including revision fixation with or without osteotomy, conversion total hip arthroplasty, and conversion hemiarthroplasty. Surgeons must consider the patient and injury characteristics before deciding the best treatment plan. Conversion total hip arthroplasty is indicated in younger patients without femoral head and/or acetabular articular injury, degenerative joint disease, or avascular necrosis. Conversion total arthroplasty is a technically demanding and resource-intensive surgery associated with lower success rates and outcomes than primary total hip arthroplasty. Orthopedic surgeons should have thorough understanding of preoperative workup needed prior to surgery, implant selection associated with best outcomes, most common surgical approaches used, intraoperative considerations, and complications associated with conversion total hip arthroplasty. A comprehensive understanding of these concepts gives patients the best chance of having a successful outcome.

Conversion hip arthroplasty via the direct anterior approach: pearls, pitfalls and personal experience

OBJECTIVE

Conversion total hip arthroplasty (CTHA) through a direct anterior approach (DAA) in supine position.

INDICATIONS

Failed osteosynthesis of proximal femoral fractures or failed conservative hip surgery, with hardware in situ.

CONTRAINDICATIONS

Decayed general conditions, infection (peri-implant or systemic infection), need for greater trochanter reconstruction, severe proximal femur deformity.

SURGICAL TECHNIQUE

Supine position. Mark DAA and expected limited incisions for hardware removal (HR) with the help of a C-arm. Use guidewire and extraction devices for HR. Perform a DAA with particular attention to a wide release of the femur.

POSTOPERATIVE MANAGEMENT

Full progressive weight-bearing starting on day 1, depending on bone quality. Discharge with crutches following patient walking capability. Precautions for 6 weeks.

RESULTS

In all, 27 conversion THAs through a DAA. Mean age at the time of surgery 59.8 (range 18-81) years. Mean body mass index was 23.5 (range 17-31.6). Reasons of previous surgery failures were avascular necrosis of the femoral head, posttraumatic arthritis and nonunion with or without hardware migration. Mean surgical time was 125.8 min (range 58-190 min, standard deviation [SD] 38.2 min). Mean follow-up time was 6.9 years (range 2-15, SD 5.03 years). Mean pre-Harris Hip Score (mHHs) was 24.4 (range 19-36, SD 5.4), while the mean post-mHHS was 90.3 (range 89-91, SD 0.95). Two patients required postoperative osteosynthesis for periprosthetic fractures due to falls. Overall complication rate was 10%.

The Screening of Fixation-Related Infection in Patients Undergoing Conversion Total Hip Arthroplasty after Failed Internal Fixation of Hip Fractures: A Single-Central Retrospective Study

Objective

To evaluate the diagnostic values of preoperative plasma fibrinogen and platelet count for screening fixation‐related infection (FRI) in patients undergoing conversion total hip arthroplasty (cTHA) after failed internal fixation of hip fractures.

Method

This was a single‐center retrospective study. Data were retrospectively analyzed for 435 patients who underwent cTHA in our hospital from January 2008 to September 2020. They were divided into infected (n = 30) and non‐infected groups (n = 405) according to the 2013 International Consensus Meeting (ICM) criteria. The diagnostic sensitivity and specificity of plasma fibrinogen and platelet count were determined using receiver operating characteristic (ROC) curves. Optimal predictive cutoffs of these two markers were determined based on the Youden index. In addition, the diagnostic value of preoperative serum C‐reactive protein (CRP) and erythrocyte sedimentation rate (ESR) for screening FRI were also evaluated based on the cutoffs recommended by the 2013 ICM Criteria. Finally, the diagnostic ability of various combinations of the plasma fibrinogen and platelet count as well as serum CRP and ESR was re‐assessed.

Results

The numbers of patients with and without FRI were 30 (6.9%) and 405 (93.1%), respectively. Areas under the ROC curves were 0.770 for fibrinogen, 0.606 for platelet, 0.844 for CRP and 0.749 for ESR. The optimal predictive cutoff of fibrinogen was 3.73 g/L, which gave sensitivity of 60.0% and specificity of 90.5%. The optimal predictive cutoff for platelet was 241.5 × 10⁹/L, which gave sensitivity of 46.7% and specificity of 83.7%. The CRP gave sensitivity of 66.7% and specificity of 92.5% with the predetermined cutoff of 10 mg/L, while the ESR gave sensitivity of 67.5% and specificity of 72.4% % with the predetermined cutoff of 30 mm/h. The combination of CRP and ESR showed high specificity of 93.2% but low sensitivity of 66.7%, while the corresponding values for CRP with fibrinogen were satisfied both for sensitivity of 80.0% and specificity of 78.7%. The combination of these four biomarkers gave sensitivity of 73.3% and specificity of 85.7%.

Conclusion

Preoperative serum CRP, ESR, plasma fibrinogen and platelet count have low sensitivity on their own for screening FRI in patients, but the combination of CRP with fibrinogen shows promise for that.

Outcome and technical consideration of conversion total hip arthroplasty after failed fixation of intracapsular and extracapsular hip fractures: Are they really that different?

INTRODUCTION

Conversion Total Hip Arthroplasty (cTHA) is a rescue strategy for proximal femur osteosynthesis failures. However, it is unclear whether cTHAs performed for extra-capsular fracture fixation failures (ECF) or for intra-capsular fracture fixation failures (ICF) share the same complexity and efficacy. The purpose of our study was to compare cTHAs performed on pre-existing ICFs and pre-existing ECFs, focusing on surgical complications and functional outcomes in both groups.

METHODS

An observational retrospective study was conducted on cTHA patients, treated between 2014 and 2018, divided into 2 groups: ICF-group and ECF-group. The main outcomes were: type of implant used, duration of surgery, need for transfusions, incidence of complications, functional outcomes.

RESULTS

28 patients were included (15 in the ECF group and 13 in the ICF group); the average follow-up was of 31 ± 17.3 months. No significant differences were identified in terms of the type of implant used and duration of surgery. The number of transfused patients was 4 in the ICF group and 12 in the ECF group (p = 0.02); the average transfused units were 0.4 ± 0.7 in the ICF group and 1.3 ± 0.9 in the ECF group (p = 0.01). The incidence of complications - an infection and a dislocation, both of which occurred in the ICF group - and functional outcomes did not present significant differences.

CONCLUSION

The conversion surgery on ECFs patients is technically more difficult for the surgeon and prone to greater blood loss. The outcomes are satisfactory and overlap between the two groups.

The fate of positive intraoperative cultures following conversion total hip arthroplasty

INTRODUCTION

The objectives of this study are to report the rates of positive intraoperative cultures obtained during conversion total hip arthroplasty (THA) according to index surgery, and to describe the natural history of treatment for a consecutive series of patients with unexpected positive intraoperative cultures during conversion THA.

METHODS

We reviewed all patients at 2 institutions undergoing conversion THA from prior open reduction and internal fixation (ORIF) of acetabular and hip fractures or hemiarthroplasty for displaced femoral neck fractures from 2011 to 2018. Intraoperative cultures were taken in 105 patients. Positive intraoperative cultures during conversion were recorded and managed with an infectious diseases consult. The outcomes including PJI at 90 days and 1 year follow-up were documented.

RESULTS

Overall, 19 of 105 patients (18%) undergoing conversion THA had positive intraoperative cultures, with the highest rates in the hemiarthroplasty 7/16 (44%) and acetabular ORIF 9/48 (19%) groups. All 19 patients were initially treated conservatively: 8 received IV antibiotics, 10 received no additional therapy, and 1 received oral antibiotics. 4/9 acetabular fracture conversions developed PJI at 1 year, with 3 requiring multiple irrigation and debridement/polyethylene exchanges to control the infection while the 4th patient required 2-stage exchange. There were no 1-year PJI from any of the other index procedures after conversion. All 7 hemiarthroplasty patients with positive cultures were treated to resolution with 4-8 weeks IV antibiotics alone.

CONCLUSIONS

Patients undergoing conversion THA from prior hip or acetabular fracture have a high rate of positive intraoperative cultures. As such, all patients undergoing conversion THA from prior hip or acetabular fracture fixation should undergo thorough diagnostic workup prior to surgery, and have intraoperative cultures obtained during surgery if infection remains suspicious. Further work should be performed to develop MSIS criteria for preoperative management of patients undergoing conversion THA.

Is implant sonication useful when screening for infection in conversion of prior hip fracture fixation to total hip arthroplasty?

Objective

To examine sonication results in presumed aseptic conversion total hip arthroplasty (THA) after hip fracture fixation and to evaluate its implications on the treatment outcome.

Methods

This retrospective cohort study reviewed the data from presumed aseptic patients that underwent conversion of prior internal fixation of proximal femoral fractures to THA between 2012 and 2018. Microbiological analysis was performed using sonication of osteosynthesis material and tissue samples. Treatment outcome including the occurrence of periprosthetic joint infection (PJI) was recorded.

Results

A total of 32 patients were included in the study. Of these, five patients (15.6%) had positive intraoperative cultures. The mean follow-up following conversion THA was 43.0 months (range, 19.0–91.5 months). Sonication was positive in three patients (9.4%), all of whom were deemed contaminated and did not develop PJI. Tissue cultures were positive in two patients (6.3%). One patient with Enterococcus faecalis received antibiotic treatment and did not develop PJI. Another patient with growth of Cutibacterium acnes that was initially classified as a contaminant later developed acute PJI caused by the same pathogen. Overall, PJI occurred in two patients (6.3%) after conversion THA.

Conclusion

Sonication of internal fixation devices did not add diagnostic value in clinically aseptic conversion THA. Further studies are needed to better understand the relevance of unexpected positive cultures, and to develop diagnostic criteria for the management of these patients.

Combination of CRP with NLR is a sensitive tool for screening fixation-related infection in patients undergoing conversion total hip arthroplasty after failed internal fixation for femoral neck fracture

AIMS

Monocyte-lymphocyte ratio (MLR) or neutrophil-lymphocyte ratio (NLR) are useful for diagnosing periprosthetic joint infection (PJI), but their diagnostic values are unclear for screening fixation-related infection (FRI) in patients for whom conversion total hip arthroplasty (THA) is planned after failed internal fixation for femoral neck fracture.

METHODS

We retrospectively included 340 patients who underwent conversion THA after internal fixation for femoral neck fracture from January 2008 to September 2020. Those patients constituted two groups: noninfected patients and patients diagnosed with FRI according to the 2013 International Consensus Meeting Criteria. Receiver operating characteristic (ROC) curves were used to determine maximum sensitivity and specificity of these two preoperative ratios. The diagnostic performance of the two ratios combined with preoperative CRP or ESR was also evaluated.

RESULTS

The numbers of patients with and without FRI were 19 (5.6%) and 321 (94.4%), respectively. Areas under the ROC curve for diagnosing FRI were 0.763 for MLR, 0.686 for NLR, 0.905 for CRP, and 0.769 for ESR. Based on the Youden index, the optimal predictive cutoffs were 0.25 for MLR and 2.38 for NLR. Sensitivity and specificity were 78.9% and 71.0% for MLR, and 78.9% and 56.4% for NLR, respectively. The combination of CRP with MLR showed a sensitivity of 84.2% and specificity of 94.6%, while the corresponding values for the combination of CRP with NLR were 89.5% and 91.5%, respectively.

CONCLUSION

The presence of preoperative FRI among patients undergoing conversion THA after internal fixation for femoral neck fracture should be determined. The combination of preoperative CRP with NLR is sensitive tool for screening FRI in those patients. Cite this article: Bone Joint J 2021;103-B(9):1534-1540.

Total hip arthroplasty following failure of tantalum rod implantation for osteonecrosis of the femoral head with 5- to 10-year follow-up

BACKGROUND

Total hip arthroplasty (THA) with failure of tantalum rod implant for osteonecrosis of the femoral head (ONFH) will be the only choice for patients. However,it remains unknown whether tantalum rod implantation has an adverse effect on the survival time of implants following conversion to THA. The aim of this study was to retrospectively evaluate the clinical and radiographic outcomes of conversion to THA in patients who were previously treated with implantation of a tantalum rod.

METHODS

This study included 31 patients (39 hips), who underwent conversion to THA due to failure of core decompression with an implanted tantalum rod. Among these 31 patients, 26 patients were male and five patients were female. The mean age of these patients was 49.3 years old (range: 36-64 years old). The control group included 33 patients (40 hips), who underwent total hip replacement without tantalum rod implantation. The hip Harris score, implant wear, osteolysis, radiolucencies and surgical complications were recorded during the follow-up. The distribution of tantalum debris in the proximal, middle and distal periprosthetic femoral regions, radiolucent lines and osteolysis were analyzed on post-operative radiographs.

RESULTS

There were no significant differences in Harris score, liner wear and complications between the two groups (P > 0.05). Osteolysis and radiolucent lines more likely occurred in patients with tantalum debris distributed in three regions than in one or two regions (P < 0.05).

CONCLUSIONS

The mid-term clinical outcome of patients who underwent THA with tantalum rod implantation was not different from those without a tantalum rod, suggesting that tantalum debris did not increase the liner wear rate. However, the distribution of periprosthetic tantalum debris in the proximal, middle and distal femoral regions may increase the risk of femoral osteolysis and radiolucent lines.

Long-term outcomes of transtrochanteric rotational osteotomy for non-traumatic osteonecrosis of the femoral head

AIMS

Transtrochanteric rotational osteotomy (TRO) is performed for young patients with non-traumatic osteonecrosis of the femoral head (ONFH) to preserve the hip. We aimed to investigate the long-term outcomes and the risk factors for failure 15 years after this procedure.

PATIENTS AND METHODS

This study included 95 patients (111 hips) with a mean age of 40 years (21 to 64) who underwent TRO for ONFH. The mean follow-up was 18.2 years (3 to 26). Kaplan-Meier survivorship analyses were performed with conversion to total hip arthroplasty (THA) and radiological failure due to secondary collapse of the femoral head or osteoarthritic changes as the endpoint. Multivariate analyses were performed to assess risk factors for each outcome.

RESULTS

Survival rates at 15 years with conversion to THA and radiological failure as the endpoint were 59% (95% confidence interval (CI) 49 to 67) and 30% (95% CI 22 to 39), respectively. Necrotic type C2 ONFH (lesions extending laterally to the acetabular edge) (hazards ratio (HR) 3.9) and age > 40 years (HR 2.5) were risk factors for conversion to THA. Stage > 3a ONFH (HR 2.0) and age > 40 years (HR 1.9) were risk factors for radiological failure.

CONCLUSION

The 15 year outcomes after TRO for ONFH are unfavorable because osteoarthritic changes occur after five years post-operatively. Cite this article: Bone Joint J 2017;99-B:175-83.

Conversion total hip arthroplasty: Primary or revision total hip arthroplasty

Total hip arthroplasty (THA) is an increasingly common procedure among elderly individuals. Although conversion THA is currently bundled in a diagnosis related group (DRG) with primary THA, there is a lack of literature supporting this classification and it has yet to be identified whether conversion THA better resembles primary or revision THA. This editorial analyzed the intraoperative and postoperative factors and functional outcomes following conversion THA, primary THA, and revision THA to understand whether the characteristics of conversion THA resemble one procedure or the other, or are possibly somewhere in between. The analysis revealed that conversion THA requires more resources both intraoperatively and postoperatively than primary THA. Furthermore, patients undergoing conversion THA present with poorer functional outcomes in the long run. Patients undergoing conversion THA better resemble revision THA patients than primary THA patients. As such, patients undergoing conversion THA should not be likened to patients undergoing primary THA when determining risk stratification and reimbursement rates. Conversion THA procedures should be planned accordingly with proper anticipation of the greater needs both in the operating room, and for in-patient and follow-up care. We suggest that conversion THA be reclassified in the same DRG with revision THA as opposed to primary THA as a step towards better allocation of healthcare resources for conversion hip arthroplasties.