Incidence of Heterotopic Ossification in Direct Anterior Total Hip Arthroplasty: A Retrospective Radiographic Review

    Incidence of Heterotopic Ossification in Direct Anterior Total Hip Arthroplasty: A Retrospective Radiographic Review Duane M. Tippets DO, Anton Zaryanov DO, W. Vincent Burke MD, Preetesh D. Patel MD, Juan C. Suarez MD, Erin E. Ely MD, Nathania M. Figueroa MD PII: DOI: Reference:

S0883-5403(14)00285-X doi: 10.1016/j.arth.2014.04.027 YARTH 53952

To appear in:

Journal of Arthroplasty

Received date: Revised date: Accepted date:

11 March 2013 1 April 2014 20 April 2014

Please cite this article as: Tippets Duane M., Zaryanov Anton, Vincent Burke W, Patel Preetesh D., Suarez Juan C., Ely Erin E., Figueroa Nathania M., Incidence of Heterotopic Ossification in Direct Anterior Total Hip Arthroplasty: A Retrospective Radiographic Review, Journal of Arthroplasty (2014), doi: 10.1016/j.arth.2014.04.027

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ACCEPTED MANUSCRIPT Incidence of Heterotopic Ossification in Direct Anterior Total Hip Arthroplasty: A

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Retrospective Radiographic Review

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Duane M. Tippets DO*, Anton Zaryanov DOa, W. Vincent Burke MDa, Preetesh D. Patel MD*, Juan C. Suarez MD*, Erin E. Ely MD*, Nathania M. Figueroa MD*

Corresponding Author:

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Juan C. Suarez, MD 2950 Cleveland Clinic Boulevard Weston, FL 33331 (954) 659-5430 [email protected]

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*Cleveland Clinic Florida, Weston, FL a Broward Health Medical Center, Ft. Lauderdale, FL

ACCEPTED MANUSCRIPT Abstract Heterotopic ossification (HO) is a complication following total hip arthroplasty (THA)

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with traditional approaches. The direct anterior approach (DAA) has become a popular

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approach for THA; however, no study has evaluated HO formation following DAA THA. We examined the incidence of HO in a consecutive series of THA using the DAA in two

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separate hospitals. Standard preoperative radiographs were examined to determine the

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type of degenerative arthritis, and follow-up radiographs of at least 6 months after surgery were evaluated for the presence and classification of HO. The overall incidence

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of HO after DAA THA in this study was 98/236, or 41.5%, which falls within the

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reported range from recent studies involving more traditional approaches to the hip.

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Introduction

The direct anterior approach (DAA) has become a more popular approach for total hip

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arthroplasty (THA) in recent years1,2. It is an inter-muscular and inter-nervous approach

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without muscle transection1,3-5. The DAA has shown decreased soft tissue trauma, early recovery of hip function and gait mechanics, lower dislocation rates, and improved shortterm outcomes as compared to the more traditional approaches in THA6-8. Heterotopic ossification (HO) is a frequent complication following THA using traditional approaches, with an incidence of 28-61%9-16. The exact etiology of HO is unknown, but some believe it is the result of osteoinductive growth factors released by the body when soft tissues are traumatized13,17. HO is usually evident on radiographs by 6 weeks after surgery. The ossification matures throughout the first 6 months and then generally does not develop further thereafter18,19. The development of HO is usually

ACCEPTED MANUSCRIPT clinically insignificant; however, the small percentage of patients who develop severe HO may experience decreased hip range of motion and function19,20.

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As the DAA is believed to cause less soft tissue trauma during surgery, we

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hypothesized that patients receiving a THA through this approach would develop less HO when compared to other traditional approaches (e.g. posterior, direct lateral,

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transtrochanteric). The purpose of this study was to determine the incidence of HO in all

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patients who have undergone DAA THA in 2 separate institutions.

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Materials and Methods

The present study was approved by the institutional review boards at both of the hospitals

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involved in the investigation. This retrospective radiographic review assessed the

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incidence of HO in a consecutive series of patients who underwent DAA THA at 2 different institutions between March of 2009 and September of 2011 and had at least 6

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months of follow-up. Two hundred forty-nine hips were identified; however 13 of the

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hips were excluded, leaving 236 hips in 214 patients (n=109 from hospital 1 and n = 127 from hospital 2). Exclusion criteria included infection, HO prophylaxis, or prolonged immobilization, including: 2 in the same patient who received postoperative indomethacin due to his extensive hypertrophic arthritis, 1 hip in a patient complicated by myocardial infarction on postoperative day 1 and prolonged immobilization in the intensive care unit, 1 hip had preoperative radiation for HO prophylaxis due to hypertrophic arthritis, 1 hip dislocated and required revision surgery, 2 hips due to infection, and 1 hip underwent femoral resurfacing.

ACCEPTED MANUSCRIPT The primary surgeons in hospital 1 were 2 fellowship-trained adult reconstruction surgeons who performed the DAA THA on an OSI Hana table (Mizuho Osi, Union City,

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CA).All prostheses were noncemented, a medium hemovac drain was used for the first 24

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hours, and all patients were full weightbearing. These patients received either Aspirin 325 mg by mouth twice a day for 6 weeks or Lovenox (enoxaparin) 40 mg

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subcutaneously daily for 2 weeks for postoperative deep venous thrombosis (DVT)

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prophylaxis. The primary surgeon in hospital 2 was also a fellowship-trained adult reconstruction surgeon who performed DAA THA on a regular operating room table. All

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implanted prostheses were noncemented and all patients were full weightbearing, but a hemovac drain was not utilized. His patients received Coumadin (warfarin) for

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postoperative DVT prophylaxis for 4 weeks with a target international normalized ratio

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(INR) range of 2-3. None of the patients included in the study received any form of HO prophylaxis, which is the standard at both institutions. Only 3-7% of patients who

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develop HO experience clinically significant HO and the two most common prophylactic

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modalities are not without significant side effects21. The surgical dissection for a direct anterior, intermuscular approach (modified Heuter interval) is similar for table and table-less surgery. The incision starts 2-3 cm lateral and 2 cm distal to the anterior superior iliac spine (ASIS). The straight incision extends distally and slightly posteriorly for 10-12 cm. The fascia of the tensor muscle is identified and incised over the muscle belly in its midportion. The fascia is elevated from the muscle fibers medially and the tensor is retracted laterally, while the sartorius and rectus femoris are retracted medially to reveal the Smith-Petersen interval. The lateral circumflex vessels are identified, clamped, and cauterized. Further distal splitting occurs

ACCEPTED MANUSCRIPT through the precapsular fat pad, revealing the anterior capsule. An anterior capsulectomy is done, exposing the femoral neck for an in-situ osteotomy and subsequent acetabular

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debridement, reaming, and implantation. Proximal femoral mobility is achieved by

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releasing the dorso-lateral capsular attachment off the greater trochanter, thereby facilitating a manual elevation of the femur anterior and lateral to the posterior acetabular

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rim. If necessary, releases of the insertions of the short external rotator tendons or the

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origin of the tensor muscle can be performed for further elevation and/or exposure prior to femoral broaching and stem implantation.

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The predominant differences between table and table-less surgery lie outside the surgical field. During proximal femoral elevation, a table hook is utilized around the

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posterior femur to aid in mobility while the spar of the table is lowered to aid in hip

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hyperextension, external rotation, and adduction. In table-less surgery, following femoral releases, the leg part of the table is lowered 30-50 degrees for hip hyperextension and a

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femoral retractor is placed behind the greater trochanter to manually elevate the femur.

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Hip adduction and external rotation is manually achieved by an assistant. Demographic data from chart review were obtained, which included patient age, sex, body mass index, and type of DVT prophylactic agent received. Preoperative radiographs including anteroposterior (AP) and frog lateral views of the hip were reviewed for each patient and the type of arthritis was classified as either hypertrophic, atrophic (Figure 1), or normotrophic based on the Bomebelli classification22. This includes Class 1: islands of bone within the soft tissues of the hip; Class 2: bone spurs from the pelvis or proximal end of the femur, leaving at least 1 cm between opposing bone surfaces; Class 3: bone spurs from the pelvis or proximal end of the femur,

ACCEPTED MANUSCRIPT reducing the space between opposing bone surfaces to less than 1 cm; and Class 4: apparent bone ankylosis of the hip6. The minimum follow-up of 6 months was chosen

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because HO is believed to mature by 6 months and not develop further thereafter6,10,19.

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All radiographs were independently reviewed and classified by 2 separate investigators, 1 from each institution. Logistic regression was used to determine relative risk associated

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with hospital, gender, and use of DVT prophylaxis. The chi-square test was used to

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analyze the type of arthritis and linear regression was used to look at age and BMI. A Mann Whitney U test was performed to compare the Brooker scores between the two

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hospitals.

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Results

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The initial study population included 249 hips, while the final study population included 236 hips in 214 patients. A total of 123 hips were implanted in males and 113 in females.

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The gender distribution was similar between the two hospitals, with 51 hips implanted in

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females and 58 implanted in males in hospital 1 and 62 hips implanted in females and 65 implanted in males in hospital 2. The average age of the patients in the study was 62.6 years (range 29-91). The mean BMI of the study population was 27.6  4.4 (range 17.347.6). For the 236 hips included in the study, the primary diagnoses included osteoarthritis (n=196), avascular necrosis (n=29), developmental dysplasia of the hip (n=3), Legg-Calve-Perthes (n=2), post-traumatic arthritis (n=1), and rheumatoid arthritis (n=1). The overall incidence of HO after DAA THA in this study was 98/236, or 41.5%. In hospital 1, 36/109 (33%) of the patients developed HO, compared with 62/127 (48.8%)

ACCEPTED MANUSCRIPT of the patients in hospital 2 (Table 1). The average incidence of HO between both of the hospitals according to the Brooker classification included class 0 with 62.1%, class 1

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with 21.2%, class 2 with 7.4%, class 3 (Figure 2) with 8.1%, and class 4 with 1.3%. The

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Mann Whitney U test showed statistically significant results when comparing the Brooker scores at the two hospitals, with higher Brooker scores in hospital 2.

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The crude incidence rates of HO and relative risks for different exposures

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revealed that there were significantly more male patients who developed HO (60/123), 48.8%) than females (38/113, 33.6%), (RR 0.62, p=0.02) (Table 1). There also appeared

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to be a tendency for increased HO formation in older age groups (46/97, 47.4% in >65 years), but the results did not reach statistical significance.

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There was no statistical difference in the formation of HO between the different

classification (p=0.53).

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BMI groups (p=0.18), or the different types of arthritis according to the Bombelli

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There was a significant reduction in the risk of HO formation in the patients who

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took aspirin (RR 0.53, p=0.001) compared to the patients who took Coumadin (RR 1.35, p=0.52) or Lovenox (RR 1.20, p=0.33) for DVT prophylaxis.

Discussion Heterotopic ossification is a common complication following THA. While the exact mechanism of the formation is unknown, one theory suggests that it is the result of displacement of osteoprogenitor cells from the femoral canal during the reaming and broaching process. These cells are placed directly into a well-vascularized muscle site

ACCEPTED MANUSCRIPT among osteoinductive growth factors that have been released from the traumatized tissues. These factors may then induce these cells into bone development17.

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Some believe that the osteoinductive cells are derived mainly from the soft tissues

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and not from the bone. Pellegrini and Gregoritz23 conducted a study which gave support to this theory. They showed that a single 8-gray fraction of radiation directed only at the

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soft tissues where HO develops and not at the bone significantly decreased the incidence

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of postoperative HO after THA. A study by Sneath et al.13 also supported this theory. They compared the amount of HO formed after THA in patients who received 3 liters of

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pulsatile lavage versus patients who only received 500 mls of irrigation from a bulb syringe. They assumed that if the bone forming cells came from the femoral canal, then

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the patients who received the pulsatile lavage would have less HO. Their study showed

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no significant difference between the two groups, which added support to the idea that these bone forming cells may indeed come from the traumatized soft tissues.

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One of the reasons that the direct anterior approach to THA has recently become

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more popular is that it utilizes an intermuscular approach, which minimizes trauma to the soft tissues. This was confirmed by Bergin et al.6 who demonstrated significantly decreased serum CK levels postoperatively in patients undergoing DAA THA compared to patients who had a posterolateral approach. Meneghini et al.5 also demonstrated significantly less visible muscle damage after a DAA THA approach when compared to a minimally invasive posterior approach in cadavers. Based on the evidence of less soft tissue damage with the anterior approach, we hypothesized that the DAA THA would have a decreased incidence of HO when compared to other traditional approaches in THA. However, the incidence of HO in

ACCEPTED MANUSCRIPT patients undergoing DAA THA in this study was 41.5%, with 9.4% being severe (Brooker class 3 and 4). This fell within the reported incidence range of 28-61%, with

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3.3-14% severe, found in recent studies evaluating HO after posterior, direct lateral, and

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transtrochanteric approaches9-16.

In our study, we found an increased incidence of HO associated with the male

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gender, which has likewise been found in other studies11,15,19. We did not find an

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increased incidence of HO among patients with preoperative hypertrophic osteoarthritis, which has also been reported in other similar studies9,15,16. However, many other studies

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have found a significant increase in the incidence of HO in this group of patients11-13,19. A major differentiator between the two hospitals was DVT prophylaxis. We

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found a significant reduction in the risk of HO formation among patients who took

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aspirin (hospital 1; RR 1.35, p=0.001, 19/74, 25.7%) compared to those who took Coumadin (hospital 2; RR 1.35, p=0.52, 58/122, 47.5%) for DVT prophylaxis. This was

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similar to the findings of Cohn et al.24, who found an 11% incidence of HO among

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patients on aspirin compared to 34.2% in patients on Coumadin. Additionally, Beck et al.25 found a 32.5% incidence in patients on aspirin and a 60.4% incidence in patients on Coumadin.

An interesting result was found in our study following a logistic regression analysis. The analysis was conducted to estimate the adjusted association of all the patient variables considered with the formation of HO. All of the variables were adjusted for possible confounding effects. We saw that aspirin and the female gender showed a statistically significant protective association against the formation of HO, and that hospital 2 was statistically significant as a risk factor for HO formation.

ACCEPTED MANUSCRIPT Aside from all the variables included in the logistic regression analysis, one significant difference between the two hospitals was that hospital 1 performed the

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procedures on an OSI Hana table, while hospital 2 performed them on a regular OR table.

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The OSI Hana table uses a mechanical lift in conjunction with a bone hook placed behind the proximal femur to lift the femoral canal from the wound to facilitate canal

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preparation. Without the table OSI Hana table, instruments such as a femoral elevator

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must be driven under the greater trochanter to forcefully lever the proximal femur out of the wound without the aid of a mechanical lift. Perhaps this causes more soft tissue

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trauma to the abductors and thus more HO formation. Additionally, hospital 1 used a single femoral neck cut and a hemovac drain compared to the double femoral neck cut

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and no drain used by hospital 2. Perhaps these influenced the development of HO.

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Neither hospital currently utilizes HO prophylaxis at this time due to the fact that the side effects of prophylaxis outweigh the risk of development. As this study was only a

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retrospective radiographic review, further prospective studies would be needed to explore

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any correlation of the type of surgical table and technique, DVT prophylaxis, and drain used with the formation of HO. In conclusion, despite the benefits of decreased soft tissue trauma, early recovery of hip function, and low dislocation rates associated with the DAA THA, this study did not show a decreased incidence of HO with this approach when compared to other approaches in the recent literature. Further studies will be needed to determine if certain variables, such as the type of surgical table utilized, may lead to an increased incidence of HO among patients undergoing DAA THA.

ACCEPTED MANUSCRIPT References 1. Matta JM, Shahrdar C, Ferguson T. Single-incision anterior approach for total hip

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arthroplasty on an orthopaedic table. Clin Orthop Rel Res. 2005;441:115-24.

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2. Rachbauer F, Kain MS, Leunig M. The history of the anterior approach to the hip. Orthop Clin N Am. 2009;40:311-20.

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3. Lovell TP. Single-incision direct anterior approach for total hip arthroplasty using

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a standard operating table. J Arthroplasty. 2008;23(7) Suppl 1:64-8. 4. Bender B, Nogler M, Hozack WJ. Direct anterior approach for total hip

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arthroplasty. Orthop Clin N Am. 2009;40:321-28. 5. Meneghini RM, Pagnano MW, Trousdale RT, Hozack WJ. Muscle damage during

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MIS total hip arthroplasty: Smith Peterson versus posterior approach. Clin

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Orthop Rel Res. 2006;0:1-6.

6. Bergin PF, Doppelt JD, Kephart CJ, Benke MT, Graeter JH, et al. Comparison of

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minimally invasive direct anterior versus posterior total hip arthroplasty based on

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inflammation and muscle damage markers. J Bone Joint Surg Am. 2011;1392-98. 7. Lugade V, Wu A, Jewett B, Collis D, Chou L. Gait asymmetry following an anterior and anterolateral approach to total hip arthroplasty. Clin Biomechanics. 2010;25:625-80. 8. Vail TP, Mariani EM, Boune MH, Berger RA, Meneghini RM. Approaches in total hip arthroplasty. J Bone Joint Surg Am. 2009;91:10-12. 9. Bal BS, Lowe JA, Gietler AE, Aleto TJ. Heterotopic ossification after 2-incision total hip arthroplasty. J Arthroplasty. 2010;25(4):538-40.

ACCEPTED MANUSCRIPT 10. Goel A, Sharp DJ. Heterotopic bone formation after hip replacement: The influence of the type of arthritis. J Bone Joint Surg Br. 1991;73-B(2):255-257.

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11. Higo T, Mawatari M, Shigematsu M, Hotokebuchi T. The incidence of

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heterotopic ossification after cementless total hip arthroplasty. J Arthroplasty. 2006;21(6):852-56.

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12. Pai VS. Heterotopic ossification in total hip arthroplasty: the influence of

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approach. J Arthroplasty. 1994;9:199-202.

13. Sneath RJ, Bindi FD, Davies J, Parnell EJ. The effect of pulsed irrigation on the

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incidence of heterotopic ossificiation after total hip arthroplasty. J Arhtroplasty. 2001;16(5):547-551.

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14. Spinarelli A, Patella V, Petnera M, Abate A, Pesce V, Patella S. Heterotopic

2011;95:1-5.

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ossification after total hip arthroplasty: our experience. Musculoskeletal Surg.

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15. Toom A, Haviko T, Rips L. Heterotopic ossification after total hip arthroplasty.

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Int Orthop. 2001;24:323-26. 16. Vastel L, Kerboul L, Anract P, Kerboul M. Heterotopic Ossification after total hip arthroplasty: Risk factors and prevention. Rev Rheum [Engl. Ed]. 1998;65(4):238-44. 17. Nilsson OS, Persson P. Heterotopic bone formation after joint replacement. Curr Opinion in Rheum. 1999;11:127-31. 18. Brooker AF, Bowerman JW, Robinson RA, Riley LH. Ectopic ossification following total hip replacement. J Bone Joint Surg Am. 1973;55-A:1629-32.

ACCEPTED MANUSCRIPT 19. Ritter MA, Vaughan RB. Ectopic ossification after total hip arthroplasty. J Bone Joint Surg. 1977;59-A(3):345-51.

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20. Kocic M, Lazovic M, Mitkovic M, Djokic B. Clinical significance of heterotopic

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ossification after total hip arthroplasty. Orthopedics. 2010;33(1):16. 21. Baird EO, Kang QK. Prophylaxis of heterotopic ossification – an updated review.

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Springer-Verlag, Berlin. 1983.

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22. Bombelli R. Osteoarthritis of the hip: Classification and pathogenesis. 2nd ed.

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23. Pellegrini VD, Gregoritch SJ. Preoperative irradiation for prevention of heterotopic ossification following total hip arthroplasty. J Bone Joint Surg.

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1996;78-A(6):870-81.

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24. Cohn RM, Della Valle AG, Cornell CN. Heterotopic ossification is less after total hip arthroplasty in patients who receive aspirin compared to Coumadin.

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Bulletin of the NYU Hospital for Joint Diseases. 2010;68(4):266-72.

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25. Beck B, Beksac B, Della Valle AG, Sculco TP, Salvati EA. Aspirin decreases the prevalence and severity of heterotopic ossification after 1-stage bilateral total hip arthroplasty for osteoarthrosis. J Arthroplasty. 2009;24(2):226-32.

ACCEPTED MANUSCRIPT Figure Legend Table 1. Incidence of heterotopic ossification.

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Figure 1. Preoperative radiograph demonstrating atrophic arthritis.

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Figure 2. 6 month follow-up radiograph demonstrating Brooker class III heterotopic ossification.

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27. Fig. 1

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29. Fig. 2

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Relative Risk

95% CI

X2 (df)

p-value

36/106 (33.0) 62/127 (48.8)

1.48

1.07, 2.04

6.02

0.14

Male Female

60/123 (48.8) 38/113 (33.6)

0.62

0.50, 0.95

5.57

0.02

Yes No

58/122 (47.5) 40/114 (35.1)

1.35

0.99, 1.85

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3.76

0.52

Yes No

19/74 (25.7) 79/162 (48.8)

0.53

0.35, 0.88

11.15

0.001

Yes No

22/46 (47.8) 76/190 (40.0)

1.20

0.84, 1.69

0.93

0.33

Type of arthritis Hypertrophic Atrophic Neutral

31/77 (40.3) 32/72 (44.4) 16/47 (34.0)

n/a

n/a

1.28 (2)

0.53

Age group < 45 years 45-65 years > 65 years

4/14 (28.6) 48/125 (38.4) 46/97 (47.4)

n/a

n/a

2.85 (1)*

0.09

Body Mass Index Underweight Normal Overweight Obese I Obese II Obese III

0/1 (0) 26/69 (37.7) 42/103 (40.8) 24/51 (47.1) 4/9 (44.4) 2/3 (66.7)

n/a

n/a

1.82 (1)*

0.18

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Hospital Hospital 1 Hospital 2 Gender

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Coumadin

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Lovenox

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Incidence of HO (%)

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Table 1. Incidence of HO

* denotes linear regression df – degrees of freedom