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Femoral Head Bone-Preserving Procedures   |    
Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head
Christian J.H. Veillette, MD, FRCS(C), MSc, BSc(Hon); Hossein Mehdian, MD; Emil H. Schemitsch, MD, FRCS(C); Michael D. McKee, MD, FRCS(C)
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The authors did not receive grants or outside funding in support of their research for or preparation of this manuscript. One or more of the authors received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (Zimmer, Inc.). No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

The Journal of Bone and Joint Surgery, Incorporated
J Bone Joint Surg Am, 2006 Nov 01;88(suppl 3):48-55. doi: 10.2106/JBJS.F.00538
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Abstract

Background: For early stages of osteonecrosis, preservation of the femoral head is the primary objective; however, there has not been a consensus on how best to achieve this goal. Core decompression alone is associated with a lack of structural support with inconsistent outcomes, whereas vascularized fibular grafting requires an extensive surgical procedure with high donor-site morbidity and prolonged rehabilitation. The adjunctive use of a porous tantalum implant offers the advantages of core decompression, structural support, minimally invasive surgery, and no donor-site morbidity. The purpose of this study was to assess the survivorship and to evaluate the clinical results and radiographic outcomes of hips in which osteonecrosis of the femoral head was treated with core decompression and a porous tantalum implant.

Methods: We evaluated fifty-four patients (sixty consecutive hips) in whom osteonecrosis of the femoral head was treated with core decompression and insertion of a porous tantalum implant. Fifty-two patients (fifty-eight hips) were available for follow-up at a mean of twenty-four months. All patients were sixty-five years of age or younger (mean age, thirty-five years). According to the classification system of Steinberg et al., one hip (2%) had stage-I disease, forty-nine hips (84%) had stage-II disease, and eight hips (14%) had stage-III disease. Outcome measures that were used included a limb-specific score (Harris hip score), radiographic outcome measures, and survivorship analysis with revision to total hip arthroplasty as the end point.

Results: Overall, nine hips (15.5%) were converted to total hip arthroplasty, including six with stage-II disease and three with stage-III disease. The overall survival rates were 91.8% (95% confidence interval, 87.8% to 95.8%) at twelve months, 81.7% (95% confidence interval, 75.8% to 87.6%) at twenty-four months, and 68.1% (95% confidence interval, 54.7% to 81.5%) at forty-eight months. The absence of chronic systemic diseases resulted in a survival rate of 92% at forty-eight months (95% confidence interval, 87.4% to 96.4%).

Conclusions: Treatment of early stage osteonecrosis of the femoral head with core decompression and a porous tantalum implant can be accomplished with a minimally invasive technique and no donor-site morbidity. The early clinical results show encouraging survival rates in patients who do not have chronic systemic disease, especially in association with early stage disease.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

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    Michael D. McKee, MD, FRCSC
    Posted on February 12, 2009
    Dr. McKee responds to Dr. Pandher and colleagues
    St. Michael's Hospital, Toronto, ON

    I am pleased to have the opportunity to respond to the letter by Dr. Pandher regarding our article entitled “Survivorship analysis and radiographic outcome following tantalum rod insertion for osteonecrosis of the femoral head” (1). I agree with Dr. Pandher that the short term clinical results of this implant have been very encouraging for patients with pre-collapse AVN of the femoral head. I also agree that longer term follow up will be important. We have not noticed any substantial deterioration of results since the paper was published and it is our preliminary impression that if the femoral head survives the first 2 to 3 years post AVN rod insertion, then the rate of long term success is good. This would suggest that success is not attributable to the core decompression effect alone.

    This procedure is not universally successful and we have experience with the reconstruction of some of the failures of this technique at our institution. Our intra-operative findings have been that bone growth into the tantalum rod, especially in the femoral head and neck distal to the osteonecrotic focus, has been extremely robust. In fact, removal of the rod can be quite technically challenging in the majority of reconstructive settings. In addition, we have noted a variable degree of bone ingrowth into the rod in the actual area of the osteonecrotic lesion and also have seen some patients where bone ingrowth has been “discouraging” as noted by Tanzer et al (2). Certainly this is an area that needs further study.

    We agree with Dr. Pandher that the extent of osteonecrosis of the femoral head, and not only the state of collapse, is important in terms of prognosis and outcome. We agree that a variety of sizes, especially larger implants would be useful in patients who have greater involvement of the femoral head, or who are physically larger. We are promoting the development of a range of implanted rods for this exact purpose.

    The two patients who underwent conversion to total hip arthroplasty without radiographic evidence of progression are certainly interesting. The indication for conversion total hip arthroplasty in both patients was unrelenting pain. At surgery, we were unable to find any clear mechanical reason for their pain and there was no evidence of any other contributing factors such as infection. One patient had almost complete relief of pain following conversion arthroplasty and the other was substantially improved but still had a moderate level of pain. Clearly, some other factor or factors are influencing outcomes but they remain to be elucidated. It is possible that some form of localized regional pain syndrome may be the cause of the intense discomfort these individuals felt. It is also possible that some as yet poorly understood physical or mechanical lesion in the femoral head itself was responsible.

    References

    1. Veillette CJ, Mehdian H, Schemitsch EH, McKee MD. Survivorship analysis and radiographic outcome following tantalum rod insertion for osteonecrosis of the femoral head. J Bone Joint Surg Am. 2006; 88:48-55.

    2. Tanzer M, Bobyn JD, Krygier JJ, Karabasz D. Hisopathologic retrieval analysis of clinically failed porous tantalum osteonecrosis implants. J Bone Joint Surg Am. 2008; 90: 1282-9.

    Dilbans S. Pandher, MS(Orth)
    Posted on January 03, 2009
    Clinical Failure of Tantalum Rod without Radiological Progression
    Oxford Superspecialty Hospital

    To the Editor:

    We read with interest, the article, “Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head” by Veillette et al [1]. To date, the short term clinical results of the implant have been reported to be encouraging in patients with early osteonecrosis of the femoral head (1,2,3), but it will be more revealing to learn how results using this implant will be in the longer term, after the effects attributable to core decompression alone have been factored out. A review of 1206 hips treated by core decompression alone reported 63.5% satisfactory clinical results at a mean follow-up of 30 months [4].

    The rationale for the use of the tantalum implant is that the high porosity of the material, its fully interconnected pores, the osteoconductive microtexture of the tantalum struts, and an elastic modulus that is similar to that of the cancellous bone will provide mechanical support and possibly allow bone growth into the avascular femur head [5-7]. However a retrieval study, has reported discouraging results as far as new bone formation or vascular invasion into the osteonecrotic portion of the femur head (8). In contrast, some evidence of bony growth into the implant, and new bone formation or vascular invasion of the necrotic bone was reported in MRI and bone scintigraphy studies[9,10].

    We have two concerns regarding this study(1). The first concern is that authors did not mention the extent of osteonecrosis in terms of percentage of the joint surface involved in all the cases. This information would be of help because a retrieval study (8) suggested that availability of larger sizes of implants might be indicated for implantation in osteonecrotic femoral head with greater degrees of head involvement.

    Secondly, the authors reported that two hips without radiographic progression nevertheless required conversion to total hip arthroplasty. We too have experienced a case of tantalum rod failure without any evidence of radiological progression of the disease. In our patient, the histopathological examination of the retrieved implant showed new bone formation around the porous tantalum. We would be interested to learn from the authors of the current article what they believe to be the cause of these failures.

    The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

    References

    1. Veillette CJ, Mehdian H, Schemitsch EH, McKee MD. Survivorship analysis and radiographic outcome following tantalum rod insertion for osteonecrosis of the femoral head. J Bone Joint Surg Am. 2006; 88:48-55.

    2. Shuler MS, Rooks MD, Roberson JR. Porous tantalum implant in early osteonecrosis of the hip: preliminary report on operative, survival, and outcomes results. J Arthroplasty. 2007; 22:26-31.

    3. Aldegheri R, Taglialavoro G, Berizzi A. The tantalum screw for treating femoral head necrosis: rationale and results. Strategies Trauma Limb Reconstr. 2007; 2:63-8.

    4. Mont MA, Carbone JJ, Fairbank AC. Core decompression versus non- operative management for the osteonecrosis of the hip joint. Clin Orthop Relat Research. 1996; 324:169-78.

    5. Zimmer. Surgical techniques brochure: Trabecular Metal Osteonecrosis Intervention Implant. 2005.

    6. Bobyn JD, Poggie RA, Krygier JJ, Lewallen DG, Hanssen AD, Lewis RJ, Unger AS, O’Keefe TJ, Christie MJ, Nasser S, Wood JE, Stulberg SD, Tanzer M. Clinical validation of a structural porous tantalum biomaterial for adult reconstruction. J Bone Joint Surg Am. 2004; 86:123-9.

    7. Tsao AK, Roberson JR, Christie MJ, Dore DD, Heck DA, Robertson DD, Poggie RA. Biomechanical and clinical evaluations of a porous tantalum implant for the treatment of early-stage osteonecrosis. J Bone Joint Surg Am. 2005; 87:22-7.

    8. Tanzer M, Bobyn JD, Krygier JJ, Karabasz D. Histopathologic retrieval analysis of clinically failed porous tantalum osteonecrosis implants. J Bone Joint Surg Am. 2008; 90:1282-9.

    9. Mitchell DG, Rao VM, Dalinka MK, Spritzer CE, Alavi A, Steinberg ME, Fallon M, Kressel HY. Femoral head avascular necrosis: correlation of MR imaging, radiographic staging, radionuclide imaging, and clinical findings. Radiology. 1987; 162:709-15.

    10. Beltran J, Herman LJ, Burk JM, Zuelzer WA, Clark RN, Lucas JG, Weiss LD, Yang A. Femoral head avascular necrosis: MR imaging with clinical- pathologic and radionuclide correlation. Radiology. 1988; 166:215-20.

    James K. Brannon, M.D.
    Posted on January 22, 2007
    The Treatment of ONFH Must Include Relief of Pain
    UMKC School of Medicine, Dept. Orthopaedic Surgery, Truman Medical Centers, Kansas City, MO

    To The Editor:

    I would like to thank Dr. McKee et al. for responding to my Letter to the Editor. Indeed, I read with great interest their comments concerning the article "Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head,” by Veillette et al.(1) Notwithstanding the response of Dr. McKee et al., I additionally have considerable experience in treating osteonecrosis and believe that further dialogue regarding the issues raised would be helpful.

    Dr. Mckee et al. responded that the mean Harris Hip Score, HHS, was 72 for the stage III hips in their study so as to imply that the stage III hips, on a weighted average, lowered the POST-OPERATIVE HHS of the 54 available hips for review to a mean of 80. This may be the case. However, the issue raised was not the statistical burden 28 fair and bad hips had on the 26 good to excellent hips, but rather WHY the procedure described was considered a success when only one patient was shown to have a clinical improvement in their HHS. Over the 2 year study period, 26 hips were scored as good to excellent pre-operatively and 27 were scored as good to excellent post-operatively. I agree that a HHS between 80 and 85 is better for a 35 year old patient (mean age of the study population) than a total hip arthroplasty; however, I would not consider this a good outcome when the HHS for 26 of the hips in the Veillette et al.(1) study remained unchanged throughout the study period. Dr. Mckee et al. comment, in view of the natural history of ONFH, that such an observation is “compelling” evidence that the procedure described has a substantial effect on halting the progression of disease. More importantly, was the insertion of the tantalum rod effective in relieving pain, a parameter assessed with the HHS? Interestingly, Marciniak et al. in their review of 101 hips treated with FVFG comment on the importance of patient selection, and further emphasize recognition of the socioeconomic impact osteonecrosis had on their patient population, wherein nearly 53% of the hips treated in their study developed disease secondary to steroids.(2) How are Dr. Mckee et al. able to conclude that the data presented is “compelling” when the patients treated continued with their presenting symptoms for an additional 2 years (Veillette et al.’s mean follow-up period)? In view of Marciniak et al.,(2) one can reasonably conclude that a continuously painful hip will have an increasing negative impact on the patient, thus making a total hip arthroplasty, when it is ultimately performed, less likely to allow the affected patient to return to reasonable socioeconomic function. If one is to consider a 35 year old patient with a HHS of 80 to be a “good” hip, then why was the hip operated IF success is considered continued pain and NO improvement in the hip score rating? I recognize that the duration of symptoms was not an objective of the Veillette et al.(1) study; however, this consideration should not be discounted. Dr. McKee et al. seem to imply that a good clinical outcome is characterized by a femoral head that remains spherical “longer,” yet painful. In view of the data presented by Veillette et al.(1) the insertion of the tantalum rod did not improve outcomes with respect to pain (the parameter most relevant to the patient) and I would like to further emphasize the goal of joint preservation surgery, i.e., preservation of the joint AND relief of pain. A prospective randomized trial would have been a better statistical format to support the comments made by Dr. McKee et al.

    Regarding core decompression, outcomes have varied from as low as 17 percent (seven of forty-one in the series reported by Learmonth et al.(3)) to as high as 89 percent (119 of 133, as reported by Ficat(4)). Importantly, these outcomes may vary because lesion size varies within a given early stage. I believe Steinberg et al.(5) recognized this and developed a staging system that includes MRI findings. Dr. Mckee et al. responded that the MRI results were NOT available for the patients in their study, yet the Steinberg system was used. Recently, Steinberg and Steinberg(6) demonstrated how to use digital radiography to determine lesion size when the MRI is NOT available. Therefore, how do Veillette et al. and the response of Dr. Mckee laud the insertion of the tantalum rod when the size of the lesion and the mechanical consequences of drilling into lesions of “variable sizes” are NOT known? If the HHS score was NOT to improve in 26 of the hips in the current study, could one have simply performed a CD on these hips and expected clinical results within the range of those reported?

    Indeed, one can argue about the bone physiology within a lesion at the time of tantalum rod insertion; however, the basic science of new bone formation(7) offers sound advice about what is required. Necrotic bone within the femoral head should be debrided, the residual site grafted, and the residual cavity stabilized when necessary. Aside from the basic science at hand, if necrotic bone were found at a nonunion fracture site, it would be removed, yet when necrotic bone is found within the femoral head, its removal is debated. In my view, removal of the necrotic bone is debated because sufficient means for stabilization after thorough debridement are not available in a minimally invasive way. How does one stabilize the subchondral bone within a femoral head having a large cavity resulting from thorough debridement? Urbaniak achieves stabilization with the fibula.(8) Indeed, the treatment for osteonecrosis remains controversial and such controversy may continue because “thorough debridement” is NOT recognized as a major contributing factor influencing outcome. Urbaniak(8) has demonstrated clinical success with FVFG as Dr. Mckee et al. may have at their institution, but the role of thorough debridement described in the surgical technique of FVFG is NOT emphasized enough. Rosenwasser et al.(9) recognized the importance of thorough debridement and included this term in the title of their paper describing the lightbulb procedure. Hernigou et al.(10) suggested that mesenchymal cells were deficient within the femoral head of patients with osteonecrosis wherein Gangji et al.(11) tested this hypothesis and reported a good clinical outcome (relief of symptoms) in 10 of 18 hips treated with the implantation of bone marrow mononuclear cells at 24 months. Thus, I continue to suggest that the implantation of bone marrow is likely required in view of thorough debridement, an at risk residual host bed after thorough debridement, and the basic science of new bone formation. Could the HHS have improved in more than one patient in the Veillette et al.(1) study had more of the necrotic bone been removed? One wonders if the 35 year old patient with a Steinberg stage I or stage II hip and a HHS of 80 could have experienced 2 years of pain relief had he/she undergone a procedure consisting of thorough debridement. If Dr. McKee et al. argue that a total hip arthroplasty is difficult after a failed FVFG, then I would think better patient selection, as suggested by Marciniak(2), could possibly limit the number of failures experienced by them.

    In summary, the treatment for osteonecrosis remains controversial. I believe this to be the case because of a lack of consensus of opinion regarding the common features the successful procedures, vascular and nonvascular, have in common. Further, most published studies list conversion to a total hip as the end point for failure. Clearly, this emphasizes the suggestion that patients have their hips replaced because of pain and loss of function. The deteriorating socioeconomic status for these young patients with continued pain must be recognized. Our center has had extensive experience in treating osteonecrosis of all major diarthrodial joints in patients aged 8 to 71 years. We employ the basic science of new bone formation, i.e., thorough debridement, bone grafting, and stabilization when necessary using in a minimally invasive technique. Dr. Mckee et al. comment that there are numerous surgical techniques for treating ONFH, and I agree. Perhaps these can be reduced in number if the common features of the known successful procedures are elucidated and applied more consistently.

    The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors, or a member of his or her immediate family, received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Orthopedic Sciences, Inc.) No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

    References:

    1. Veillette CJH, Mehdian H, Schemitsch EH, and McKee MD. Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head. J Bone Joint Surg Am. 2006; 88(Supp 3):48-55.

    2. Marciniak D, Furey C, and Shaffer JW. Osteonecrosis of the Femoral Head. A Study of 101 Hips Treated with Vascularized Fibular Grafting. J. Bone Joint Surg. Am., Apr 2005; 87: 742 - 747.

    3. Learmonth ID, Maloon S, and Dali G. Core decompression for early atraumatic osteonecrosis of the femoral head. J. Bone and Joint Surg., 72- B(3): 387-390, 1990

    4. Ficat, R. P. Idiopathic bone necrosis of the femoral head. Early diagnosis and treatment. J. Bone and Joint Surg., 67-B(1): 3-9, 1985.

    5. Steinberg ME, Hayken GD, Steinberg DR: A Quantitative system for staging avascular necrosis. J Bone and Joint Surg Br, 1995;77:34-41.

    6. Steinberg DR, Steinberg ME, GarinoJP, Dalinka M, and Udupa JK. Determining Lesion Size in Osteonecrosis of the Femoral Head. J Bone Joint Surg Am. 2006; 88(Supp 3):27-34.

    7. Day SM, Ostrum RF, Chao EYS, et al: Bone injury, regeneration, and repair. In JA Buckwalter JA, TA Einhorn TA, SR Simon SR (eds). Orthopaedic basic sciences: Biology and biomechanics of the musculoskeletal system, 2nd edition. Rosemont, American Academy of Orthopaedic Surgeons 388 2000.

    8. Urbaniak JR, Coogan PG, Gunneson EB, Nunley JA. Treatment of osteonecrosis of the femoral head with free vascularized fibular grafting. A long-term follow-up study of one hundred and three hips. J Bone Joint Surg. Am.1995;77: 681-694.

    9. Rosenwasser MP, Garino JP, Kierman HA, Michelsen CB: Long-term follow-up of thorough debridement and cancellous bone grafting of the femoral head for avascular necrosis. Clin Orthop, 1994;306:17-27.

    10. Hernigou, P, and Beaujean, F. Abnormalities in the Bone Marrow of the Iliac Crest in Patients Who Have Osteonecrosis Secondary to Corticosteroid Therapy or Alcohol Abuse. J. Bone Joint Surg. Am., Ju11997; 79: 1047-53.

    11. Gangji V, Hauzeur J-P, Matos C, De Maertelaer V, Toungouz M, and Lambermont M. Treatment of Osteonecrosis of the Femoral Head with Implantation of Autologous Bone-Marrow Cells. A Pilot Study. J. Bone Joint Surg. Am., Jun 2004; 86: 1153

    Michael McKee, M.D., FRCS(C)
    Posted on January 10, 2007
    Dr. McKee, et al. respond to Dr. Brannon
    Dept. Orthopaedic Surgery, University of Toronto, St. Michael's Hospital, Toronto, ON, CANADA

    We thank you for the opportunity to respond to the letter by Dr. Brannon regarding our recent article “Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head”(1).

    1. Dr. Brannon states that the pre-operative average Harris hip score in our patients was 81 points. This is true for the hips with stage I or stage II disease. The hips with stage III disease had lower pre-operative scores (mean 72). Thus, on average, hips treated with this technique were as good or better post operatively than they were pre-operatively. Given the poor natural history of ONFH, one could reasonably expect that over the follow up period there would be a substantial deterioration of hip scores for this population. That this did not occur is, we feel, compelling evidence that the procedure we described has a substantial effect in halting the progression of the disease. We would agree with Dr. Branson that this does not necessarily make involved hips “normal”, but we do believe that a spherical femoral head with a Harris hip score between 80 and 85 is probably better for a 35 year old patient (mean age of the patients in our series) than a total hip arthroplasty.

    2. While we agree that the volume of the lesion does probably relate to prognosis, we believe that the most important prognostic variable is the stage of collapse of the articular surface, which is defined by the Steinberg classification system which we used. For this reason we have elected to report our results based on the Steinberg stage of the lesion rather than the volumetric assessment of lesion size. While we agree that a volumetric assessment would be reasonable, our understanding is the most accurate way to do this is with MRI evaluation pre-operatively and up to date MRI information of this nature was not available for all patients.

    3. We agree with Dr. Brannon that this procedure is not universally successful, as evidenced by Dr. Tanzer’s retrieval of analysis of 18 failed cases (2). We agree that Dr. Tanzer’s study documented that in treated hips that failed, porous metal placed against necrotic bone was not associated with new bone formation. However, it may be that in successful cases, femoral head architecture is maintained long enough for natural bone healing with revascularization from the periphery of the lesion to occur. Thus, while one can argue about the bone physiology that occurs in the lesion at the time of rod insertion, the clinical evidence suggests that, especially for patients without chronic systemic disease, this procedure seems to be successful in arresting the progression of femoral head change.

    4. We don’t believe that it is universally agreed that the successful treatment of osteonecrosis absolutely requires the delivery of additional viable mesenchymal cells. Theoretically, especially with a peripheral lesion, such cells already exist in the femoral head and if the femoral head architecture can be maintained while a healing or reparative process occurs from these adjacent cells, then clinical success is still possible. Certainly there are many series in the literature which describe techniques such core decompression alone with some success where no mesenchymal cells are delivered to the avascular focus(3). It may be that the stimulatory effect of the reaming, the mechanical support of the tantalum rod, and the natural repair process may be sufficient to maintain femoral head sphericity, decrease pain, and result in clinical success. The presence of active systemic chronic disease would theoretically decrease the ability of local and adjacent mesenchymal cells to participate in the healing or reparative process. The poor results seen in our series in such individuals would support this theory.

    5. We have had extensive experience with the use of free vascularized fibular grafting for ONFH, having performed over 300 such procedures (4). Unfortunately, they fail as well, as evidenced by our own series (5). In our experience, if failure does occur, the surgical morbidity, time involvement, rehabilitation, and difficulty of conversion to total hip arthroplasty is substantially decreased with the tantalum rod technique as opposed to the vascularized fibular graft technique.

    In summary, we would agree with Dr. Brannon that core decompression and tantalum rod insertion for osteonecrosis of the femoral head is not universally successful and the pathophysiology of the reparative process in the femoral head and the effect the tantalum rod has on it remains to be elucidated. Our institution has an extensive experience with multiple surgical techniques for treating ONFH. (including over 300 cases of free vascularized fibular grafting), We have found, with the exception of treating patients with chronic diseases, that this technique can halt the progression of osteonecrosis in a high percentage of individuals. We continue to use this technique in our institution as we follow our patients for longer follow up periods.

    References:

    1. Veillette CJH, Mehdian H, Schemitsch EH and McKee MD: Survivorship analysis and radiographic outcome following tantalum rod insertion for osteonecrosis of the femoral head, J Bone and Joint Surgery (A) 2006; 88(Supp 3): 48-55.

    2. Tanzer M: Retrieval analysis of a porous tantalum intervention implant in early stage osteonecrosis http://www3.aaos.orgl education! anmeet! Anmt2006/poster/poster. Cfm ?Pevent= PO 5 9.

    3. Brown TD, Pedersen DR, Baker KJ, and Brand RA: Mechanical consequences of core drilling and bone-grafting on osteonecrosis of the femoral head, J Bone Joint Surg(A), Sep 1993; 75: 1358-1367.

    4. Louie BE, McKee MD, Richards RR, Mahoney JL, Waddell JP, Beaton DE, Schemitsch EH, Yoo D: Treatment of osteonecrosis of the femoral head by free vascularized fibular grafting, Canadian Journal of Surgery, 1999; Vol. 42-No.4: 274-283.

    5. Davis ET, McKee MD, Waddell JP, Hupel T: Total hip arthroplasty following failure of free vascularized fibular graft, J Bone Joint Surgery(A), 2006; 88A: 110-116.

    James K. Brannon, M.D.
    Posted on November 24, 2006
    The Treatment of Early Stage Osteonecrosis
    University of Missouri, Dept. of Orthopaedic Surgery, Kansas City, MO. 64139

    To The Editor:

    In their article, "Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head," Veillette et al.(1) conclude that successful treatment of early stage disease (Steinberg stages I and II) can be accomplished with use of a trabecular metal implant (Osteonecrosis Intervention Implant, Zimmer, Warsaw, IN) into the core tract of a femoral head. The perceived benefits of the implant are that it provides mechanical support to the subchondral plate and stabilization of the femoral head and neck after core decompression. Although stabilization of the core tract is important, it is the presence of new living bone in the subchondral region that promotes femoral head longevity. Veillette et al.(1) survivorship analysis raises several concerns that I would like to address.

    Veillette et al.(1) treated sixty hips, of which 54 were available for review at a mean follow-up of 24 months. 2% were Steinberg stage I, 84% were Steinberg stage II, and 14% were Steinberg stage III. The survival rates at 12 months, 24 months, and 48 months, were 91.8%, 81.7%, and 68.1%, respectively. The average POSTOPERATIVE Harris hip score for the 54 available hips was 80 points (range 55 to 96). 27 hips were scored as good to excellent: 18 good, and 9 excellent. However, the PREOPERATIVE average Harris hip score was 81 points (range 55 to 96) with 26 hips being scored as good to excellent; 17 good and 9 excellent. Thus, 9 excellent hips remained excellent, 17 good hips remained good, 1 hip that was either fair or poor improved to good, and nine hips were converted to THA.. One wonders why Veillette et al.(1) concluded that the procedure was successful. Did the patients with good to excellent hips in the study experience relief of pain, or does this study simply characterize longevity of a femoral head as one that may have remained painful, yet was too spherical for replacement?

    With respect to staging of the disease, Steinberg and Steinberg(2) recently demonstrated that a volumetric assessment of lesion size within the femoral head may be more accurate than angular measurements. Steinberg and Steinberg(2) further commented that it has been well established that outcome in the management of the precollapse hip is affected by the size of the lesion. Importantly, variability of outcomes following core decompression may be explained by variability of lesion size within a given early stage. Veillette et al.(1) did not clarify the size of the lesions in their study. How does insertion of a tantalum rod into lesions that are of variable sizes and were not debrided affect outcomes?

    At the 2006 annual AAOS meeting, Tanzer(3) reported a retrieval analysis of 18 femoral heads that had been treated with insertion of a tantalum rod for early stage (I and II) osteonecrosis. The mean age of Tanzer's patients was 46 years (range 31-61). Tanzer found at a mean of 13.4 months (range 3-36) all femoral heads demonstrated collapse and the bone surrounding the implant remained necrotic without evidence of revascularization or healing. Tanzer et al.(3) documented that porous metal placed against necrotic bone was not likely to induce new bone formation. The question arises whether incorporation of the tantalum rod occurs in the subchondral region, or is incorporation limited to the intertrochanteric region of the proximal femur?

    A review of the literature suggests that successful treatment of osteonecrosis requires the delivery of viable mesenchymal cells to the necrotic bone as suggested by Hernigou et al.(4) and applied by Gangji et al.(5) I do not believe that the addition of autologous bone marrow with the insertion of the tantalum rod addresses the problem sufficiently. There is a remaining necrotic burden within the femoral head after core decompression, although Veillette at al.(1) imply that there is no adverse clinical consequence of less than thorough debridement of the femoral head. Do Veillette et al.(1) espouse less than thorough debridement because the removal of more necrotic bone would destabilize the femoral head and render the tantalum rod an ineffective tool for stabilization of the subchondral bone as recognized by Brown et al?(6)

    Urbaniak(7), Mont(8), and Rosenwasser(9) have shown that femoral head longevity (sphericity) accompanied by relief of pain can be achieved when the femoral head is thoroughly debrided and a rich source of viable mesenchymal cells are delivered to the remaining host bed. Urbaniak believes these cells require a blood supply, i.e., the FVFG, whereas Mont and Rosenwasser rely on the remaining host bed to provide a blood supply. Veillette et al.(1) performed neither thorough debridement nor suggested/demonstrated how the tantalum rod would be incorporated into living bone while in contact with the subchondral plate of the femoral head.

    I commend Veillette et al.(1) for presenting this new technique. I believe that the gold standard for treatment of early stage ONFH has been established by the results of Urbaniak, Mont, and Rosenwasser whose techniques include thorough debridement of the necrotic lesion and introduction of a viable source of new bone. Newer techniques that offer a less invasive approach and eliminate donor site morbidity must produce comparable results.

    The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors, or a member of his or her immediate family, received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Othopedic Sciences, Inc.) No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

    References:

    1. Veillette CJH, Mehdian H, Schemitsch EH, and McKee MD. Survivorship Analysis and Radiographic Outcome Following Tantalum Rod Insertion for Osteonecrosis of the Femoral Head. J Bone Joint Surg Am. 2006; 88(Supp 3):48-55.

    2. Steinberg DR, Steinberg ME, GarinoJP, Dalinka M, and Udupa JK. Determining Lesion Size in Osteonecrosis of the Femoral Head. J Bone Joint Surg Am. 2006; 88(Supp 3):27-34.

    3. Tanzer M. Retrieval Analysis Of A Porous Tantalum Intervention Implant In Early Stage Osteonecrosis http://www3 .aaos. orgl education! anmeetl anmt2006/poster/poster. cfm ?Pevent= PO 5 9

    4. Hernigou, P, and Beaujean, F. Abnormalities in the Bone Marrow of the Iliac Crest in Patients Who Have Osteonecrosis Secondary to Corticosteroid Therapy or Alcohol Abuse. J. Bone Joint Surg. Am., Ju11997; 79: 1047 - 53.

    5. Gangji V, Hauzeur J-P, Matos C, De Maertelaer V, Toungouz M, and Lambermont M. Treatment of Osteonecrosis of the Femoral Head with Implantation of Autologous Bone-Marrow Cells. A Pilot Study. J. Bone Joint Surg. Am., Jun 2004; 86: 1153 - 1160.

    6. Brown TD, Pedersen DR, Baker KJ, and Brand RA. Mechanical consequences of. core drilling and bone-grafting on osteonecrosis of the femoral head. J. Bone Joint Surg. Am., Sep 1993; 75: 1358 - 1367.

    7. Urbaniak JR, Coogan PG, Gunneson EB, and Nunley JA: Treatment of osteonecrosis of the femoral head with free vascularized fibular. A long- term follow-up study of one hundred and three hips. J Bone Joint Surg Am, 1995; 77:681-94.

    8. Mont MA, Einhorn TA, Sponseller PD, and Hungerford DS: The trapdoor procedure using autogenous cortical and cancellous bone grafts for osteonecrosis of the femoral head. J Bone and Joint Surg Br, 1998; 80:56- 62.

    9. Rosenwasser MP, Garino JP, Kierman HA, Michelsen CB: Long-term follow-up of thorough debridement and cancellous bone grafting of the femoral head for avascular necrosis. Clin Orthop, 1994; 306:17-27.

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