We thank Dr. Brannon for his interest in our paper and for his questions. We agree that more extensive debridement in the free vascularized fibula graft (FVFG) may have contributed to the more favorable results when compared to the non vascularized fibula graft (NVFG) group. Also, we agree that the size of the core tract needed for FVFG is based on its being large enough to avoid compression of the peroneal vessels; a concern not at issue with NVFG.

The dense necrotic bone of the osteonecrotic lesion is first removed using a low speed reamer and further bone is removed circumferentially through a narrow core tract with a curette to make mushroom defect.

The surgical transarticular approach described by Mont (1), and the approach via the femoral neck described by Rosenwasser (2) must be performed with an arthrotomy, which is not necessary using our technique.

A true comparison of FVFG to NVFG would require performing identical procedures in both groups, and only anastomosis in the FVFG group on small to medium lesions, a group where Urbaniak (3) reports his best results. We also agree with this comment.

The natural history and the results of other surgical procedures including VFG (3-4) have shown that small to medium lesions located medially or centrally in hips with less than 2 mm collapse, are much less likely to progress to collapse than lesions that occupy most of the weight-bearing area (5-7). Recently, attention has been directed at the treatment of large, laterally-located osteonecrotic lesions without collapse.

We did not intend to de-emphasize the work of Mont and Rosenwasser which demonstrated that femoral head sphericity can be maintained with debridement alone, even in the absence of providing blood flow with a FVFG. This is also possible through impaction grafting through a core tract. Rijnen, et al, (8) reported a 70% radiographic success rate of bone impaction grafting through a core tract for extensive (combined necrotic angle more than 200 degrees) ONFH in younger patients (mean age 33years, range 15 to 55 years) with a minimum 2 years follow- up. However, patients with preoperative collapse had disappointing results.

Our study evaluated the effectiveness of FVFG and NVFG for large sized lesions and showed FVFG had better clinical and radiographic results of Steinberg IIc lesions at a minimum 3 years follow-up. We think that using FVFG for large lesions changes the size and location of the lesion through the regeneration of bone tissue (biological aspect) and providing a living bone strut (mechanical aspect) even though it cannot cure the large necrotic lesions (9).

References:

1. Rosenwasser MP, Garino JP, Kiernan HA, Michelsen CB. Long term followup of thorough debridement and cancellous bone grafting of the femoral head for a vascular necrosis. Clin Orthop. 1994; 306: 17-27.

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

3. Urbaniak JR, Harvey EJ. Revascularization of the Femoral Head in Ostenonecrosis. J Am Acad Orthop Surg. 1998; 6:44-54.

4. Sugioka Y, Hotokebuchi T, Tsutsui H. Transtrochanteric anterior osteotomy for idiopathic and steroid-induced necrosis of the femoral head. Indications and long-term results. Clin Orthop. 1992; 277:111-120.

5. Nishii T, Sugano N, Ohzono K, Sakai T, Haraguchi K and Yoshikawa H: Progression and cessation of collapse in osteonecrosis of the femoral head. Clin Orthop, 400: 149-57, 2002.

6. Ohzono K, Saito M, Takaoka K, Ono K, Saito S, Nishina T, Kadowaki T. Natural history of nontraumatic avascular necrosis of the fempral head. J Bone Joint Surg.1991;73-B:68-72.

7. Sugano N, Atumi T, Ohzono K, Kubo T, Hotokebuchi T. The 2001 revised criteria for diagnosis, classification, and staging of idiopathic osteonecrosis of the femoral head. J Orthop Sci. 2002;7:601-605.

8. Rijnen WH, Gardeniers JW, Buma P, Yamano K, Slooff TJ and Schreurs BW. Treatment of femoral head osteonecrosis using bone impaction grafting. Clin Orthop. 2003; 417: 74-83.

9. Brown TD, Pederson DR, Baker KJ, Brand KJ. Mechanical consequences of core tract and bone grafting on osteonecrosis of the femoral head. 1993;75 -A:1358-1367.

To the Editor:

After reading the article, "Vascularized Compared with Nonvascularized Fibular Grafts for Large Osteonecrotic Lesions of the Femoral Head" by Kim, et al, and the letter to the editor by Dr. Wells I would like to offer some comments.

Kim et al. described better clinical results for large lesions with free vascularized fibula grafting (FVFG) when compared to non vascularized fibula grafting (NVFG). Dr. Wells commented that the improved clinical results were possibly due to more debridement of necrotic bone and cited the references of Mont (1) and Rosenwasser(2). Kim et al. responded that the core tract with the NVFG was indeed smaller (but sufficient) when compared to that used with FVFG. I believe Kim et al. comment this way because the size of the core tract needed for FVFG is based on its being large enough to avoid compression of the peroneal vessels; a concern not at issue with NVFG.

Importantly, the result of core tract preparation for FVFG is “thorough” debridement, and this should not be discounted. While Kim et al attribute the success of FVFG to the graft, their more thorough debidement in this group may have contributed to a better result when compared to the NFVG group with a smaller tract and therefore less complete debridement. Further, the dense necrotic bone characteristic of osteonecrosis cannot be removed through a narrow core tract with a curette, and I am certain the authors encountered this.

The real issue is whether the MRI according to the Steinberg classification truly quantifies the necrotic burden within the femoral head. It is more likely that large core tracts would remove more necrotic bone and allow more autologous cancellous bone to be packed into the femoral head.

Kim et al. further comment that Mont(2) and Rosenwasser(1) used avascular bone graft for “smaller” lesion. It is possible that Mont and Rosenwasser suggested this limitation because their approach, transarticular-Mont, and via the femoral neck-Rosenwasser, has the potential to put the femoral head at risk for collapse and the femoral neck at risk for fracture, and not the limitation implied by Kim et al.,that “avascular bone grafting will fail if used for larger lesions”.

The work of Mont and Rosenwasser is also important because these investigators demonstrated that femoral head sphericity can be maintained in the absence of providing blood flow with a FVFG. It is interesting to note that Kim et al. have taken a position that de-emphasizes the importance of thorough debridement in the ABSENCE of a vascularized fibula particularly in view of the real question being “does the VASCUALRIZED fibula provide femoral head longevity?” While FVFG is compared to NVFG, the surgical techniques are NOT comparable. A true comparison of FVFG to NVFG is to perform identical procedures in both, and only the anastomosis in the FVFG group on small to medium lesions; a group where Urbaniak reports his best results. (6) Performing FVFG on large lesions is an effort to expand the indications for the procedure and not for proof of concept.

I applaud Kim et al. for their interesting work, but one wonders if more of the femoral heads in the NVFG could have been preserved had they been thoroughly debrided as in the FVFG.

References:

1. Rosenwasser MP, Garino JP, Kiernan HA, Michelsen CB. Long term followup of thorough debridement and cancellous bone grafting of the femoral head for a vascular necrosis. Clin Orthop, 1994; 306: 17-27.

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

3. Day SM, Ostrum RF, Chao EYS, Clinton RT, Aro HT, Einhorn TA: Bone injury, regeneration, and repair. In: JA Buckwalter, TA Einhorn, SR Simon editors. Orthopaedic basic sciences: Biology and biomechanics of the musculoskeletal system, 2nd edition. Rosemont, American Academy of Orthopaedic Surgeons, 2000; p. 388.

4. Enneking, W.F., et al., Retrieved Human Allografts, JBJS American 83: 971-986 2001.

5. Plakseychuk AY, Kim S-Y, Park B-C, Varitimidis SE, Rubash HE, Sotereanos DG: Vascularized compared with nonvascularized fibula grafting for the treatment of osteonecrosis of the femoral head. J Bone Joint Surg Am, 2003;85:589-596.

6. Urbaniak, James et al., Revascularization of the Femoral Head in Ostenonecrosis Journal of the American Academy of Orthopaedic Surgeons, 1998;6:44-54.

We thank Dr. Wells for his interest in our paper and for his questions. We agree that more extensive debridement in the free vascularized fibula graft (FVFG) may have contributed to the more favorable results when compared to the non vascularized fibula graft (NVFG) group. In the FVFG hips, we tried to remove as much necrotic bone as possible and create a mushroom-shaped defect. Local autologous cancellous bone was packed into the defect through the 10-24mm diameter core tract and the size of the mushroom-shaped bone defect and the amount of packed cancellous bone graft were definitely larger in the FVFG group.

More importantly, however, the FVFG group had better results because FVFG is associated with a more rapid induction of primary callus formation in the subchondral bone as a result of more robust revascularization and increased osteoinductive potential of the vascularized graft. Also, we think making the same sized core tract in NVFG is unnecessary.

Dr. Wells cited two studies (1,2) that reported favorable results using nonvasularized bone grafting based upon the principles of a through debridement of the necrotic area followed by bone grafting of the defect. We cannot compare our results with the results of those papers directly. Rosenwasser, et al, (1) did not evaluate their data according to the size of the necrotic lesion; and Mont, et al, (2) did not use the Steinberg classification but, rather, used the combined Kerboul angle. Also, Mont, et al, recommended this procedure only to treat small and medium-sized lesion. Our study evaluated the effectiveness of FVFG and NVFG for large sized lesions.

References:

1. Rosenwasser MP, Garino JP, Kiernan HA, Michelsen CB. Long term followup of thorough debridement and cancellous bone grafting of the femoral head for a vascular necrosis. Clin Orthop, 1994; 306: 17-27.

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

To The Editor:

I would like to thank Kim et al for a very interesting comparison of the use of vascularized and nonvascularized grafts for the treatment of osteonecrotic lesions of the femoral head.

I am writing to suggest that differences in surgical techniques may have influence the results. My reading of the materials and methods section indicates that the amount of femoral head debridement in both stage 2 groups was different. The FVFG had a core tract of 18-24 mm augmented further by creating a mushroom excavation of the femoral head while the non vascularized group reportedly had a core tract of 12-15 mm. It is quite possible that the more extensive debridement in the FVFG led to the favorable results reported.

Rosenwasser, et al(1) and Mont, et al(2) have reported favorable results using nonvascularized bone grafting based upon the principles of a thorough debridement of the necrotic area followed by bone grafting of the defect.

References:

1. Rosenwasser MP, Garino JP, Kiernan HA, Michelsen CB, Long term Followup fo thorough debridement and cancellous bone grafting of the femoral head for a vascular necrosis. Clinical Orthopaedics & Related Research, 1994; No. 306: 17-27.

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