JBJS welcomes reader comments on published articles. Letters to the Editor are reviewed by JBJS editors but are not peer-reviewed. To submit your letter, please follow the "submit a response" link that appears in the content box at the upper right of the full text of the article.

Letters to the Editor to:

Scientific Articles:
Ching-Jen Wang, Jun-Wen Wang, Lin-Hsiu Weng, Chia-Chen Hsu, Chung-Cheng Huang, and Han-Shiang Chen
The Effect of Alendronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part of the Tibia After Total Knee Arthroplasty
J Bone Joint Surg Am 2003; 85: 2121-2126 [Abstract] [Full text] [PDF]
*Letters to the Editor: Submit a response to this article

Electronic letters published:

[Read Letter to the Editor] Dr Wang responds to Dr Alexandropoulos
Chin-Jen Wang, M.D., Jun-Wen Wang, Lin-Hsiu Weng, Chia-Chen Hsu, Chung-Cheng Huang, and Han-Shiang Chen.   (26 April 2004)
[Read Letter to the Editor] The Effect of Alendronate on Bone Mineral Density
Christos Alexandropoulos   (26 April 2004)
[Read Letter to the Editor] Dr. Wang responds:
Ching-Jen Wang, M.D., Jun-Wen Wang, M.D., Lin-Hsiu Weng, M.D., Chia-Chen Hsu, M.D., Chung-Cheng Huang, M.D.   (21 April 2004)
[Read Letter to the Editor] Dr Wang responds:
Ching-Jen Wang, Jun-Wein Wang, L H Wend, CC Hsu, CC Huang and HS Chen   (10 February 2004)
[Read Letter to the Editor] The Effect of Alendronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part
Tarja A Soininvaara, Kuopio University Hospital   (10 February 2004)

Dr Wang responds to Dr Alexandropoulos 26 April 2004
Previous Letter to the Editor Top
Chin-Jen Wang, M.D.,
Orthopedic Surgeon
Chang Gung Memorial Hospital, Dept., Orthopedic Surgery, Kaohsiung, Taiwan 833,
Jun-Wen Wang, Lin-Hsiu Weng, Chia-Chen Hsu, Chung-Cheng Huang, and Han-Shiang Chen.

Send letter to journal:
Re: Dr Wang responds to Dr Alexandropoulos

w281211{at}adm.cgmh.org.tw Chin-Jen Wang, M.D., et al.

We like to respond to the questions raised by Christos Alexandropoulos in reference to our recent article entitled "The effect of alendronate on bone mineral density ... after total knee arthroplasty" (2003;85:2121-6 Am). We did measure the BMD on the contralateral knee in this study. The BMD of the distal femur showed an increase of 11.6% +/- 22.2% in the alendronate group versus a decrease5.2% +/- 16.6% in the control group at 6 months. The BMD of the proximal tibia showed an increase of 6.3% +/- 26.5% in the alendronate group versus a decrease of 2.3% +/- 10/1% in the control group at 6 months. The data at one year postoperative were much lower.

We also analysed the BMD data on the contralateral knees into two groups; one group with prior TKA and the other had no surgery. The BMD changes with or without prior TKA were very similar. Therefore, the BMD changes on the contralteral knees were similar to those noted on the operated knees in our study. We did not include the data on the contralateral knees because they were irrevelant to the goal of our study. We hope that we have adequately answered the questions and addressed the concerns.
The Effect of Alendronate on Bone Mineral Density 26 April 2004
Previous Letter to the Editor Next Letter to the Editor Top
Christos Alexandropoulos
Trikala General Hospital

Send letter to journal:
Re: The Effect of Alendronate on Bone Mineral Density

alexand8{at}otenet.gr Christos Alexandropoulos

To the Editor:

Regarding the article “ The Effect of Aledronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part of the Tibia After Total Knee Replacement” (2003;85:2121-6) by CJ Wang et al, I would like to make some observations.

In this study aledronate was administered in non osteoporotic patients and the increased Bone Mineral Content (BMC) of the operated tibia and femur that measured, considered that possibly improves the prosthetic fixation of the Total Knee Arthroplasty. This would be good news.

But, surprisingly in this paper there are no data about the BMC increase of the non operated knee. Since aledronate has a systematic effect, one can expect an increased BMC in both knees and eventually on both hips. It is not clear how this iatrogenic alteration of BMC affects healthy major joints. For example, one can suppose that BMC increase may lead to subchondral sclerosis and rapid osteoarthritic degeneration of these joints.

MM Petersen et al(1), investigating the effect of nasal salmon calcitonin on post-traumatic osteopenia following ankle fracture measured the BMC in both operated and healthy tibiae and and found a statistically significant increase on BMC in the healthy leg tibia.

I believe that not only the improvement of the prosthetic components fixation but the effects of aledronate on the non osteoporotic patients’ major joints must be investigated in order the clinical importance of this study be evaluated. If the authors have obtained relative data the clinical follow up will be of great value.

Yours sincerely

Christos Alexandropoulos, MD Orthopaedic Department of Trikala General Hospital

Reference: 1. Petersen MM, Lauritzen JM, Schwarz P, Lund B. Effect of nasal salmon calcitonin on post traumatic osteopenia following ankle fracture. A randomized double-blind placebo-controlled study in 24 patients. Acta Orthop Scand. 1998 Aug; 69(4): 347-50

Corresponding address: Christos Alexandropoulos, MD 20, Triantafilou str., 42100 Trikala, Greece e-mail: alexand8@otenet.gr
Dr. Wang responds: 21 April 2004
Previous Letter to the Editor Next Letter to the Editor Top
Ching-Jen Wang, M.D.,
Orthopedic Surgeon
Chang Gung Memorial Hospital, Department of Orthopedic Surgery, Kaohsiung, Taiwan 833,
Jun-Wen Wang, M.D., Lin-Hsiu Weng, M.D., Chia-Chen Hsu, M.D., Chung-Cheng Huang, M.D.

Send letter to journal:
Re: Dr. Wang responds:

w281211{at}adm.cgmh.org.tw Ching-Jen Wang, M.D., et al.

To the Editor:

We like to respond to the questions raised by Dr.Alexandropoulos in reference to our recent article entitled "The effect of alendronate on bone mineral density ... after total knee arthroplasty" (2003;85:2121-6 Am). We did measure the BMD on the contralateral knee in this study. The BMD of the distal femur showed an increase of 11.6% +/- 22.2% in the alendronate group versus a decrease5.2% +/- 16.6% in the control group at 6 months. The BMD of the proximal tibia showed an increase of 6.3% +/- 26.5% in the alendronate group versus a decrease of 2.3% +/- 10/1% in the control group at 6 months. The data at one year postoperative were much lower.

We also analysed the BMD data on the contralateral knees into two groups; one group with prior TKA and the other had no surgery. The BMD changes with or without prior TKA were very similar. Therefore, the BMD changes on the contralteral knees were similar to those noted on the operated knees in our study. We did not include the data on the contralateral knees because they were irrevelant to the goal of our study. We hope that we have adequately answered his questions and concerns.
Dr Wang responds: 10 February 2004
Previous Letter to the Editor Next Letter to the Editor Top
Ching-Jen Wang,
Physician
Chang Gung Memorial Hospital,
Jun-Wein Wang, L H Wend, CC Hsu, CC Huang and HS Chen

Send letter to journal:
Re: Dr Wang responds:

w281211{at}adm.cgmh.org.tw Ching-Jen Wang, et al.

Dear Editor, This is to acknowledge the receipt of the letter to Editor from Tarja A. Soininvaara regarding our article. We would like to congratulate them on their study showing favorable effect of alendronate on periprosthetic bone, findings that are similar to our study. In their study, patients treated with alendronate plus calcium maintained distal femur BMD values close to the baseline, while patients who received only calcium showed significant bone loss during the one-year post TKA.

The groups differed significantly in BMD in the metaphyseal and diaphyseal regions of interest. In their study, patients were allowed full weight bearing immediately after the operation, and the BMD was performed within one week, and at 3, 6, and 12 months postoperatively. In our study, the BMD was performed within one week preoperatively and at 6 and 12 months postoperatively. The geometries of the distal femur and the proximal tibia for BMD measurements were determined preoperatively. The same geometries were used for subsequent BMD measurements postoperatively. Thus, similar measurement areas can be secured and the values of measurement are reproducible.

We have noted a wide range of BMD values among the patients. Therefore, we analyzed the results based on the mean ˇÓ SD values. In our study, patients were allowed to bear partial weight on the operated leg for 4 to 6 weeks before full weight bearing. In fact, the majority of patients were unable to bear full weight for approximately 4 weeks due to postoperative pain even though they were allowed to do so. Weight bearing may theoretically affect the BMD; however, short-term partial weight bearing (4 to 6 weeks) does not seem to cause any detrimental effect on BMD around the knee.

The BMD measurement of the proximal part of the tibia was divided into three regions of interest (ROI): the lateral region (ROI-1), the medial region (ROI-2), and the center region (ROI-3). The medial and lateral regions were located at 1.0 cm within the cortex and 1.0 cm distal to the prosthesis-bone interface, and the center region was located at 1.0 cm distal to the prosthetic stem. We only used one type of prosthesis in this study, and the prosthesis-bone interface in the medial and lateral regions can be fair precisely estimated preoperatively. Likewise, the tip of the prosthesis stem can be determined accordingly. Such measurements can minimize or eliminate the effect of cement mantle on BMD values.

The BMD values in the ROIs in Table IV are the average values of BMD measurement in anteroposterior and lateral projections. These regions were so chosen because they theoretically sustain the most stress shielding and the changes in BMD, if any, will most likely occur in these locations.

Overall, we agree with the writer's opinions that there is a favorable effect of alendronate on periprosthetic bone after TKA. We like to thank the writer for his valuable opinions and comments.

Ching-Jen Wang, M.D.
The Effect of Alendronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part 10 February 2004
Next Letter to the Editor Top
Tarja A Soininvaara,
M.D.,
Savonlinna Central Hospital,
Kuopio University Hospital

Send letter to journal:
Re: The Effect of Alendronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part

tarja.soininvaara{at}uku.fi Tarja A Soininvaara, et al.

To The Editor:

We read with great interest "The Effect of Alendronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part of the Tibia After Total Knee Arthroplasty" by Wang et al. (2003; 85-A:2121- 2126)(1).

We have previously shown the efficacy of oral alendronate with calcium for the inhibition of early BMD loss after TKA in a prospective, randomized, one-year follow-up study. Periprosthetic BMD changes were measured in 19 patients with knee osteoarthrosis with dual-energy X-ray absorptiometry within a week post-operatively and at 3, 6 and 12 months follow-up. Patients treated with alendronate+calcium maintained distal femoral BMD values close to the baseline (from 0.48% to –5.5, P > 0.04), while patients receiving only calcium showed significant bone loss during the one-year (from –14.3% to –23.6%, P < 0.015). The groups differed significantly in metaphyseal and diaphyseal regions of interests (ROI)(2). These ROIs are reproducible, with an average precision error ranging from 1.3% to 3.1% (3). Full weight-bearing was allowed immediately after the operation(2-4).

The present study by Wang, et al., raises some questions. The authors used the preoperative BMD measurement as a baseline reference in their patients. We would like to know the reproducibility of their measurements. How did they verify that they measured the areas in the pre- and postoperative scans? What is the effect of the cement mantle and perioperative bone loss on these measurements? What was the duration and the effect of partial weight-bearing on BMD?

The ranges of BMDs and their percent changes are very wide. Although the BMD increase at 6 months is marked (10 %) in the study group, the 12 months change may not be significant (1.9 %).

According to both studies, alendronate treatment seems to prevent bone loss after TKA. The long-term effect of bisphosphonates in prevention of aseptic loosening needs to be investigated.

Tarja A Soininvaara, M.D. and Heikki Kröger, M.D., Ph.D

Department of Surgery, Savonlinna Central Hospital, Savonlinna, Finland. Department of Surgery, Kuopio University Hospital, Kuopio, Finland. Bone and Cartilage Research Unit (BCRU), University of Kuopio, Kuopio, Finland. Tarja.Soininvaara@uku.fi

References

1. Ching-Jen Wang, Jun-Wen Wang, Lin-Hsiu Weng, Chia-Chen Hsu, Chung- Cheng Huang, Chen. H-S 2003 The Effect of Alendronate on Bone Mineral Density in the Distal Part of the Femur and Proximal Part of the Tibia After Total Knee Arthroplasty. J Bone Joint Surg Am 85:2121-2126. 2. Soininvaara TA, Jurvelin JS, Miettinen HJ, Suomalainen OT, Alhava EM, Kroger HPJ. 2002 Effect of alendronate on periprosthetic bone loss after total knee arthroplasty: a one-year, randomized, controlled trial of 19 patients. Calcif Tissue Int. Dec;71(6):472-7. 3. Soininvaara T, Kroger H, Jurvelin JS, Miettinen H, Suomalainen O, Alhava E 2000 Measurement of bone density around total knee arthroplasty using fan-beam dual energy X-ray absorptiometry. Calcif Tissue Int Sep 67(3):267-72. 4. Soininvaara TA, Miettinen HJA, Jurvelin JS, Suomalainen OT, Alhava EM, Kroger HPJ. Periprosthetic femoral bone loss after total knee arthroplasty: one-year follow-up study of 69 patients. The Knee (In press).