We would like to thank Dr. Maheshwari et al. for their interest in our study. They have raised an interesting point regarding the risk of patella baja after different types of approaches in total knee arthroplasty. We had an independent, blinded, experienced radiographer measure the Insall-Salvati ratio on all the patients in our study. The preoperative average ratio of all seventy-eight knees was 1.037. There were a total of five knees in three patients with ratios <0.8. The preoperative average ratios of the subluxation and eversion groups were 1.036 and 1.038, respectively. The average postoperative ratios of the subluxation and eversion groups were 1.061 and 1.059, respectively. All five knees with preoperative ratios <0.8 had a similar finding postoperatively, and the average change in ratio was 0.02. We agree that the development of patella baja can be problematic after total knee arthroplasty. Because of the numbers in our study, we were unable to show, regardless of surgical approach, any increased risk of development of patella baja or its exacerbation it if it existed preoperatively.

To the Editor:

We read with great interest the article by Dalury et al., "Early Recovery After Total Knee Arthroplasty Performed with and without Patellar Eversion and Tibial Translation. A Prospective Randomized Study" (1). First of all, we would like to congratulate the authors for a well designed study which attempts to answer a perpetual controversy: the role of patellar eversion and the "Ransall maneuvre" on the functional outcome (in other words, the indirect controversy between the minimal invasive (MIS) and the traditional long incision surgery).

We would like to ask the authors if they found any increased incidence of patella baja in any of the groups. If yes, was the technique related to the development of patella baja? The resultant patella baja in some "traditional aproach" studies has been linked to poor functional outcomes (2-4). On the other hand, some studies have found no influence of patella baja on function (5,6). Although this study may be statistically underpowered to answer this question and there was no functional difference, the trend in this study would be interesting to discuss.

In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants of less than $10,000 from Wright/Link and Exactech. In addition, one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits of less than $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Wright/Link, Exactech, Depuy, and Smith and Nephew). 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. Dalury DF, Mulliken BD, Adams MJ, Lewis C, Sauder RR, Bushey JA. Early recovery after total knee arthroplasty performed with and without patellar eversion and tibial translation. A prospective randomized study. J Bone Joint Surg Am. 2009;91:1339-43.

2. Flören M, Davis J, Peterson MG, Laskin RS. A mini-midvastus capsular approach with patellar displacement decreases the prevalence of patella baja. J Arthroplasty. 2007;22(6 Suppl 2):51–7.

3. Weale AE, Murray DW, Newman JH, Ackroyd CE. The length of the patellar tendon after unicompartmental and total knee replacement. J Bone Joint Surg Br. 1999;81:790–5.

4. Meneghini RM, Ritter MA, Pierson JL, Meding JB, Berend ME, Faris PM. The effect of the Insall-Salvati ratio on outcome after total knee arthroplasty. J Arthroplasty. 2006;21(6 Suppl 2):116–20.

5. Koshino T, Ejima M, Okamoto R, Morii T. Gradual low riding of the patella during postoperative course after total knee arthroplasty in osteoarthritis and rheumatoid arthritis. J Arthroplasty. 1990;5:323–7.

6. Gatha NM, Clarke HD, Fuchs R, Scuderi GR, Insall JN. Factors affecting postoperative range of motion after total knee arthroplasty. J Knee Surg. 2004;17:196–202.