- Email: [email protected]
Protrusio Acetabuli: Some Questions
Letters to the Editor Protrusio Acetabuli: Some Questions
To the Editor: I read with interest the case report by Dr. Dean Matsuda describing arthroscopic treatment for the management of protrusio acetabuli.1 I commend the author on his ability to access very difficult anatomic regions with an arthroscopic approach. Protrusio acetabuli is a very complex pathomorphology, and the ideal surgical treatment for the patient with continued disability is controversial on many fronts. Technically, a global rim resection is demanding arthroscopically but definitely feasible with experience, as shown in the case report. The bigger question, however, may regard the most appropriate treatment rather than the approach. Recent evidence out of Switzerland from Ferguson et al.2 suggests that a number of cases of protrusio present with a large lunate fossa and normal or decreased overall acetabular articular cartilage surface area. A finite element model showed that the primary site of increased stress was at the medial aspect of the hip joint rather than at the rim. Finite element analysis after global rim resection in this situation showed even greater stresses medial within the joint. A global rim resection in this setting, therefore, might not be the most ideal treatment whether performed in an open manner or arthroscopically; Leunig et al.3 have proposed that an anteversion periacetabular osteotomy with posterior rim resection and, in some cases, proximal femoral osteotomy might be considered. I would also ask Dr. Matsuda to comment on the ability to dynamically assess this difficult case arthroscopi-
cally with severe global overcoverage of the acetabulum and decreased head-neck offset that extends posteriorly as well. Protrusio is certainly an unsolved treatment dilemma. We should stress that further studies and outcomes are necessary to better determine the most appropriate treatment for this and other hip pathomorphologies before the entire hip arthroscopy community adds this to its list of indications. Again, I commend the author on his efforts and abilities to take on such a case. Christopher Larson, M.D. Edina, Minnesota The author reports that he has no conflicts of interest in the authorship and publication of this letter.
References 1. Matsuda DK. Protrusio acetabuli: Contraindication or indication for hip arthroscopy? And the case for arthroscopic treatment of global pincer impingement. Arthroscopy 2012;28:882-888. 2. Ferguson SJ, Liechti EF, Tannast M. Joint degeneration pattern in severe pincer impingement and its implications for surgical therapy. In: 2012 ORS annual meeting program. Rosemont, IL: Orthopaedic Research Society, 2012. 3. Leunig M, Nho SJ, Turchetto L, Ganz R. Protrusio acetabuli: New insights and experience with joint preservation. Clin Orthop Relat Res 2009;467:2241-2250.
© 2012 by the Arthroscopy Association of North America
http://dx.doi.org/10.1016/j.arthro.2012.06.007
Author’s Reply I sincerely appreciate the valued queries and comments from Dr. Larson. I think we would agree with Dr. James Heckman, past Editor-in-Chief of The Journal of Bone and Joint Surgery, that “No one study—no matter how good it is or how profound it seems—should change the course of clinical care. You must have the data corroborated and have the experiment repeated by someone else.”1 This would apply even more so to any case report. The intent of my report was to show the feasibility of less invasive arthroscopic surgery in the treatment of extreme global acetabular overcoverage, not to suggest that the rendered surgery is the only or best procedure for all patients with acetabular protrusion. In addition, by showing feasibility in this
instance, one may envision that less severe deformities may be treatable with arthroscopic means. I tried to emphasize in the Discussion, though admittedly not exhaustively, that there may be differing pathomechanisms and procedures for a broad spectrum of these patients. The reference to an often large acetabular fossa is appreciated as we learn more about “medial dysplasia.” There was no intent to generalize; rather, my intent was to form a rationale for the individualized surgery for this specific patient. With regard to the comments on posterosuperior cam decompression and arthroscopic dynamic examinations in this setting, I agree that these are challenging procedures and hope to have future submissions on these specific
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 28, No 9 (September), 2012: pp 1193-1196
1193
To the Editor: I read with interest the case report by Dr. Dean Matsuda describing arthroscopic treatment for the management of protrusio acetabuli.1 I commend the author on his ability to access very difficult anatomic regions with an arthroscopic approach. Protrusio acetabuli is a very complex pathomorphology, and the ideal surgical treatment for the patient with continued disability is controversial on many fronts. Technically, a global rim resection is demanding arthroscopically but definitely feasible with experience, as shown in the case report. The bigger question, however, may regard the most appropriate treatment rather than the approach. Recent evidence out of Switzerland from Ferguson et al.2 suggests that a number of cases of protrusio present with a large lunate fossa and normal or decreased overall acetabular articular cartilage surface area. A finite element model showed that the primary site of increased stress was at the medial aspect of the hip joint rather than at the rim. Finite element analysis after global rim resection in this situation showed even greater stresses medial within the joint. A global rim resection in this setting, therefore, might not be the most ideal treatment whether performed in an open manner or arthroscopically; Leunig et al.3 have proposed that an anteversion periacetabular osteotomy with posterior rim resection and, in some cases, proximal femoral osteotomy might be considered. I would also ask Dr. Matsuda to comment on the ability to dynamically assess this difficult case arthroscopi-
cally with severe global overcoverage of the acetabulum and decreased head-neck offset that extends posteriorly as well. Protrusio is certainly an unsolved treatment dilemma. We should stress that further studies and outcomes are necessary to better determine the most appropriate treatment for this and other hip pathomorphologies before the entire hip arthroscopy community adds this to its list of indications. Again, I commend the author on his efforts and abilities to take on such a case. Christopher Larson, M.D. Edina, Minnesota The author reports that he has no conflicts of interest in the authorship and publication of this letter.
References 1. Matsuda DK. Protrusio acetabuli: Contraindication or indication for hip arthroscopy? And the case for arthroscopic treatment of global pincer impingement. Arthroscopy 2012;28:882-888. 2. Ferguson SJ, Liechti EF, Tannast M. Joint degeneration pattern in severe pincer impingement and its implications for surgical therapy. In: 2012 ORS annual meeting program. Rosemont, IL: Orthopaedic Research Society, 2012. 3. Leunig M, Nho SJ, Turchetto L, Ganz R. Protrusio acetabuli: New insights and experience with joint preservation. Clin Orthop Relat Res 2009;467:2241-2250.
© 2012 by the Arthroscopy Association of North America
http://dx.doi.org/10.1016/j.arthro.2012.06.007
Author’s Reply I sincerely appreciate the valued queries and comments from Dr. Larson. I think we would agree with Dr. James Heckman, past Editor-in-Chief of The Journal of Bone and Joint Surgery, that “No one study—no matter how good it is or how profound it seems—should change the course of clinical care. You must have the data corroborated and have the experiment repeated by someone else.”1 This would apply even more so to any case report. The intent of my report was to show the feasibility of less invasive arthroscopic surgery in the treatment of extreme global acetabular overcoverage, not to suggest that the rendered surgery is the only or best procedure for all patients with acetabular protrusion. In addition, by showing feasibility in this
instance, one may envision that less severe deformities may be treatable with arthroscopic means. I tried to emphasize in the Discussion, though admittedly not exhaustively, that there may be differing pathomechanisms and procedures for a broad spectrum of these patients. The reference to an often large acetabular fossa is appreciated as we learn more about “medial dysplasia.” There was no intent to generalize; rather, my intent was to form a rationale for the individualized surgery for this specific patient. With regard to the comments on posterosuperior cam decompression and arthroscopic dynamic examinations in this setting, I agree that these are challenging procedures and hope to have future submissions on these specific
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 28, No 9 (September), 2012: pp 1193-1196
1193