Letters to the Editor / The Journal of Arthroplasty 29 (2014) 448–451
of agreement between DrGoniometer and a universal goniometer was 10.26° (− 5.75°/+4.51°) in the first paper [4], and 14.1° (− 7.5°/ + 6.6°) in the second one [5]. Taken together, these results demonstrate that both kinds of application (accelerometer- and photographic-based) are reliable in the angle measurements analyzed. The accelerometer-based applications may offer the advantage of self-measurement by the patient, while the photographic-based applications enable one to save or print the images, which can be included in the patient's medical record as evidence of the care provided. Moreover the photographicbased measurement can be used in the operating room without the need for any particular provision, as it does not require any contact with the skin. Further studies are warranted to comparatively assess the strengths and weaknesses of these two kinds of smartphone applications, accelerometer- and photographic-based, in joint angle measurement, particularly in patients with problematic goniometer placement, as in obesity or limb deformities. Giorgio Ferriero, MD Stefano Vercelli, MSc Francesco Sartorio, PT Unit of Occupational Rehabilitation & Ergonomics Scientific Institute of Veruno, Fondazione Salvatore Maugeri IRCCS, Veruno (NO), Italy Calogero Foti, MD Chair of Physical and Rehabilitation Medicine University of Rome “Tor Vergata”, Rome, Italy
http://dx.doi.org.10.1016/j.arth.2013.06.014
References 1. Jenny JY. Measurement of the knee flexion angle with a smartphone-application is precise and accurate. J Arthroplasty, http://dx.doi.org/10.1016/j.arth.2012.11.013. [Epub ahead of print]. 2. Hambly K, Sibley R, Ockendon M. Level of agreement between a novel smartphone application and a long arm goniometer for the assessment of maximum active knee flexion by an inexperienced tester. Int J Physiother Rehabil 2012;2:1. 3. Ockendon M, Gilbert RE. Validation of a novel smartphone accelerometer-based knee goniometer. J Knee Surg 2012;25(4):341. 4. Ferriero G, Sartorio F, Foti C, et al. Reliability of a new application for smartphones (DrGoniometer) for elbow angle measurement. PM R 2011;3(12):1153. 5. Ferriero G, Vercelli S, Sartorio F, et al. Reliability of a smartphone-based goniometer for knee joint goniometry. Int J Rehabil Res 2013;36(2):146.
Answer to Ferriero et al About “Measurement of the Knee Flexion Angle…”
Dear Editor, I read the letter by Ferriero et al [1] with great interest and I appreciated their valuable comments. I fully agree with their statement that both accelerometer- and photographic-based applications are reliable tools for the knee angle measurement. Indeed, further studies are warranted to comparatively assess the strengths and weaknesses of these two kinds of applications. Our study compared actually the smartphone measurement to a validated, non biased reference measurement technique. We demonstrated that the smartphone application had an acceptable accuracy for the majority of patients. However, the study quoted about the knee joint [2] was a comparison between two different measurement devices. The reference tool for this study was a universal goniometer, which is
449
known to involve possible bias [2–4]. The authors actually demonstrated that there was a good agreement between both measurement techniques, but did not compare these devices to a (supposed…) non biased reference technique. Consequently, they did not demonstrate that the photographic-based application was not biased. After having read their paper, we eventually planned to perform a new study comparing both accelerometer- and photographic-based applications to the navigation reference. Sincerely yours, Jean-Yves Jenny, MD
http://dx.doi.org.10.1016/j.arth.2013.06.013
References 1. Letter Ferriero et al. [E-pub ahead of print]. 2. Ferriero G, Vercelli S, Sartorio F, et al. Reliability of a smartphone based goniometer for knee joint goniometry. Int J Rehabil Res 2012;36(2):146. 3. Lavernia C, D'Apuzzo M, Rossi MD, et al. Accuracy of knee range of motion assessment after total knee arthroplasty. J Arthroplasty 2008;23(6 Suppl 1):85. 4. Lenssen AF, Van Dam EM, Crijns YH, et al. Reproducibility of goniometric measurement of the knee in the in-hospital phase following total knee arthroplasty. BMC Musculoskelet Disord 2007;8:83.
Letter to the Editor: In Response to “Modular Taper Junction Corrosion and Failure: How to Approach a Recalled Total Hip Arthroplasty Implant”
To the Editor: We read the article by Pivec et al on the approach to a recalled total hip arthroplasty with great interest. We applaud the authors for their thoughtful approach to this timely and increasingly difficult problem. While we agree with their overall assessment of the problem, based on our collective and extensive experience with the Rejuvenate stem, and to a lesser degree the ABG, we differ on the aggressiveness of their algorithm for both the diagnosis and treatment. Between our 4 centers, we have implanted 854 Rejuvenate stems and 91 ABGs. We have now reviewed serial metal serum ion levels and MRIs on nearly 85% of the patients. As the authors have, we would like to emphasize that while similar, these are two different stems. The Rejuvenate appears to be exhibiting a higher failure rate at the present time. This may however be simply time dependent, as the average time from index surgery is longer in the Rejuvenate group. The symptoms patients complain of are extremely subtle, most often complaining of groin pain, muscle fatigue, a fullness, achiness, and difficulty sleeping on that side. If one waits until the complaints are of significant pain and noticeable limp, abductor compromise has probably already occurred. One should also be attuned to systemic symptoms such as a rash or neurologic complaints, as these are frequently noted in our patients. We agree with the authors that while the Cobalt level is almost universally elevated, and the Chromium normal, they serve more as a baseline data rather than as absolutes for decision-making purposes. There is no known cutoff above which revision has been recommended. Patients however are very concerned with any elevated levels and time spent counseling them is required. The ESR is not surprisingly typically elevated, while the CRP is typically not. Both should be obtained and aspiration considered if both are elevated and one is worried about superimposed infection, or The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2013.10.028.
450
Letters to the Editor / The Journal of Arthroplasty 29 (2014) 448–451
a revision is pending. This aspiration can give you a definitive diagnosis of either infection, or Adverse Local Tissue Reaction (ALTR). Culture positive infections have been seen in 2–7% of our revisions. Because the patient’s symptoms are often times subtle, and asymptomatic patients have been found to have evidence of particle disease on MRI, we feel that ALL patients deserve a baseline MR imaging study. The study should be performed at a center with MARS capabilities, and by a radiologist with extensive experience with interpreting the images for this diagnosis. An ultrasound can be utilized if an MRI is not available or the patient has a pacemaker. Approximately 67% (range 53%–85%) of our MRIs demonstrated positive findings of particle disease, including effusions, pseudo tumors and tendonopathy. We have not seen an initial MRI study demonstrating positive signs of particle disease or ALTR return to normal. The MRI findings typically progress slowly over the next 3–6 month period. We do not yet have firm data on the rapidity with which it progresses but are looking carefully at that with serial MRIs. Additionally the problem has not been found to correlate with age, gender, time since implantation, weight, or patients' activity level. Because of the above, and until more is known about this unfolding problem, we feel the following should be included in any algorithm pertaining to the ongoing surveillance of these stems: • For asymptomatic patients with reasonable Cobalt levels (b 12 ug/L) and a normal MRI we recommend follow-up and repeating these studies at 6 months. • For asymptomatic patients with MRI findings of a large pericapsular fluid collection and/or a thickened encapsulating rind, a discussion dealing with probable revision should be undertaken with them. A follow-up at 3-4 months with repeat studies is recommended if they decline surgical intervention. • Symptomatic patients with positive findings on MRI, particularly with the presence of pseudo tumors or any soft tissue destruction, should be counseled and encouraged to proceed with prompt revision. • We do not have a cut off for cobalt ion levels above which, in the absence of true systemic symptoms, revision is recommended. The decision for revision is a difficult one, especially in patients with minimal symptoms. Our revision rates for the Rejuvenate between the 4 centers averages 51% (range 36–79%) and we anticipate this to continue to grow. The revision rate for the ABG is at 45%. In every case, significant corrosion at the neck stem junction has been seen in conjunction with variable degrees of ALTR. The revision of the stem is relatively straightforward in our hands with the expectation of good results if performed BEFORE soft tissue destruction occurs. Because of this, we counsel our patients with significant evidence of particle disease on MRI that it is a matter of when rather than if the implant revision will be required. While removal of an ingrown uncemented stem can be challenging, most can be removed with minimal metaphyseal bone loss (Paprosky 1 or 2) and typically without the need for an ETO. Fifteen percent of our patients required an ETO ranging from 1.8 to 45% at the 4 centers. The majority of the ETOs occurred earlier in our learning curve at one center prior to the development of our latest techniques. There were a few greater trochanteric fractures that healed following cabling, and we now prophalactically cable at risk trochanters. A video of the stem removal technique should be released soon. The timing of revision is based on the patient’s symptoms and MRI findings. In earlier disease with only small to moderate amounts of fluid and minimal marginal thickening, a reasonable delay for patient convenience is reasonable. For later stages, with the formation of pseudo tumors, and any compromise of the abductor tendons there is an urgency and revision should be performed in as judicious a manner as possible. Our worst results have been seen in those patients with significant destruction to their abductors. The repair of the hip
abductors is compromised by their poor vascularity secondary to the ALTR response to the corrosion at the head neck junction. This often requires a transfer of the Gluteus maximus and/or Tensor to regain abductor function. We believe all patients with one of these implants should be contacted and brought in for initial surveillance studies as outlined above. Additionally, physicians who are treating patients with this dual modular design need to be vigilant in evaluating their patient’s symptoms, exhaustive and persistent in their work-up, and prompt in their recommendation for revision if the patient has significant symptoms or findings on their MRIs suggestive of particle disease. Joseph F. Davies, William A. Leone, Joseph P. Nessler, Paul G. Perona,
MD MD MD MD
http://dx.doi.org.10.1016/j.arth.2013.10.028
Reply to Letter to the Editor by Davies et al
We thank the authors for their thorough letter concerning our report entitled “Modular Taper Junction Corrosion and Failure: How to Approach a Recalled Total Hip Arthroplasty Implant” (Pivec R, Meneghini RM, Hozack WJ, Westrich GH, Mont MA. J Arthroplasty. 2013 Sep 30. [Epub ahead of print]), which raises several pertinent questions regarding the treatment of these patients. As the authors noted, one of the most important considerations is when to recommend revision surgery for these patients and how to properly balance the risk of peri-operative complications with the risk of future muscle damage if surgery is delayed. This may be particularly challenging in the asymptomatic patient with normal metal ion levels. There was discussion among the co-authors on how to properly approach these patients and whether an MRI is warranted as a baseline test along with plain radiographs, serologic markers, and metal ion levels. Since the clinical experience has varied between the co-authors, it was believed that routine MRIs are something that the surgeon should consider based on their experience, but that there was not enough conclusive data to suggest an absolute recommendation, especially in asymptomatic patients. We did, however, have a consensus that evidence of elevated metal ions and/or symptoms was a clear indication for advanced imaging. The experience described by Davies and colleagues demonstrated that with a baseline MRI, adverse tissue reactions were seen in 67% of patients, which included both symptomatic and asymptomatic patients. It would be interesting to observe what the MRI-positive rate is for asymptomatic patients alone and this represents a future avenue of research. The authors also noted the progressive nature of tissue destruction with progression in all patients over a 3–6 month period, which emphasizes the importance of early intervention in the evidence of even mild muscle damage. This clinical experience led the authors to suggest modifications to our treatment algorithm to include a shorter follow-up period (6 months versus 1 year) in patients with no symptoms, nonelevated metal ions, and a normal MRI. Given the rapidity of tissue damage the authors observed in their cohort, we feel that a more aggressive follow-up period is a reasonable approach.
The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.10.029.
of agreement between DrGoniometer and a universal goniometer was 10.26° (− 5.75°/+4.51°) in the first paper [4], and 14.1° (− 7.5°/ + 6.6°) in the second one [5]. Taken together, these results demonstrate that both kinds of application (accelerometer- and photographic-based) are reliable in the angle measurements analyzed. The accelerometer-based applications may offer the advantage of self-measurement by the patient, while the photographic-based applications enable one to save or print the images, which can be included in the patient's medical record as evidence of the care provided. Moreover the photographicbased measurement can be used in the operating room without the need for any particular provision, as it does not require any contact with the skin. Further studies are warranted to comparatively assess the strengths and weaknesses of these two kinds of smartphone applications, accelerometer- and photographic-based, in joint angle measurement, particularly in patients with problematic goniometer placement, as in obesity or limb deformities. Giorgio Ferriero, MD Stefano Vercelli, MSc Francesco Sartorio, PT Unit of Occupational Rehabilitation & Ergonomics Scientific Institute of Veruno, Fondazione Salvatore Maugeri IRCCS, Veruno (NO), Italy Calogero Foti, MD Chair of Physical and Rehabilitation Medicine University of Rome “Tor Vergata”, Rome, Italy
http://dx.doi.org.10.1016/j.arth.2013.06.014
References 1. Jenny JY. Measurement of the knee flexion angle with a smartphone-application is precise and accurate. J Arthroplasty, http://dx.doi.org/10.1016/j.arth.2012.11.013. [Epub ahead of print]. 2. Hambly K, Sibley R, Ockendon M. Level of agreement between a novel smartphone application and a long arm goniometer for the assessment of maximum active knee flexion by an inexperienced tester. Int J Physiother Rehabil 2012;2:1. 3. Ockendon M, Gilbert RE. Validation of a novel smartphone accelerometer-based knee goniometer. J Knee Surg 2012;25(4):341. 4. Ferriero G, Sartorio F, Foti C, et al. Reliability of a new application for smartphones (DrGoniometer) for elbow angle measurement. PM R 2011;3(12):1153. 5. Ferriero G, Vercelli S, Sartorio F, et al. Reliability of a smartphone-based goniometer for knee joint goniometry. Int J Rehabil Res 2013;36(2):146.
Answer to Ferriero et al About “Measurement of the Knee Flexion Angle…”
Dear Editor, I read the letter by Ferriero et al [1] with great interest and I appreciated their valuable comments. I fully agree with their statement that both accelerometer- and photographic-based applications are reliable tools for the knee angle measurement. Indeed, further studies are warranted to comparatively assess the strengths and weaknesses of these two kinds of applications. Our study compared actually the smartphone measurement to a validated, non biased reference measurement technique. We demonstrated that the smartphone application had an acceptable accuracy for the majority of patients. However, the study quoted about the knee joint [2] was a comparison between two different measurement devices. The reference tool for this study was a universal goniometer, which is
449
known to involve possible bias [2–4]. The authors actually demonstrated that there was a good agreement between both measurement techniques, but did not compare these devices to a (supposed…) non biased reference technique. Consequently, they did not demonstrate that the photographic-based application was not biased. After having read their paper, we eventually planned to perform a new study comparing both accelerometer- and photographic-based applications to the navigation reference. Sincerely yours, Jean-Yves Jenny, MD
http://dx.doi.org.10.1016/j.arth.2013.06.013
References 1. Letter Ferriero et al. [E-pub ahead of print]. 2. Ferriero G, Vercelli S, Sartorio F, et al. Reliability of a smartphone based goniometer for knee joint goniometry. Int J Rehabil Res 2012;36(2):146. 3. Lavernia C, D'Apuzzo M, Rossi MD, et al. Accuracy of knee range of motion assessment after total knee arthroplasty. J Arthroplasty 2008;23(6 Suppl 1):85. 4. Lenssen AF, Van Dam EM, Crijns YH, et al. Reproducibility of goniometric measurement of the knee in the in-hospital phase following total knee arthroplasty. BMC Musculoskelet Disord 2007;8:83.
Letter to the Editor: In Response to “Modular Taper Junction Corrosion and Failure: How to Approach a Recalled Total Hip Arthroplasty Implant”
To the Editor: We read the article by Pivec et al on the approach to a recalled total hip arthroplasty with great interest. We applaud the authors for their thoughtful approach to this timely and increasingly difficult problem. While we agree with their overall assessment of the problem, based on our collective and extensive experience with the Rejuvenate stem, and to a lesser degree the ABG, we differ on the aggressiveness of their algorithm for both the diagnosis and treatment. Between our 4 centers, we have implanted 854 Rejuvenate stems and 91 ABGs. We have now reviewed serial metal serum ion levels and MRIs on nearly 85% of the patients. As the authors have, we would like to emphasize that while similar, these are two different stems. The Rejuvenate appears to be exhibiting a higher failure rate at the present time. This may however be simply time dependent, as the average time from index surgery is longer in the Rejuvenate group. The symptoms patients complain of are extremely subtle, most often complaining of groin pain, muscle fatigue, a fullness, achiness, and difficulty sleeping on that side. If one waits until the complaints are of significant pain and noticeable limp, abductor compromise has probably already occurred. One should also be attuned to systemic symptoms such as a rash or neurologic complaints, as these are frequently noted in our patients. We agree with the authors that while the Cobalt level is almost universally elevated, and the Chromium normal, they serve more as a baseline data rather than as absolutes for decision-making purposes. There is no known cutoff above which revision has been recommended. Patients however are very concerned with any elevated levels and time spent counseling them is required. The ESR is not surprisingly typically elevated, while the CRP is typically not. Both should be obtained and aspiration considered if both are elevated and one is worried about superimposed infection, or The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2013.10.028.
450
Letters to the Editor / The Journal of Arthroplasty 29 (2014) 448–451
a revision is pending. This aspiration can give you a definitive diagnosis of either infection, or Adverse Local Tissue Reaction (ALTR). Culture positive infections have been seen in 2–7% of our revisions. Because the patient’s symptoms are often times subtle, and asymptomatic patients have been found to have evidence of particle disease on MRI, we feel that ALL patients deserve a baseline MR imaging study. The study should be performed at a center with MARS capabilities, and by a radiologist with extensive experience with interpreting the images for this diagnosis. An ultrasound can be utilized if an MRI is not available or the patient has a pacemaker. Approximately 67% (range 53%–85%) of our MRIs demonstrated positive findings of particle disease, including effusions, pseudo tumors and tendonopathy. We have not seen an initial MRI study demonstrating positive signs of particle disease or ALTR return to normal. The MRI findings typically progress slowly over the next 3–6 month period. We do not yet have firm data on the rapidity with which it progresses but are looking carefully at that with serial MRIs. Additionally the problem has not been found to correlate with age, gender, time since implantation, weight, or patients' activity level. Because of the above, and until more is known about this unfolding problem, we feel the following should be included in any algorithm pertaining to the ongoing surveillance of these stems: • For asymptomatic patients with reasonable Cobalt levels (b 12 ug/L) and a normal MRI we recommend follow-up and repeating these studies at 6 months. • For asymptomatic patients with MRI findings of a large pericapsular fluid collection and/or a thickened encapsulating rind, a discussion dealing with probable revision should be undertaken with them. A follow-up at 3-4 months with repeat studies is recommended if they decline surgical intervention. • Symptomatic patients with positive findings on MRI, particularly with the presence of pseudo tumors or any soft tissue destruction, should be counseled and encouraged to proceed with prompt revision. • We do not have a cut off for cobalt ion levels above which, in the absence of true systemic symptoms, revision is recommended. The decision for revision is a difficult one, especially in patients with minimal symptoms. Our revision rates for the Rejuvenate between the 4 centers averages 51% (range 36–79%) and we anticipate this to continue to grow. The revision rate for the ABG is at 45%. In every case, significant corrosion at the neck stem junction has been seen in conjunction with variable degrees of ALTR. The revision of the stem is relatively straightforward in our hands with the expectation of good results if performed BEFORE soft tissue destruction occurs. Because of this, we counsel our patients with significant evidence of particle disease on MRI that it is a matter of when rather than if the implant revision will be required. While removal of an ingrown uncemented stem can be challenging, most can be removed with minimal metaphyseal bone loss (Paprosky 1 or 2) and typically without the need for an ETO. Fifteen percent of our patients required an ETO ranging from 1.8 to 45% at the 4 centers. The majority of the ETOs occurred earlier in our learning curve at one center prior to the development of our latest techniques. There were a few greater trochanteric fractures that healed following cabling, and we now prophalactically cable at risk trochanters. A video of the stem removal technique should be released soon. The timing of revision is based on the patient’s symptoms and MRI findings. In earlier disease with only small to moderate amounts of fluid and minimal marginal thickening, a reasonable delay for patient convenience is reasonable. For later stages, with the formation of pseudo tumors, and any compromise of the abductor tendons there is an urgency and revision should be performed in as judicious a manner as possible. Our worst results have been seen in those patients with significant destruction to their abductors. The repair of the hip
abductors is compromised by their poor vascularity secondary to the ALTR response to the corrosion at the head neck junction. This often requires a transfer of the Gluteus maximus and/or Tensor to regain abductor function. We believe all patients with one of these implants should be contacted and brought in for initial surveillance studies as outlined above. Additionally, physicians who are treating patients with this dual modular design need to be vigilant in evaluating their patient’s symptoms, exhaustive and persistent in their work-up, and prompt in their recommendation for revision if the patient has significant symptoms or findings on their MRIs suggestive of particle disease. Joseph F. Davies, William A. Leone, Joseph P. Nessler, Paul G. Perona,
MD MD MD MD
http://dx.doi.org.10.1016/j.arth.2013.10.028
Reply to Letter to the Editor by Davies et al
We thank the authors for their thorough letter concerning our report entitled “Modular Taper Junction Corrosion and Failure: How to Approach a Recalled Total Hip Arthroplasty Implant” (Pivec R, Meneghini RM, Hozack WJ, Westrich GH, Mont MA. J Arthroplasty. 2013 Sep 30. [Epub ahead of print]), which raises several pertinent questions regarding the treatment of these patients. As the authors noted, one of the most important considerations is when to recommend revision surgery for these patients and how to properly balance the risk of peri-operative complications with the risk of future muscle damage if surgery is delayed. This may be particularly challenging in the asymptomatic patient with normal metal ion levels. There was discussion among the co-authors on how to properly approach these patients and whether an MRI is warranted as a baseline test along with plain radiographs, serologic markers, and metal ion levels. Since the clinical experience has varied between the co-authors, it was believed that routine MRIs are something that the surgeon should consider based on their experience, but that there was not enough conclusive data to suggest an absolute recommendation, especially in asymptomatic patients. We did, however, have a consensus that evidence of elevated metal ions and/or symptoms was a clear indication for advanced imaging. The experience described by Davies and colleagues demonstrated that with a baseline MRI, adverse tissue reactions were seen in 67% of patients, which included both symptomatic and asymptomatic patients. It would be interesting to observe what the MRI-positive rate is for asymptomatic patients alone and this represents a future avenue of research. The authors also noted the progressive nature of tissue destruction with progression in all patients over a 3–6 month period, which emphasizes the importance of early intervention in the evidence of even mild muscle damage. This clinical experience led the authors to suggest modifications to our treatment algorithm to include a shorter follow-up period (6 months versus 1 year) in patients with no symptoms, nonelevated metal ions, and a normal MRI. Given the rapidity of tissue damage the authors observed in their cohort, we feel that a more aggressive follow-up period is a reasonable approach.
The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.10.029.
