Title: Foot kinematics in walking on a level surface and on stairs in patients with hallux rigidus before and after cheilectomy

Size: px

Start display at page:

Download "Title: Foot kinematics in walking on a level surface and on stairs in patients with hallux rigidus before and after cheilectomy"

Rosamond Walker
6 years ago
Views:

1 Author's response to reviews Title: Foot kinematics in walking on a level surface and on stairs in patients with hallux rigidus before and after cheilectomy Authors: Benita Kuni (benita@kuni.org) Sebastian I Wolf (sebastian.wolf@med.uni-heidelberg.de) Felix Zeifang (felix.zeifang@med.uni-heidelberg.de) Marc Thomsen (Marc.Thomsen@drk-klinikbb.de) Version: 2 Date: 27 June 2013 Author's response to reviews: see over

2 UniversitätsKlinikum Heidelberg Department Orthopädie, Unfallchirurgie und Paraplegiologie Schlierbacher Landstraße 200a Heidelberg To the Editors-in-Chief of the Journal of Foot and Ankle Research Department Orthopädie, Unfall- Chirurgie und Paraplegiologie Klinik für Orthopädie und Unfallchirurgie Prof. Dr. V. Ewerbeck Ärztlicher Direktor Bereich Bewegungsanalytik Leitung: Dr. rer. nat. S. Wolf Fon +49 (0) Fax +49 (0) Heidelberg, Dear Prof. Menz, Dear Mr. Potter, We are pleased to have the opportunity to resubmit our revised manuscript entitled Foot kinematics in walking on a level surface and on stairs in patients with hallux rigidus before and after cheilectomy to your journal. We would like to thank the editorial team and the two reviewers, Dr. Thewlis and Prof. Nawoczenski, for their interesting and helpful comments. Please find below our responses to each comment. We think that the changes have improved the manuscript considerably. We hereby declare that the corresponding author, Dr. med. Benita Kuni, MD, has permission from all co-authors to resubmit the revised manuscript. Sincerely, Dr. med. Benita Kuni Corresponding Author: Dr. med. Benita Kuni, MD, Department of Orthopedics, Trauma Surgery and Paraplegiology, Heidelberg University Hospital, Schlierbacher Landstr. 200a, D Heidelberg, Germany/Europe, phone: , fax: , benita@kuni.org, benita.kuni@med.uni-heidelberg.de Stiftung Orthopädische Universitätsklinik Heidelberg Schlierbacher Landstraße 200a Heidelberg Fon +49(0) Fax +49(0) orthopaedie.klinikum.uni-

3 Editor General comments: 1. Please carefully review the manuscript for basic grammatical errors. A native speaker reviewed the revised version of the manuscript carefully. The paper was edited using American spelling and grammar. 2. All papers MUST follow the template. The template can found at: Heading hierarchy: JFAR only accepts TWO levels of heading hierarchy. The first level should be indicated with bold Arial 16-point font, and the second level with bold Arial 11-point font (no italics). If you require a third level, this should be indicated by italics in the standard font used in the main text, followed by a colon and no carriage return. We downloaded the template and followed it now. 3. If you are required by referees to change the title or abstract, this must be changed in both the manuscript file and the relevant section in the online submission system. The information in the online submission system is sent to PubMed for indexing, so it is essential that the two match exactly. We will take care of changing the title in both, the uploaded manuscript file and the abstract. 4. In text-referencing: Please ensure that the square bracket references are inserted BEFORE punctuation with a space inserted before the preceeding text, eg: There have been several previous studies in this area [1, 2-5]. We checked all the references and corrected the punctuation. 5. Please replace the word *subjects* and *person* with *participant(s)*. We replaced subjects by control participants or/and persons.

4 Specific comments: Title: Please note the peer-reviewer s comments regarding its accuracy. Please also revise to remove `a prospective controlled study as it gives the impression the study is a controlled clinical trial (when it is not). We changed the title to: Foot kinematics in walking on a level surface and on stairs in patients with hallux rigidus before and after cheilectomy a prospective controlled trial Abstract: Results: Can the authors present values for difference in the main outcomes rather than p-values only. We added the differences of the hallux dorsi-/plantarflexion values to the p-values. Range of motion *in* the first metatarsophalangeal joint Replace *in* with *of*. This was done throughout the abstract and manuscript. Background: The following four changes were done. Line 61: Please replace the word *arthrotic* with *arthritic*. Line 89: replace the word *pre-/postoperatively* with *post-operative* (As mentioned above, the paper was edited by using American spelling and grammar.) Line 93: delete the word *a*. Line 104: hyphenate *MTP-I* Methods: Can the time period of recruitment of participants, both patients and controls, be stated. We stated the time periods as required. Can any body size measures (such as BMI) be included for the participant characteristics. Yes, we added the BMI values for all participants. The following five changes were done. Line 116: insert a space between *II* and *[1]*. Please carefully review entire manuscript and correct any such basic errors. Line 137: Insert the word *a* between *As* and *control* Line 162: please correct this sentence error. Line 192: Can the authors review the term *hallux flexion* and confirm that this is more accurate than *maximum hallux dorsiflexion* etc Line 225: Replace *Kolmogorow* with *Kolmogorov*

5 Results: Lines 239 to 244: There appears to be numerous errors in grammar as well as missing values within brackets. The pain level (AOFAS) was 18.8 ± 13.6 points (p.) (mean ± SD) (with 0 p. = severe, pain almost always present, 40 p. = none) preoperatively and 27.5 ± 7.1 p. postoperatively (according to the numbers available, no significant difference could be detected (= n.s.)). One patient was free of pain; four reported mild, three moderate pain. The activity level (AOFAS) was 5.9 ± 2.2 p. preoperatively and 7.0 ± 2.7 p. postoperatively (n.s.). The checked for errors in grammar and missing values. Preoperatively, the pain level (AOFAS) was 18.8 ± 13.6 points (mean ± SD) and postoperatively 27.5 ± 7.1 points (0 points = sever e pain, almost always present; 20 points = moderate, daily pain; 30 points = mild, occasional pain; and 40 points = no pain); according to the numbers available, no significant difference could be detected (p=0.102). One patient was free of pain; four patients reported mild and three moderate pain. The activity level (AOFAS) was 5.9 ± 2.2 p. preoperatively and 7.0 ± 2.7 p. postoperatively (p=0.083, n.s.). Please report the actual p-value rather than *n.s.* for any non-significant statistical analyses. We added the p-values. Please capitalise the words *Figure* and *Table* throughout the manuscript. This was done. Line 256 (Figure 3): is it possible to present kinematic curves for the sample rather than one participant? Yes, we changed the figure and present the kinematic curve of both groups. Line 283: review *max.(imum)*. This paragraph was removed due to the comments of reviewer 1. Discussion: Lines : please review the sentence for clarity. In stairs descent, the hallux pathology could also be seen, but stairs ascent was not influenced

6 by the hallux rigidus. In all gait conditions, the fore-midfoot pro-/supination was reduced. We splitted the sentence into two sentences: In stairs descent, the hallux pathology could also be seen. Stairs ascent was not influenced by the hallux rigidus. Line 316: Amend the word *The* with *the* Line 317: move the reference *[18]* to after *et al.* rather than at the end of the sentence. Line were removed following the suggestions of the reviewer 1. Line 320: please review this sentence. Nawoczenski et al.[7] found 20 degrees and more gain in dorsiflexion in the MTP-I joint after cheilectomy. We reviewed the sentence. Nawoczenski et al. [6] found a 20-degree gain in dorsiflexion in the MTP-I joint after cheilectomy, while others [7] did not observe any significant improvements in ROM. Line 385: please review this sentence Line 385 was removed following the suggestions of the reviewer 1. Line 411 to 424: Please combine the sections *Clinical implications* and *Conclusions* into *Conclusions* only. We combined both sections into the new paragraph Conclusions. Figure legends: Please remove the *;* from the Figure headings, and capitalise each the initial word of the description. This was changed. 6. Tables: Tables must NOT include any vertical lines. Vertical lines were removed. Table 1: please reduce the amount of abbreviations (spell out *contr.*, *pat.*), and delete (*(MWU) and *Wilcoxon)*) We changed this as suggested.

7 Reviewer 1 1. Please remove all of the data relating to plantar pressure and GRFs these data really do not fit with the aim or hypothesis of the work. They just muddy the water. All data relating to plantar pressure and GRFs were removed. 2. In both the introduction and discussion there are large sections of description of previous work intro: lines 70 77, 89 92; discussion: lines Please rewrite these sections. It is inappropriate to simply state what other work has previously found with no real critical summary. If the reader wants to know more about the specifics they are more than likely to follow the reference trail. Yes, thank you for this critical remark. We removed large descriptive sections and focused on summarizing and relating the information to our purpose and findings. 3. In general, the introduction is far too long. Please shorten it significantly. The introduction was shortened. 4. No consideration is given to the statistical power of the data. I believe that the sample size is small; however, do not believe that this should stop the work getting published. The authors should be aware that the results are really those of a pilot study and should be therefore put into context as such. Yes. Our study needs to be considered as a pilot study. Therefore, we have added this term to be more precise (p 2 line 26, p 4, line 75, p 10, line 245, p 11, line 253, p 14, line 326, p 15, line 359). 5. I remain unconvinced by the Heidelberg foot model. The authors should explain why planar angles are acceptable to use in this work. Can the authors account for any cross-planar talk? It strikes me as though the model doesn t in fact model anything, but instead simply provides a set of simple points to perform

8 some simple trig with. We understand the reluctance of the reviewer as this kinematic model differs from many other more conventional approaches. We have attempted to elaborate on this a bit further in our response to the reviewer and slightly extended the description in the methods section of the manuscript in order to prevent misunderstandings: Typical models assume a series of two or three rigid and rather artificial segments in the foot and allow artificial joints of typically 3 degrees of motion (rotations), which are represented by Euler- or Euler-Cardan angles. However, due to the many rigid segments and articulations in the mid- and forefoot, our approach describes the angular orientations of anatomical landmarks, possibly spanning more than one anatomical joint, rather than relying solely on rigid segment modeling. Such a functional segment can then be described by its relative motion via projection angles defined as the angle between two vectors (or 2Dsegments) in the perspective view along the (single) axis of rotation. As such cross-planar talk in this approach is no different from conventional modeling approaches as there, too, motion is defined in 3D. In the manuscript p 6 lines 146 to 158 have been changed as follows: Unlike typical models which assume a series of two or three rigid and rather artificial segments in the foot and allow artificial joints of typically 3 degrees of motion (rotations) as represented by Euler- or Euler-Cardan angles, the HFMM describes the angular orientations of anatomical landmarks, possibly spanning more than one anatomical joint, rather than relying solely on rigid segment modeling. Such a functional segment is then described by its relative motion via projection angles defined as the angle between two vectors (or 2Dsegments) in the perspective view along the axis of rotation. Consequently, the motion of the ankle complex is described by two axes of rotation accounting for talocrural and subtalar motion via the motion of the three calcaneal markers (CCL, LCL, MCL) and the navicular marker (NAV) with respect to tibial markers (LEP, TTU, SH1, SH2). For the ease of interpretation, the medial arch is defined directly as the angle spanned by the triangle of the markers MCL, NAV, and PMT1. 6. Why were none of the data filtered? This is a fundamental step in almost all data reduction and signal processing. There must be justification for this. Otherwise, the authors must adhere to convention and filter their data.

9 In this point we disagree with the reviewer. In our opinion filtering is not a matter of convention. Filtering of kinematic data obtained by optical 3D motion capture can be performed when the system is used at its limits of spatial or time resolution or optical brightness. This may be the case in foot motion capturing as marker sizes need to be small, the distances between markers are small, and the probability for marker occlusion is large. Consequently, the marker positions may switch or lead to gaps in marker trajectories. However, with adequate hardware and camera setup these weaknesses can be overcome and filtering becomes obsolete. 7. The ROM results and their significance concern me. While there a number of statistically significant results, the magnitude of these results seems very small approx. 2.5 degrees. This is below the measurement accuracy of the systems we use this is independent of the model. When one then considerers the minimal detectable differences associated with most models the magnitude of this difference is meaningless. I would suggest that the authors present the effects sizes along with the p-values to give some context. We do not fully understand the concern of the reviewer. For the most relevant parameter Hallux dorsi/plantarflexion, the differences in ROM between groups are as large as 8.2. This result is both statistically significant and clinically relevant. The standard deviations in ROM (not standard error!) have been proven to be as low as 0.3 (subtalar inversion) and 1.8, the largest for tibiotalar flexion (compare Simon et al). Hence, even some of the small changes between measurements in the order of 2.5 proved to be statistically significant although the change due to surgery can hardly be clinically relevant. Unfortunately, and somewhat misleading, standard deviations of 2-7 for absolute joint angle determination were also given in the methods section. This uncertainty is largely a result of the difficulty in defining an anatomically neutral position - a typical offset problem in foot modeling. Hence, we conservatively decided for all parameters to only interpret full ranges of motion including both directions of motion relative to the neutral position. Here we found standard deviations between 0.3 and 0.8 as stated above. In the methods section p 7 lines , one sentence has been changed accordingly: According to Simon et al. [8] the HFMM parameters show standard deviations between two and seven degrees for absolute angular values due to inaccurate marker placement on the

10 part of the examiner but standard deviations in ROM remain small, at between 0.3 and 1.8. We added the effect sizes (Cohen s d and effect size r) in table Figure two is pointless. Please remove. We removed Figure 2. Reviewer 2 1. For assessment of gait and stairs, self-selected speeds were allowed. Were post-operative speeds matched to pre-operative values for the patient group for each of these activities? It would be helpful to report speeds for each group. Yes, pre- and postoperative speeds matched in the patient group in level walk and in walking up the stairs (please see below). Postoperatively, patients reduced their speed when walking down the stairs as compared to the preoperative speed (p=0.043, Wilcoxon). The operation might have had a negative influence on their sense of security for walking down stairs. We could add these speeds to table 1 of the manuscript. Speed (in m/s) Preoperatively Postoperatively Controls Level / / / Up stairs / / /-0.06 Down stairs / / / For patients walking speeds were lower than for controls in level walking (MWU, preop. p=0.034, postop. p=0.021) and walking down the stairs postoperatively (p=0.004), but not climbing up the stairs (n.s.). However, we do not believe that the higher pace of the control influenced the ROM. 2. The use of the AOFAS Hallux and Lesser Toe outcome scale has been shown to have questionable validity, especially related to activity (see Baumhauer JF et al Reliability and Validity of the American Orthopaedic Foot and Ankle Society Clinical Rating Scale. Foot Ankle Int

11 : ). The assignment of point values to range of motion measurements for hallux function is arbitrary. The weighting of the items 40% to pain, 45% to function and 15% to alignment has also been questioned with regard to its ability to represent important patient outcomes. Perhaps this is one reason that findings were not significant for some of the categories particularly pain and activity. So what do the significant differences in the AOFAS scale really reflect? Many thanks for this reflection about the AOFAS scale. We also felt that this scale did not really adequately distinguish between the different states of the patients. We have discussed that point further p 14 line 333 to p 15 line 350: Although there was no statistical evidence of pain relief, we found an overall improvement in the total AOFAS Scale after the operation, indicating better clinical state. The lack of significant changes in the subcategories pain and activity could be due to the small number of patients. The validity of the AOFAS Hallux Metatarsophalangeal-Interphalangeal Scale has been previously shown to be questionable, especially related to activity [18]. Not all the subcategories are useful for specifying the pathology of hallux rigidus: Since ROM is not differentiated in dorsiflexion and plantarflexion of the MTP-I joint, restriction and changes in the MTP-I joint dorsiflexion are not always well represented. The motion of the interphalangeal joint of the hallux and the stability of the metatarsophalangealinterphalangeal joint are mostly not impaired by hallux rigidus. Therefore, these subcategories do not reflect the changes achieved by cheilectomy, in which osteophytes are always removed. The weighting of the alignment seems to be mostly chosen with respect to hallux valgus patients. Therefore, these subcategories are not suitable for distinguishing the degree of hallux rigidus and quantifying the results of the operative procedure. However, the total scale sum seemed to reflect the state of the patient quite well since the main points are composed of subjectively reported data. 3. Did the investigators measure a starting position and if so, did this change post-operatively? There is some indication that removal of the dorsal osteophytes may create a situation of metatarsal elevation. If this does occur, relative motion between the hallux and 1st metatarsal could appear unchanged. Were any of the other measurements able to capture the metatarsal elevation (eg. forefoot-midfoot pronation/supination during gait?)

12 We thank the reviewer for this critical question and comment. Removal of the dorsal osteophytes may technically have indeed created a situation of metatarsal elevation. We did always measure a static position as a starting point. However, this may not have been an anatomically neutral position, which is a typical offset problem of foot modeling. Hence, we made a conservative decision for all parameters to only interpret full ranges of motion, including both directions of motion relative to the neutral position. For the hallux motion this includes dorsiflexion and plantarflexion independent of the position of the proximal metatarsal segments. The data shown in the former figure 4 (new figure 3) further show that in the case of hallux flexion the absolute angles also appear to be valid as hardly any plantarflexion seems to play a role. Metatarsal elevation may in fact be detected by forefoot-midfoot pronation/supination in our model but the neutral position is not rigorously defined for this parameter either. Hence only ROMs were evaluated. 4. Was the surgery done by the same physician? If not, could this have affected outcomes? Six of the eight patients were operated by the senior author of the paper (four of those together with the first author), one patient by the first author, and one patient by the other coauthor (F.Z.). All three surgeons cooperated closely and followed exactly the same operative procedure, which is documented in the medical reports. No additional soft tissue release or other operative steps were performed. Therefore, we do not believe that the different surgeons were a factor in the outcomes. 5. In Table 1, the authors provide a thorough presentation of the data regarding foot function. Elaboration of these findings, particularly in the case of significant findings and their potential relationship to hallux function is certainly warranted for this Discussion section of the manuscript. We added the following section in the discussion about the significant findings of the segmental foot function analysis. Now, all the significant findings are discussed (p 12, lines ). Furthermore, ROM was not completely restored in the horizontal plane by the operation: The hallux ab-/adduction increased after surgery, but it was still significantly lower than in

13 controls. The osteophytes might not have been the main cause of this restriction, but rather the morphologic changes in the MTP-I joint due to the osteoarthritis. However, the restricted fore-hindfoot ab-/adduction might also be a secondary consequence of the abnormal forefoot kinematics as it did not improve during level walking after the operation. Indeed, the reduced mobility in the sagittal plane seems to cause secondary restrictions in the other degrees of freedom (ab-/adduction and pro-/supination).

FUNCTIONAL METATARSAL LENGTH IN PATIENTS WITH MIDFOOT ARTHRITIS

FUNCTIONAL METATARSAL LENGTH IN PATIENTS WITH MIDFOOT ARTHRITIS Smita Rao, PT, PhD Assistant Professor Department of Physical Therapy New York University Judith F. Baumhauer Department of Orthopedics,