579905
research-article2015
FAIXXX10.1177/1071100715579905Foot & Ankle InternationalDixon et al
Article
Increased Incidence and Severity of Postoperative Radiographic Hallux Valgus Interphalangeus With Surgical Correction of Hallux Valgus
Foot & Ankle International® 2015, Vol. 36(8) 961–968 © The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100715579905 fai.sagepub.com
Alexis E. Dixon, MD1, Lydia C. Lee, MD1, Timothy P. Charlton, MD2, and David B. Thordarson, MD2
Abstract Background: A previous study has shown an increased radiographic prevalence and severity of hallux valgus interphalangeus (HVIP) after surgical correction of hallux valgus (HV) due to correction of pronation deformity. The purpose of this study was to evaluate the change in pre- and postoperative HVIP deformity with correction of HV with multiple radiographic parameters. Methods: A retrospective chart review identified all bunion surgeries performed at a single center from July 1, 2009, to September 30, 2012. Exclusion criteria included prior bony surgery to the first ray, inadequate films, nonadult bunion, Akin osteotomy, or surgical treatment other than bunion correction. Pre- and postoperative films were reviewed for 2 HV angular measurements and 5 HVIP measurements, which were compared. The angles measured were hallux valgus angle (HVA), first intermetatarsal angle (IMA), hallux interphalangeus angle (HIA), distal metatarsal articular angle (DMAA), proximal phalangeal articular angle (PPAA), proximal to distal phalangeal articular angle (PDPAA), and total distal deformity (TDD). Prevalence of HVIP was analyzed in pre- and postoperative radiographs. A 1-sided Student t test was used to compare continuous data, and a chi-square test was used to compare categorical data. Ninety-two feet in 82 patients were eligible. Results: The average preoperative HV improved with surgery. Preoperative HVA improved from 27 to 11 degrees (P < .001). Preoperative IMA improved from 13.6 to 6.1 degrees (P < .001). HVIP worsened after surgery. Preoperative HIA increased from 7.2 to 13.2 degrees (P < .001). DMAA worsened from 7.3 to 9.2 degrees (P = .001). PPAA worsened from 3.2 to 6.2 degrees. PDPAA worsened from 6.7 to 8.2 degrees (P < .001). The TDD increased from 14.6 to 17.9 degrees (P < .001). The prevalence of HVIP pre- and postoperatively as defined by HIA increased from 26% to 79% (P < .001) and by PPAA from 12% to 46% (P < .001). Conclusion: Initial assessment of preoperative radiographs underestimated HVIP. Postoperative correction of the deformity revealed HVIP that was not obvious preoperatively. Level of Evidence: Level III, retrospective comparative series. Keywords: hallux disorders, forefoot disorder Hallux valgus interphalangeus (HVIP), when seen in conjunction with hallux valgus (HV) deformity, is generally approached as a residual deformity after the major correction of HV proximally.1 Frequently, HV corrective surgery can be performed without surgical correction of HVIP, but a surgeon must be prepared to address the valgus, axial rotation, and excess length via phalangeal osteotomies such as the Akin osteotomy if there is residual deformity.1 One group found that in a group of 54 consecutive patients with moderate to severe HV, 44 patients required an Akin osteotomy to correct residual deformity.7 Preoperative weight-bearing foot radiographs are used in the operative planning of HV corrective surgery. The standard views allow for calculation of the correction needed
and inform the surgeon as to the proper procedure to use. However, the rotational component of the deformity itself can mask the true coronal deformity. That is, pronation of the first ray brings the anteroposterior (AP) portion of the 1
Department of Orthopaedic Surgery, University of Southern California– Keck School of Medicine, Los Angeles, CA, USA 2 Division of Orthopedics, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA Corresponding Author: Alexis E. Dixon, MD, Department of Orthopaedic Surgery, University of Southern California–Keck School of Medicine, 1200 N. State St, GNH 3900, Los Angeles, CA 90033 USA. Email: [email protected]
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first ray out of the plane of the AP radiograph. This is of particular importance more distally, where the phalanges of the hallux may appear as oblique or even lateral on the AP radiograph. Thus, in that situation, the presence of HV would be obscured, as the radiograph is taken parallel to the plane of the HVIP deformity. It has previously been shown that the incidence of HVIP on intraoperative radiographs increases relative to preoperative radiographs after correction of HV deformity with basilar first metatarsal osteotomy and distal soft tissue realignment.7 This prior study showed that incidence and measured severity of HVIP increased on the intraoperative radiographs after correction of the HV deformity in moderate to severe deformity. Thus, the investigators found that many patients required Akin osteotomy for complete deformity correction and that this could not be anticipated preoperatively by radiographic measures. This raises the question of whether there is increased incidence of HVIP postoperatively that may not have been appreciated in intraoperative radiographs. The purpose of this paper was to evaluate whether surgical correction of HV leads to increased postoperative HVIP on weight-bearing radiographs in both prevalence and severity. A secondary outcome was to determine whether the severity of HVIP on postoperative radiographs was predictable by the degree of HV correction. We hypothesized that the rotational correction of HV would lead to an increase in prevalence and severity of HIVP as measured on postoperative radiographs and that increased correction of HV would be correlated with increased HVIP on postoperative radiographs.
Methods All bunion surgeries in adults performed at a single center by 2 attending surgeons from July 1, 2009, to September 30, 2012, were evaluated for inclusion. The surgeries were identified by a Current Procedural Terminology (CPT) code search for all bunion correction surgeries (28290-9). Exclusion criteria included prior bony surgery to the first ray, inadequate films, nonadult bunion, or treatment with a surgery other than the above-mentioned bunion correction surgeries. There were a total of 298 procedures in 295 feet (265 patients) that underwent a bunion surgery in the time period. Those with an Akin osteotomy (28298) were excluded initially by the CPT code but were confirmed by review of postoperative radiographs. Sixty-nine feet were excluded because of performance of Akin osteotomy at the time of surgery. Seventeen were excluded because the surgery performed was not a bony bunion correction (eg, first metatarsophalangeal fusion was performed, not one of the above-mentioned HV surgeries). Twenty-four were excluded because these were not the index procedure on the first ray, which would affect the preoperative angular measurements. Two procedures were outside the date range, despite the CPT search bringing up the subjects. One subject was excluded for being an adolescent. Ninety-four
Figure 1. Hallux valgus angular measurements. All preoperative and postoperative weight-bearing radiographs were assessed for (A) hallux valgus angle and (B) intermetatarsal angle.
were excluded for inadequate pre- or postoperative films. This includes those who had their preoperative radiographs taken at outside facilities that were not uploaded into our system, those who did not have weight-bearing pre- or postoperative films, and those who lacked either pre- or postoperative films. Ninety-two feet in 82 patients were eligible for the study. Films were then reviewed by 2 senior resident orthopedic surgeons matched into foot and ankle fellowships who were not the operating surgeons. The films selected for review were the latest possible preoperative weight-bearing radiograph and the latest possible postoperative weight-bearing radiograph. This radiograph was selected for several reasons. First, the later follow-ups are more likely to be weight-bearing and are taken out of plaster. Second, the previously referenced study by Park et al7 used intraoperative radiographs to demonstrate development of HVIP and we desired to show longer-term results that demonstrated lasting HVIP even after initiation of weight-bearing and, ultimately, healing. Each pre- and postoperative radiograph was reviewed for 2 HV angular measurements and 5 HVIP measurements. Each measurement was done 3 times by each of the 2 orthopedic surgeons. The angles were hallux valgus angle (HVA), first intermetatarsal angle (IMA), hallux interphalangeus angle (HIA), distal metatarsal articular angle (DMAA), proximal phalangeal articular angle (PPAA; also known as distal articular set angle), proximal to distal phalangeal articular angle (PDPAA), and total distal deformity angle (TDD). The HVA was measured as the angle between a line down the shaft of the hallux metatarsal and a line down the shaft of the proximal phalanx, using the midpoint of the shaft at each metaphysis to draw each line (Figure 1A). The IMA was measured as the angle between a line down the shaft of the first and second metatarsals, using the midpoints at each metaphysis as a guide (Figure 1B). The HIA was measured as the angle between the shaft of the distal
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Figure 2. Hallux valgus interphalangeus angular measurements. All preoperative and postoperative weight-bearing radiographs were assessed for (A) hallux interphalangeus angle, (B) distal metatarsal articular angle, (C) proximal phalangeal articular angle, (D) proximal to distal phalangeal articular angle, and (E) total distal deformity angle.
phalanx and the proximal phalanx of the hallux (Figure 2A). The DMAA was measured as the angle between a line down the shaft of the hallux metatarsal and the distal articular surface of the hallux, excluding osteophytes (Figure 2B). The PPAA was measured as the angle between the proximal articular surface of the proximal phalanx of the hallux, excluding osteophytes, and another line up the shaft of the proximal phalanx, using the midpoints of each metaphysis as a guide (Figure 2C). The PDPAA was measured between the proximal and distal articular surfaces of the proximal phalanx (Figure 2D). The TDD was measured as described by Elliot and Saxby4 (Figure 2E). Here, a line was made at the borders of the articular surface of the hallux distal phalanx. A line was made at the midpoint of this line toward the medial edge of the proximal articular surface of the proximal phalanx. The angle between that line and perpendicular to the proximal articular surface was measured.
Statistics The average of each angle measured in each pre- and postoperative film was taken to account for known intra- and interobserver variability in the measurements. The average
of each of the 6 measurements was used for statistical purposes. A Student t test was used to compare average preand postoperative measurements for each angle measured (HVA, IMA, HIA, DMAA, PPAA, PDPAA, TDD). Correlation was calculated between the correction of the HV deformity and change in the measured HVIP measurements. Both the HVA and the IMA were measured against each of the HVIP measurements (HIA, DMAA, PPAA, PDPAA, TDD) to demonstrate whether there was correlation between correction of the HV and measurement of the HVIP. Correlation was defined as “strong” when ±0.5-1.0, “moderate” when ±0.3-0.5, “weak” when ±0.1-0.3, and “none” when ±0.1 or lower correlation. A 1-tailed Student t test was used to compare average pre- and postoperative measurements for each of the angles. Chi-square statistics were used to analyze the difference in incidence of HVIP as measured by HIA, DMAA, and PPAA. A P value less than .05 was considered significant. Results were then stratified by surgical procedure to determine whether some procedures are more likely to cause worsening of HVIP. Analysis of variance (ANOVA) was used to determine whether each measurement for HVIP was different between groups. For those groups where
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Figure 3. Change in angular measurements after hallux valgus corrective surgery. The hallux valgus angle (HVA) and intermetatarsal angle (IMA), measures of hallux valgus, were both improved postoperatively. The hallux interphalangeus angle (HIA), distal metatarsal articular angle (DMAA), proximal phalangeal articular angle (PPAA), proximal to distal phalangeal articular angle (PDPAA), and total distal deformity angle (TDD) were all worsened with surgery that did not address hallux valgus interphalangeus. Error bars demonstrate standard error.
Figure 4. Pre- and postoperative hallux valgus interphalangeus (HVIP) measurements. Each of the quantitative measurements of HVIP increased on postoperative weight-bearing radiographs. Error bars represent standard error. DMAA, distal metatarsal articular angle; HIA, hallux interphalangeus angle; PPAA, proximal phalangeal articular angle; PDPAA, proximal to distal phalangeal articular angle; TDD, total distal deformity angle.
ANOVA was significant for a difference, a 2-sided Student t test was used to evaluate for significant differences between groups, with alpha .05 for significance.
Results The average HVA improved from preoperative 27 ± 9.7 degrees to postoperative 11 ± 8.1 degrees, for a mean improvement of 16 ± 9.5 degrees (P < .001). Preoperative
IMA was 13.6 ± 3.4 degrees and postoperative IMA was 6.1 ± 3.7 degrees, for a mean improvement of 7.7 ± 4.9 degrees (P < .001). The average HIA worsened after HV surgery without an Akin osteotomy (Figures 3 and 4). Preoperative HIA was 7.2 ± 6.6 degrees and postoperative HIA was 13.2 ± 6.0 degrees, for a mean worsening of 6.0 ± 7.7 degrees (P < .001). DMAA also worsened from 7.3 ± 5.63 degrees preoperatively to 9.2 ± 5.5 degrees postoperatively, for a
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Figure 5. Correlation of improvement of hallux valgus angle (HVA) to change in hallux interphalangeus angle (HIA). Improvement in HVA is negatively correlated (R = 0.64) with change in HIA. As correction of HVA increases, the apparent HIA on postoperative weight-bearing radiographs worsens.
mean worsening of 1.9 ± 6.1 degrees (P = .001). This mean angle is still less than the defined abnormal angle of 10 degrees. PPAA worsened from 3.2 ± 2.1 degrees to 6.2 ± 3.6 degrees for a mean worsening of 3.0 ± 3.7 degrees (P < .001). In addition, with an upper limit of normal of 6 degrees, the average postoperative measurement was diagnostic of HVIP. PDPAA worsened from 6.7 ± 3.8 degrees preoperatively to 8.2 ± 4.1 degrees postoperatively. The TDD increased from 14.6 ± 3.7 degrees to 17.9 ± 3.1 degrees, for a mean worsening of 3.3 ± 3.3 degrees (P < .001). Correction of the HVA was strongly correlated to worsening of the HIA (R = –0.64) (Figure 5). Correction of the HVA was moderately correlated to worsening of the TDD (R = –0.40) and the PPAA (R = –0.32). Correction of the HVA was not strongly correlated with change in the DMAA (R = 0.036) or PDPAA (R = 0.030). Correction of the IMA was moderately correlated to worsening of HIA (R = –0.55), PPAA (R = –0.47), and TDD (R = –0.49). It was weakly correlated with improvement of the DMAA (R = 0.22) and worsening of the PDPAA (R = –0.23). The prevalence of HVIP pre- and postoperatively as defined by Gentili et al,5 using measurements of HIA, DMAA, and PPAA, was compared in pre- and postoperative groups; the results are shown in Table 1. Preoperatively, 26% (24/92) had HVIP as defined by HIA greater than 10 degrees; this number increased to 79% postoperatively (73/92) (P < .001). By measurement of DMAA, where normal is less than 10 degrees,10 22% (21/92) had HVIP preoperatively, demonstrating a significant increase in HVIP given that 43% (40/92) had HVIP postoperatively (P = .0029). HVIP as defined by PPAA greater than 6 degrees
Table 1. Prevalence of Hallux Valgus Interphalangeus (HVIP) Pre- and Postoperativelya. Angle Measured
Prevalence of Preoperative HVIP, %
Prevalence of Postoperative HVIP, %
P Value
26 22 12
79 43 46
research-article2015
FAIXXX10.1177/1071100715579905Foot & Ankle InternationalDixon et al
Article
Increased Incidence and Severity of Postoperative Radiographic Hallux Valgus Interphalangeus With Surgical Correction of Hallux Valgus
Foot & Ankle International® 2015, Vol. 36(8) 961–968 © The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100715579905 fai.sagepub.com
Alexis E. Dixon, MD1, Lydia C. Lee, MD1, Timothy P. Charlton, MD2, and David B. Thordarson, MD2
Abstract Background: A previous study has shown an increased radiographic prevalence and severity of hallux valgus interphalangeus (HVIP) after surgical correction of hallux valgus (HV) due to correction of pronation deformity. The purpose of this study was to evaluate the change in pre- and postoperative HVIP deformity with correction of HV with multiple radiographic parameters. Methods: A retrospective chart review identified all bunion surgeries performed at a single center from July 1, 2009, to September 30, 2012. Exclusion criteria included prior bony surgery to the first ray, inadequate films, nonadult bunion, Akin osteotomy, or surgical treatment other than bunion correction. Pre- and postoperative films were reviewed for 2 HV angular measurements and 5 HVIP measurements, which were compared. The angles measured were hallux valgus angle (HVA), first intermetatarsal angle (IMA), hallux interphalangeus angle (HIA), distal metatarsal articular angle (DMAA), proximal phalangeal articular angle (PPAA), proximal to distal phalangeal articular angle (PDPAA), and total distal deformity (TDD). Prevalence of HVIP was analyzed in pre- and postoperative radiographs. A 1-sided Student t test was used to compare continuous data, and a chi-square test was used to compare categorical data. Ninety-two feet in 82 patients were eligible. Results: The average preoperative HV improved with surgery. Preoperative HVA improved from 27 to 11 degrees (P < .001). Preoperative IMA improved from 13.6 to 6.1 degrees (P < .001). HVIP worsened after surgery. Preoperative HIA increased from 7.2 to 13.2 degrees (P < .001). DMAA worsened from 7.3 to 9.2 degrees (P = .001). PPAA worsened from 3.2 to 6.2 degrees. PDPAA worsened from 6.7 to 8.2 degrees (P < .001). The TDD increased from 14.6 to 17.9 degrees (P < .001). The prevalence of HVIP pre- and postoperatively as defined by HIA increased from 26% to 79% (P < .001) and by PPAA from 12% to 46% (P < .001). Conclusion: Initial assessment of preoperative radiographs underestimated HVIP. Postoperative correction of the deformity revealed HVIP that was not obvious preoperatively. Level of Evidence: Level III, retrospective comparative series. Keywords: hallux disorders, forefoot disorder Hallux valgus interphalangeus (HVIP), when seen in conjunction with hallux valgus (HV) deformity, is generally approached as a residual deformity after the major correction of HV proximally.1 Frequently, HV corrective surgery can be performed without surgical correction of HVIP, but a surgeon must be prepared to address the valgus, axial rotation, and excess length via phalangeal osteotomies such as the Akin osteotomy if there is residual deformity.1 One group found that in a group of 54 consecutive patients with moderate to severe HV, 44 patients required an Akin osteotomy to correct residual deformity.7 Preoperative weight-bearing foot radiographs are used in the operative planning of HV corrective surgery. The standard views allow for calculation of the correction needed
and inform the surgeon as to the proper procedure to use. However, the rotational component of the deformity itself can mask the true coronal deformity. That is, pronation of the first ray brings the anteroposterior (AP) portion of the 1
Department of Orthopaedic Surgery, University of Southern California– Keck School of Medicine, Los Angeles, CA, USA 2 Division of Orthopedics, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA Corresponding Author: Alexis E. Dixon, MD, Department of Orthopaedic Surgery, University of Southern California–Keck School of Medicine, 1200 N. State St, GNH 3900, Los Angeles, CA 90033 USA. Email: [email protected]
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first ray out of the plane of the AP radiograph. This is of particular importance more distally, where the phalanges of the hallux may appear as oblique or even lateral on the AP radiograph. Thus, in that situation, the presence of HV would be obscured, as the radiograph is taken parallel to the plane of the HVIP deformity. It has previously been shown that the incidence of HVIP on intraoperative radiographs increases relative to preoperative radiographs after correction of HV deformity with basilar first metatarsal osteotomy and distal soft tissue realignment.7 This prior study showed that incidence and measured severity of HVIP increased on the intraoperative radiographs after correction of the HV deformity in moderate to severe deformity. Thus, the investigators found that many patients required Akin osteotomy for complete deformity correction and that this could not be anticipated preoperatively by radiographic measures. This raises the question of whether there is increased incidence of HVIP postoperatively that may not have been appreciated in intraoperative radiographs. The purpose of this paper was to evaluate whether surgical correction of HV leads to increased postoperative HVIP on weight-bearing radiographs in both prevalence and severity. A secondary outcome was to determine whether the severity of HVIP on postoperative radiographs was predictable by the degree of HV correction. We hypothesized that the rotational correction of HV would lead to an increase in prevalence and severity of HIVP as measured on postoperative radiographs and that increased correction of HV would be correlated with increased HVIP on postoperative radiographs.
Methods All bunion surgeries in adults performed at a single center by 2 attending surgeons from July 1, 2009, to September 30, 2012, were evaluated for inclusion. The surgeries were identified by a Current Procedural Terminology (CPT) code search for all bunion correction surgeries (28290-9). Exclusion criteria included prior bony surgery to the first ray, inadequate films, nonadult bunion, or treatment with a surgery other than the above-mentioned bunion correction surgeries. There were a total of 298 procedures in 295 feet (265 patients) that underwent a bunion surgery in the time period. Those with an Akin osteotomy (28298) were excluded initially by the CPT code but were confirmed by review of postoperative radiographs. Sixty-nine feet were excluded because of performance of Akin osteotomy at the time of surgery. Seventeen were excluded because the surgery performed was not a bony bunion correction (eg, first metatarsophalangeal fusion was performed, not one of the above-mentioned HV surgeries). Twenty-four were excluded because these were not the index procedure on the first ray, which would affect the preoperative angular measurements. Two procedures were outside the date range, despite the CPT search bringing up the subjects. One subject was excluded for being an adolescent. Ninety-four
Figure 1. Hallux valgus angular measurements. All preoperative and postoperative weight-bearing radiographs were assessed for (A) hallux valgus angle and (B) intermetatarsal angle.
were excluded for inadequate pre- or postoperative films. This includes those who had their preoperative radiographs taken at outside facilities that were not uploaded into our system, those who did not have weight-bearing pre- or postoperative films, and those who lacked either pre- or postoperative films. Ninety-two feet in 82 patients were eligible for the study. Films were then reviewed by 2 senior resident orthopedic surgeons matched into foot and ankle fellowships who were not the operating surgeons. The films selected for review were the latest possible preoperative weight-bearing radiograph and the latest possible postoperative weight-bearing radiograph. This radiograph was selected for several reasons. First, the later follow-ups are more likely to be weight-bearing and are taken out of plaster. Second, the previously referenced study by Park et al7 used intraoperative radiographs to demonstrate development of HVIP and we desired to show longer-term results that demonstrated lasting HVIP even after initiation of weight-bearing and, ultimately, healing. Each pre- and postoperative radiograph was reviewed for 2 HV angular measurements and 5 HVIP measurements. Each measurement was done 3 times by each of the 2 orthopedic surgeons. The angles were hallux valgus angle (HVA), first intermetatarsal angle (IMA), hallux interphalangeus angle (HIA), distal metatarsal articular angle (DMAA), proximal phalangeal articular angle (PPAA; also known as distal articular set angle), proximal to distal phalangeal articular angle (PDPAA), and total distal deformity angle (TDD). The HVA was measured as the angle between a line down the shaft of the hallux metatarsal and a line down the shaft of the proximal phalanx, using the midpoint of the shaft at each metaphysis to draw each line (Figure 1A). The IMA was measured as the angle between a line down the shaft of the first and second metatarsals, using the midpoints at each metaphysis as a guide (Figure 1B). The HIA was measured as the angle between the shaft of the distal
Downloaded from fai.sagepub.com at TEXAS A & M INTL UNIV on October 16, 2015
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Figure 2. Hallux valgus interphalangeus angular measurements. All preoperative and postoperative weight-bearing radiographs were assessed for (A) hallux interphalangeus angle, (B) distal metatarsal articular angle, (C) proximal phalangeal articular angle, (D) proximal to distal phalangeal articular angle, and (E) total distal deformity angle.
phalanx and the proximal phalanx of the hallux (Figure 2A). The DMAA was measured as the angle between a line down the shaft of the hallux metatarsal and the distal articular surface of the hallux, excluding osteophytes (Figure 2B). The PPAA was measured as the angle between the proximal articular surface of the proximal phalanx of the hallux, excluding osteophytes, and another line up the shaft of the proximal phalanx, using the midpoints of each metaphysis as a guide (Figure 2C). The PDPAA was measured between the proximal and distal articular surfaces of the proximal phalanx (Figure 2D). The TDD was measured as described by Elliot and Saxby4 (Figure 2E). Here, a line was made at the borders of the articular surface of the hallux distal phalanx. A line was made at the midpoint of this line toward the medial edge of the proximal articular surface of the proximal phalanx. The angle between that line and perpendicular to the proximal articular surface was measured.
Statistics The average of each angle measured in each pre- and postoperative film was taken to account for known intra- and interobserver variability in the measurements. The average
of each of the 6 measurements was used for statistical purposes. A Student t test was used to compare average preand postoperative measurements for each angle measured (HVA, IMA, HIA, DMAA, PPAA, PDPAA, TDD). Correlation was calculated between the correction of the HV deformity and change in the measured HVIP measurements. Both the HVA and the IMA were measured against each of the HVIP measurements (HIA, DMAA, PPAA, PDPAA, TDD) to demonstrate whether there was correlation between correction of the HV and measurement of the HVIP. Correlation was defined as “strong” when ±0.5-1.0, “moderate” when ±0.3-0.5, “weak” when ±0.1-0.3, and “none” when ±0.1 or lower correlation. A 1-tailed Student t test was used to compare average pre- and postoperative measurements for each of the angles. Chi-square statistics were used to analyze the difference in incidence of HVIP as measured by HIA, DMAA, and PPAA. A P value less than .05 was considered significant. Results were then stratified by surgical procedure to determine whether some procedures are more likely to cause worsening of HVIP. Analysis of variance (ANOVA) was used to determine whether each measurement for HVIP was different between groups. For those groups where
Downloaded from fai.sagepub.com at TEXAS A & M INTL UNIV on October 16, 2015
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Figure 3. Change in angular measurements after hallux valgus corrective surgery. The hallux valgus angle (HVA) and intermetatarsal angle (IMA), measures of hallux valgus, were both improved postoperatively. The hallux interphalangeus angle (HIA), distal metatarsal articular angle (DMAA), proximal phalangeal articular angle (PPAA), proximal to distal phalangeal articular angle (PDPAA), and total distal deformity angle (TDD) were all worsened with surgery that did not address hallux valgus interphalangeus. Error bars demonstrate standard error.
Figure 4. Pre- and postoperative hallux valgus interphalangeus (HVIP) measurements. Each of the quantitative measurements of HVIP increased on postoperative weight-bearing radiographs. Error bars represent standard error. DMAA, distal metatarsal articular angle; HIA, hallux interphalangeus angle; PPAA, proximal phalangeal articular angle; PDPAA, proximal to distal phalangeal articular angle; TDD, total distal deformity angle.
ANOVA was significant for a difference, a 2-sided Student t test was used to evaluate for significant differences between groups, with alpha .05 for significance.
Results The average HVA improved from preoperative 27 ± 9.7 degrees to postoperative 11 ± 8.1 degrees, for a mean improvement of 16 ± 9.5 degrees (P < .001). Preoperative
IMA was 13.6 ± 3.4 degrees and postoperative IMA was 6.1 ± 3.7 degrees, for a mean improvement of 7.7 ± 4.9 degrees (P < .001). The average HIA worsened after HV surgery without an Akin osteotomy (Figures 3 and 4). Preoperative HIA was 7.2 ± 6.6 degrees and postoperative HIA was 13.2 ± 6.0 degrees, for a mean worsening of 6.0 ± 7.7 degrees (P < .001). DMAA also worsened from 7.3 ± 5.63 degrees preoperatively to 9.2 ± 5.5 degrees postoperatively, for a
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Figure 5. Correlation of improvement of hallux valgus angle (HVA) to change in hallux interphalangeus angle (HIA). Improvement in HVA is negatively correlated (R = 0.64) with change in HIA. As correction of HVA increases, the apparent HIA on postoperative weight-bearing radiographs worsens.
mean worsening of 1.9 ± 6.1 degrees (P = .001). This mean angle is still less than the defined abnormal angle of 10 degrees. PPAA worsened from 3.2 ± 2.1 degrees to 6.2 ± 3.6 degrees for a mean worsening of 3.0 ± 3.7 degrees (P < .001). In addition, with an upper limit of normal of 6 degrees, the average postoperative measurement was diagnostic of HVIP. PDPAA worsened from 6.7 ± 3.8 degrees preoperatively to 8.2 ± 4.1 degrees postoperatively. The TDD increased from 14.6 ± 3.7 degrees to 17.9 ± 3.1 degrees, for a mean worsening of 3.3 ± 3.3 degrees (P < .001). Correction of the HVA was strongly correlated to worsening of the HIA (R = –0.64) (Figure 5). Correction of the HVA was moderately correlated to worsening of the TDD (R = –0.40) and the PPAA (R = –0.32). Correction of the HVA was not strongly correlated with change in the DMAA (R = 0.036) or PDPAA (R = 0.030). Correction of the IMA was moderately correlated to worsening of HIA (R = –0.55), PPAA (R = –0.47), and TDD (R = –0.49). It was weakly correlated with improvement of the DMAA (R = 0.22) and worsening of the PDPAA (R = –0.23). The prevalence of HVIP pre- and postoperatively as defined by Gentili et al,5 using measurements of HIA, DMAA, and PPAA, was compared in pre- and postoperative groups; the results are shown in Table 1. Preoperatively, 26% (24/92) had HVIP as defined by HIA greater than 10 degrees; this number increased to 79% postoperatively (73/92) (P < .001). By measurement of DMAA, where normal is less than 10 degrees,10 22% (21/92) had HVIP preoperatively, demonstrating a significant increase in HVIP given that 43% (40/92) had HVIP postoperatively (P = .0029). HVIP as defined by PPAA greater than 6 degrees
Table 1. Prevalence of Hallux Valgus Interphalangeus (HVIP) Pre- and Postoperativelya. Angle Measured
Prevalence of Preoperative HVIP, %
Prevalence of Postoperative HVIP, %
P Value
26 22 12
79 43 46
