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Patellar Instability Factors in Isolated Medial Patellofemoral Ligament Reconstructions−−What Does the Literature Tell Us?: A Systematic Review Marc A. Tompkins and Elizabeth A. Arendt Am J Sports Med published online March 6, 2015 DOI: 10.1177/0363546515571544 The online version of this article can be found at: http://ajs.sagepub.com/content/early/2015/03/06/0363546515571544

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Clinical Sports Medicine Update

Patellar Instability Factors in Isolated Medial Patellofemoral Ligament Reconstructions—What Does the Literature Tell Us? A Systematic Review Marc A. Tompkins,*y MD, and Elizabeth A. Arendt,*yz MD Investigation performed at University of Minnesota, Minneapolis, Minnesota, USA Background: Many studies have demonstrated good results after medial patellofemoral ligament (MPFL) reconstruction for patients with patellar instability. The applicability of published studies to the clinical decision-making process for the individual patient with patellar instability, however, is not well elucidated. Hypothesis: There is inconsistency in the reporting of preoperative and postoperative variables, which limits the applicability of current studies to patients with patellar instability. Study Design: Systematic review. Methods: A systematic review of the literature was conducted using the search term medial patellofemoral ligament reconstruction to identify studies with cohorts of patients with isolated MPFL reconstruction. A combination of inclusion and exclusion criteria resulted in 24 studies being reviewed for a variety of preoperative demographics, physical examination findings, and imaging findings, as well as postoperative outcomes, including redislocation and responses to subjective questionnaires. Results: A physical examination of lateral patellar translation was reported in 42% of studies, by reporting an apprehension sign (n = 9), reporting quadrant translation (n = 7), or both. For patellar instability factors on imaging, patellar height was reported as a preoperative variable in 75% of studies, and trochlear dysplasia was reported in 83% of studies. The tibial tubercle–trochlear groove distance was reported as a preoperative variable in 42% of studies. The rate of redislocation after index surgery was reported in 92% of studies. Patient-related outcome measures were reported in all of the studies; the Kujala score was the most common. A homogeneous population was selected as part of the authors’ surgical indications for ‘‘isolated’’ MPFL in 67% of studies, and a heterogeneous population was selected in 33% of studies. Conclusion: Current literature on MPFL reconstruction contains diverse methods of recording preoperative and postoperative variables. Most studies report on a homogeneous population, with inconsistent applicability to the broad spectrum of patients with patellar instability. Outcomes reporting in our current literature needs more clarity and consistency regarding reporting methodology to be of value for the treating clinician. Keywords: medial patellofemoral ligament reconstruction; systematic review; preoperative reporting; outcomes

The medial patellofemoral ligament (MPFL) is the major static stabilizer of the patella, resisting lateral patellar translation. When the MPFL is deficient or lax, the patella is at risk for increased lateral translation and possible dislocation. Many different surgical procedures have been employed to address lateral patellar dislocation and the concomitant MPFL injury. A common current approach to patellar stabilization is a reconstruction of the MPFL, which has been described with many different techniques.10 Current literature on MPFL reconstruction includes evidence level 3 and 4 data and demonstrates good

z

Address correspondence to Elizabeth A. Arendt, MD, Department of Orthopaedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R 200, Minneapolis, MN 55454, USA (email: [email protected]). *Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota, USA. y TRIA Orthopaedic Center, Minneapolis, Minnesota, USA. The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. The American Journal of Sports Medicine, Vol. XX, No. X DOI: 10.1177/0363546515571544 Ó 2015 The Author(s)

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outcomes after this procedure.§ Previous systematic reviews involving MPFL reconstruction have evaluated the surgical complications, rehabilitation, and return-tosports levels after this procedure.11,25,35,40 A seminal article on patellofemoral instability outlined 4 instability factors based on imaging and cited a threshold for each instability factor.7 The study argued that each factor beyond the threshold should be normalized if surgical patellar stabilization is performed. It is not known if the addition of an MPFL reconstruction to the surgical armamentarium changes this surgical algorithm or if current published studies on MPFL reconstruction help to answer this question. When trying to define the population that has successful results after any surgical procedure, one needs to detail pre- and postoperative variables, as well as correlate successful surgical outcome with preoperative factors. The purpose of this systematic literature review was to define the population that has a successful (short-term) outcome after isolated MPFL reconstruction. We defined isolated MPFL reconstruction to be soft tissue surgery only, without bony correction, or soft tissue patellar tendon realignments. To this end, the objectives of this literature review were as follows: 1. to report the frequency of preoperative factors, including instability factors, in studies of isolated MPFL reconstructions; and 2. to record reported outcomes, including injury recurrence and patient subjective outcomes tools, for commonality and consistency in study metrics. Upon completion of this review, it is hoped that, based on literature results, one would be able to better predict the population for which an isolated MPFL reconstructive surgery has the best chance of a successful outcome.

resulted in 48 studies. To further enhance the quality of the analysis, we excluded articles from these 48 studies if they were published in a journal with an impact factor of less than 2 (14 studies), involved fewer than 10 patients in the isolated MPFL cohort (4 studies), or involved the same cohort of patients as other studies or were by the same group of authors from the same institution (6 studies). For this last exclusion criterion, the most recent studies were retained. This resulted in a final total of 24 included studies, published in 7 different journals.||

Variables of Interest All studies were evaluated for the following variables:  Demographics: number of patients in cohort, patient’s age at the time of surgical reconstruction, and length of postoperative follow-up  History variables: history of primary patellar dislocation versus recurring patellar instability, mechanism of injury, preoperative patient activity level, participation in preoperative rehabilitation, and prior patellofemoral or other knee procedures  Physical examination variables: Q-angle, patellar glide test, apprehension test, limb version, and systemic laxity factors  Imaging variables: radiographic and magnetic resonance (MR)/computed tomography (CT) imaging variables  Postoperative outcomes: rate of redislocation after surgical stabilization, subjective outcomes scores

Coleman Methodology Scoring In addition to evaluating the studies for variables of interest specific to MPFL reconstruction, we also evaluated the overall study quality using the Coleman methodology score (CMS).5

MATERIALS AND METHODS This systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and MetaAnalyses) guidelines for reporting systematic reviews and meta-analyses.24

Search Strategy A systematic review of the literature was conducted on Medline (PubMed), EMBASE, OVID Medline, CINAHL, and SportsDiscus using the search term medial patellofemoral ligament reconstruction, which generated 303 studies. Exclusion criteria for this analysis included review articles, technique papers, non–English-language articles, and articles on MPFL reconstructions with concomitant trochleoplasties, tibial tubercle osteotomies, long bone osteotomies, or soft tissue procedures realigning the patellar tendon insertion, unless the isolated MPFL reconstruction results were separately reported. These criteria §

References 1, 3, 4, 6, 8, 9, 12, 13, 15, 16, 18-20, 22, 23, 26-29, 32, 36, 38, 41, 42.

RESULTS A total of 24 studies were included in the analysis, with a total of 855 knees from 824 patients. Length of followup ranged from 3 months to 17.2 years, with 17 of 24 (71%) studies reporting a minimum 2-year follow-up (Table 1). The mean age in the studies ranged from 12.2 to 32.5 years, with 19 of 24 (79%) having a mean age between 20 and 30 years (Table 2).

Reporting of Preoperative Variables Patient demographics and historical data are itemized in Table 2. All but 2 studies reported whether patients received surgery after recurrent dislocations compared with after a primary dislocation; 63% included patients with only recurrent dislocations before the index surgery. The mechanism of injury was reported in 28% of studies; when it was reported, most patients (62%) experienced ||

References 1, 3, 4, 6, 8, 9, 12, 13, 15, 16, 18-20, 22, 23, 26-29, 32, 36, 38, 41, 42.

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TABLE 1 Duration of Follow-up by Studya Study, Year Ahmad et al,1 2009 Bitar et al,3 2012 Christiansen et al,4 2008 Deie et al,6 2011 Drez et al,8 2001 Ebied and El-Kholy,9 2012 Gomes,12 2008 Goyal,13 2013 Hinterwimmer et al,15 2013 Howells et al,16 2012 Kang et al,18 2013 Kita et al,19 2012 Kohn et al,20 2013 Ma et al,22 2013 Matthews and Schranz,23 2010 Nelitz et al,26 2013 Nomura and Inoue,27 2006 Nomura et al,28 2007 Panni et al,29 2011 Ronga et al,32 2009 Sillanpaa et al,36 2008 Steiner et al,38 2006 Wagner et al,41 2013 Witonski et al,42 2013

Patients (Knees) Recruited, n

Patients (Knees) With Follow-up, n

Length of Follow-up, y, Average (Range)

21 21 44 29 (31) 19 21 (25); 16 (17) minus tibial tubercle 24 39 19 201 (219); 188 (206) minus tibial tubercle 90 71 15 32 21 (25) 22 12 NR (39) 48 (51) 28 18 36 50 19

20 21 44 29 (31) 15 21 (25)b

2.6 3.2 1.8 3.2 2.6 2.8

(2.0-3.3) (2.0-4.0) (1.0-2.7) (2.0-5.0) (2.0-3.6) (minimum, 2.0)

24 32 19 193 (211)b

4.4 3.2 1.3 1.3

(2.5-5.9) (1.0-5.7) (minimum, 1.0) (0.5-3.5)

82 24 (25) 15 32 21 (25) 21 12 22 (24) 45 (48) 28 15 34 50 10

2.0 1.1 2.0 3.3 2.6 2.8 4.2 11.9 2.8 3.1 10.1 5.5 NR NR

(2.0) (0.5-2.2) (2.0) (2.0-4.6) (0.3-7.3) (2.0-3.6) (3.1-5.6) (8.5-17.2) (2.0-4.5) (2.5-4) (8.0-13.0) (2.0-10.8) (1.0-2.0) (minimum, 2.0)

a

NR, not reported. Total group reported on at follow-up.

b

atraumatic injury, without a clear definition of this term. The preoperative activity level was discussed in 52% of studies. The Tegner activity scale was the most common activity scale reported, with the majority of patients functioning at Tegner level 3 preoperatively. Although 48% of studies reported whether patients had undergone preoperative rehabilitation, length and type of rehabilitation was mentioned in only 7 studies. Prior procedures were reported in 68% of studies. Physical examination variables are itemized in Table 3. A physical examination of lateral patellar translation was reported in 42% of studies, either by reporting an apprehension sign (9 studies) or by reporting quadrant translation (7 studies), or both. The presence of generalized ligamentous laxity or connective tissue disease was reported in 33% of studies, with the majority of included patients having no abnormalities. Imaging variables are itemized in Table 4. Of the 24 studies included, imaging was defined in 92%; measurements were made on plain radiographs in 19 studies and slice imaging (MR or CT) in 12 studies. Two studies did not comment on the type of imaging used. With reference to specific patellar instability factors, patellar height was measured and reported as a preoperative variable in 75% of studies, with 4 different measurement schemes to measure patellar height. For trochlear dysplasia, 83% of

studies reported this as a preoperative variable, with 4 different classification systems used. Of the 12 studies that reported on slice imaging preoperatively, the tibial tubercle–trochlear groove (TT-TG) distance was reported as a preoperative variable in 10 studies; the Q-angle was used in 50% of the remaining studies that did not report on TT-TG distance.

Reporting of Postoperative Variables The rate of redislocation and patient-related outcome measures are itemized in Table 5. The rate of redislocation after index surgery was reported in 92% of studies. The redislocation rate was 1% (mean, 0.36%; range, 0%-3%). Many studies included recurrent subluxation as distinct from frank dislocation, which was variably defined. Patient-related outcome measures were reported in all of the studies; the Kujala score was the most common subjective outcome measure, used in all studies.

Study Population Composition In the majority of articles (16/24; 67%), a homogeneous population was selected as part of the authors’ surgical indications for isolated MPFL (Table 4); that is, exclusion criteria omitted patients with excessive anatomic factors

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TABLE 2 Patient Demographics and Historical Data by Studya Recurrent Dislocation Age at Surgery, Before MPFL y, Mean (Range) Reconstruction, n (%)

Study, Year Ahmad et al,1 2009 Bitar et al,3 2012 Christiansen et al,4 2008 Deie et al,6 2011

Drez et al,8 2001 Ebied and El-Kholy,9 2012 Gomes,12 2008 Goyal,

13

2013

23 (11-43)

Activity Levelb

22 (12-47)

44 (100)

Not noted

Not measured

No

Yes

22.2 (12-34)

31 (100)

Traumatic were excluded

Not measured

No

No prior procedure

22 (14-52) NR

11 (73) NR

All traumatic Not noted

Tegner: 6.8 Not measured

Yes Yes

No No prior procedure

Not noted

No activity scale, just verbally Not measured

No

No

Injuries present; no details

No

No prior procedure

No injuries present

Not measured

No

6 had prior procedure

Injuries present; no details (K-L grades \2 or \3 focal defects) Osteochondral defect (n = 22) and K-L grade 2-4 changes (n = 22) Injuries present; no details (Outerbridge \grade 3) 95% had some degree of Outerbridge PF chondral change No injuries present

19.3 (16-24) 25 (10-48)

Hinterwimmer et al,15 2013

23 (16-47)

Howells et al,16 2012

26 (16-49)

NR



Not noted

Tegner: 3.6

Yes

No prior procedures

All traumatic

Not measured

No

No

Concomitant Injuries 80% with chondral defects in PF joint Injuries present; no details Trochlear dysplasia (n = 12) Injuries present; no details (.K-L grades 3 in PF and 2 in tibiofemoral excluded) Chondromalacia No injuries present

23.95 (12-37)

18 (90)

Mechanism of Injury

Prior Procedures: Proximal Reconstruction Preoperative or Distal Realignment Rehab (Not Lateral Release)

27 (84) ‘‘recurrent 5/32 were acute patellar instability’’ traumatic 19 (100) Traumatic in 6; atraumatic in 13 141 (67)

Traumatic in 50; Pre-Tegner scores atraumatic in 141 not given

No

30 had prior PF realignment

90 (100)

Not noted

Not measured

Yes

No

22.7 (13-43)

25 (100)

Not noted

Not measured

No

No

Kohn et al,20 2013

22 (13-46)

15 (100)

Not noted

Tegner: 2

No

Ma et al,22 2013

28.4 6 4.2

32 (100)

Not noted

Tegner: 3

No

All had a prior procedure of some sort No

Matthews and Schranz,23 2010 Nelitz et al,26 2013

24 (17-44)

25 (100)

Not noted

Tegner: 3

No

No

12.2 (10.3-13.9)

21 (100)

Not noted

Tegner: 6 (range, 3-9)

Yes

24.8 (13-49)

12 (100)

Not noted

Not measured

No

4 had prior medial reefing 8 with chondral lesions, but only 2 required intervention (microfracture) No prior procedure Injuries present; no details

22.5 (13-48)

24 (100)

Not noted

Not measured

No

2 with previous proximal realignment

Panni et al,29 2011

28 (16-60)

48 (100)

Not noted

All played at least recreational sports

Yes

No

Ronga et al,32 2009

32.5 (19-40)

28 (100)

Not noted

No activity scale, just verbally

Yes

Yes

Sillanpaa et al,36 2008 Steiner et al,38 2006

20.2 (19-22)

15 (100)

Not noted

Not measured

No

No prior procedure

19 (56) with 1 dislocation

Not noted

Tegner: 3.1 6 1.6

No

No injuries present

50 (100) ‘‘chronic PF instability’’

Not noted

No

9 (90); 1 (10) with \5 dislocations

Posttraumatic

Measured but pre-Tegner scores not given Not measured

9 had prior procedure; more than just arthroscopy No prior procedure

No

No prior procedure

No injuries present

Kang et al,18 2013 Kita et al,

19

2012

Nomura and Inoue,27 2006 Nomura et al,28 2007

Wagner et al,41 2013 Witonski et al,42 2013

28.9

27

19 6 6

27.2 (18-42)

No injuries present (did not state MRI findings) Injuries present; no details

21/22 knees observed at arthroscopy had Outerbridge grade 2-4 changes in the PF joint Outerbridge grade 1 in 12 knees, grade 2 in 19, grade 3 in 16, grade 4 in 4 knees Degenerative joint disease (n = 10) or osteochondral lesion \15 mm (n = 11) Injuries present; no details

No injuries present

a b

K-L, Kellgren-Lawrence grading scale; MPFL, medial patellofemoral ligament; MRI, magnetic resonance imaging; NR, not reported; PF, patellofemoral. Any activity level was recorded preoperatively, but it was unclear if it is preinjury.

based on physical examination and/or imaging criteria.{ The most common exclusion criteria were high-grade dysplasia (21%) and patella alta (21%), followed by increased

{

References 4, 6, 8, 9, 12, 13, 15, 18, 20, 22, 23, 27, 29, 32, 38, 42.

quadriceps vector (elevated Q-angle [25%] or increased TT-TG distance [29%]). The minority of papers (8/24, 33%) included a heterogeneous population within their study cohort.1,3,16,19,26,28,36,41 In particular, patients with anatomic imaging factors above threshold values were included, specifically patella

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TABLE 3 Preoperative Physical Examination Findings by Studya Study, Year Ahmad et al,1 2009 Bitar et al,3 2012 Christiansen et al,4 2008 Deie et al,6 2011

Apprehension or Translation

Femoral Rotation/Anteversion/ Connective Tissue

Q-Angleb

Mean, 3.5 Q lateral translation; 30% with generalized all had apprehension ligamentous laxity

Mean, 18° (range, 12°-25°)

18/44 had apprehension and lateralizationc 1 had apprehensionc

Abnormal in 3 patients, defined as 20° (F) and 15° (M) Excluded congenital and habitual dislocators

Drez et al,8 2001 Ebied and El-Kholy,9 2012

Normal (\15°) Abnormal/normal; TT-TG distance, 15 6 4 mm Gomes,12 2008 Genu valgus on examination (no more specifics) Goyal,13 2013 2 with hip anteversion, 1 with Abnormal/normal; 1 patient with TTcongenital talipes equinovarus TG distance = 15 mm, 4 with valgus knee, no other details Hinterwimmer et al,15 2013 All had increased lateral Excluded femoral anteversion Normal; TT-TG distance \20 mm, translation with apprehension .20, tibial torsion .40 valgus \5° Howells et al,16 2012 Normal; TT-TG distance \18 mm Kang et al,18 2013 All 82 normalc Normal; TT-TG distance \20 mm, Q-angle \20° (F), \17° (M) Kita et al,19 2012 Apprehension present pre-op in 71 of 71; post-op 3 of 25 Kohn et al,20 2013 All showed apprehension 5 patients received distal Abnormal/normal, TT-TG distance not up to 30° osteotomy for perceived stated on any patient; 4 received rotational issues; values not relateralization of TT because of defined (patients excluded prior overmedialization and were from analysis) excluded from analysis Ma et al,22 2013 Apprehension at 30° present Excluded femoral anteversion Normal, TT-TG distance \15 mm, pre-op in 27 of 32; post-op .35°, other ligament injury valgus \5° 0 of 32 Matthews and Schranz,23 2010 Normal, TT-TG distance \15° Apprehension present pre-op in Excluded anteversion .40°; TT-TG distance: mean, 16 mm (range, Nelitz et al,26 2013 21 of 21, post-op 3 of 21. no ligamentous laxity on 11-22 mm), 3 patients with TT-TG distance .20 mm; excluded valgus Positive J-sign present pre-op all patients in 16 of 21, post-op 3 of 21 .9° Nomura and Inoue,27 2006 Apprehension pre-op measured Normal (\25°) but not reported, post-op 0 of 12. Hypermobility pre-op ‘‘severe’’ in 12 of 12, post-op ‘‘mild’’ in 2 of 12 Nomura et al,28 2007 5 of 24 knees positive for Mean, 18.7° (range, 15°-25°) apprehensionc Panni et al,29 2011 Excluded positive J sign; Normal, TT-TG distance \20 mm, Qpossible to dislocate patella at angle \20° (F), \17° (M), valgus \7° time of surgery in 15 of 51 knees, remaining 36 had positive glide test Ronga et al,32 2009 Minimum 2 quadrant Normal, Q-angle \20°, valgus \7° translation Sillanpaa et al,36 2008 Collected but not reported Steiner et al,38 2006 Positive stress radiographs, Mean, 16.6° (asymptomatic side: 16.4°) positive apprehension, instability on EUA Wagner et al,41 2013 8 patients with TT-TG distance .20 mm Witonski et al,42 2013 Excluded femoral anteversion Normal and generalized laxity a

Total group reported on at follow-up. EUA, examination under anesthesia; F, females; M, males; TT-TG, tibial tubercle–trochlear groove. These data are included in both Tables 3 and 4 because some studies used physical examination findings to discuss extensor mechanism alignment, while others used imaging findings or both. c Postoperative physical examination finding. b

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TABLE 4 Preoperative Imaging Findings by Studya Study, Year

Homogeneous Cohort

Ahmad et al,1 2009

No Results not stratified by anatomic risk factors

Bitar et al,3 2012

Christiansen et al,4 2008

No Results not stratified by anatomic risk factors Yes

Deie et al,6 2011 Drez et al,8 2001

Yes Yes 9

Ebied and El-Kholy, 2012

Yes

Gomes,12 2008

Yes

13

Yes

Trochlear Dysplasia

I/S ratio: 1.1 (range, 0.7-1.5); 4 patients with ratio .1.2 Blackburne-Peel ratio: 1.0 (range, 0.6-1.4); 6 patients with ratio .1.0 I/S and Blackburne-Peel ratios: discussed height as yes/no; 3 had yes

Sulcus angle: 137.3° (range, 119°-148°) Trochlear depth: 8.0 mm (range, 5-10 mm)

Blackburne-Peel ratio: 0.93 (range, 0.68-1.25)/0.92 (range, 0.69-1.19) I/S ratio: Measured preoperatively; no values reported pre- or postoperatively

Positive crossing sign: 7 patients Positive trochlear bump: 6 patients Trochlear depth \4 mm: 3 patients Trochlear angle .160°: 12 patients Patients with TD underwent medial TTT

Sulcus angle: 141° 6 5°

50% stated to have trochlear dysplasia but no details given Dejour \grade C

No Results not stratified by anatomic risk factors

Patella trochlear index \12.5%: 34 knees. Of these, 5 underwent simultaneous distal TTT

Kang et al,18 2013

Yes

I/S ratio: 1.0 6 0.1 (n = 40) and 1.1 6 0.1 (n = 42). Excluded patients with I/S ratio .2.1

Normal, mild (shallow TG), moderate (flat surface), or severe (domed trochlear shape) Moderate TD in 126 knees (58%), mild TD in 77 (35%), normal in 16 (7%) Excluded: sulcus angle .145° and patellar dysplasia Wiberg grades IV and V

Kita et al,19 2012

I/S ratio: 1.1 (range, 0.8-1.4)/1.1 (range, 0.8-1.4)c

Kohn et al,20 2013

No Results not stratified by anatomic risk factors Yes

Ma et al,22 2013

Yes

Matthews and Schranz,23 2010 Nelitz et al,26 2013

Yes No Anteversion .40° was an exclusion criterion Results stratified by anatomic risk factors Yes

Hinterwimmer et al, Howells et al,

16

15

2013

2012

Nomura and Inoue,27 2006

Nomura et al,28 2007

Yes

Excluded: sulcus angle .150°

I/S ratio: 1.2 (range, 1.0-1.3); 2 patients with I/S ratio .1.2

Excluded: Dejour types B and C Dejour types: A (n = 1), B (n = 10), C (n = 4), D (n = 6)

I/S ratio: 1.08 (range, 0.98-1.23)/1.06 (range, 0.96-1.17)c

Sulcus angle: 149.4° (range, 133°163°)/149.8° (range, 133°-164°)c

I/S ratio: 1.13 (range, 0.77-1.42)/1.09 (range, 0.75-1.42)c

Sulcus angle 148.8° (range, 138°-173°)/ 143.5° (range, 130°-170°)c; 2 patients with sulcus angle .160° Excluded: Dejour types B, C, D; Wiberg grades IV-V; sulcus 145°

Panni et al,29 2011

No Results not stratified by anatomic risk factors Yes

Ronga et al,32 2009

Yes

I/S ratio: 1.1 6 0.2/1.1 6 0.2c; excluded patients with an I/S ratio .1.2

Excluded: trochlear angle .145°, Wiberg grades IV-V Trochlear angle: 132° 6 19°

Sillanpaa et al,36 2008

No Results not stratified by anatomic risk factors (all patients active military service members) Yes

I/S ratio: 1.36 (range, 1.04-1.75)c

Sulcus angle: 145° (range, 125°-166°)c

I/S ratio: mean, 1.16; excluded ‘‘significant patella alta’’

No Results stratified by anatomic risk factors Yes

I/S ratio: 1.30 6 0.20; 58% with I/S ratio .1.2

Sulcus angle (correlated to H. Dejour type): type I = 145.4°, type II = 148.1°, type III = 153.8° All patients with positive TD, number of TD by grade not stated H. Dejour type: 2% normal, 42% type I, 42% type II, 14% type III

Steiner et al,38 2006

Wagner et al,41 2013

Witonski et al,42 2013

a

I/S ratio: Excluded patella alta and patella baja

MR in 18/20 patients Q-angle: 18° (range, 12°-25°)

3 with Q-angle .15° (M) and .20° (F) 18 underwent medial TTT, not included in our tables

Congruence angle: 6° 6 3° TT-TG distance: 15 6 4 mm Genu valgus on examination (no more specifics) 1 with TT-TG distance = 15 mm, 4 with valgus knee (no other details) Excluded: TT-TG distance .15 mm and valgus .5° Excluded: TT-TG distance .18 mm (TT-TG hard to evaluate in patients with TD. Patients with TT-TG .18 mm are rare) Excluded: Q-angle .20° (F), .17° (M); also TT-TG distance 20 mm TT-TG distance: 40 patients 14.6 6 1.9 mm and 42 patients 14.0 6 1.8 mm

Sulcus angle: 147.7° (range, 130°-170°)

Mean Caton-Deschamps index of 1.23 (contains some patients with patella alta, not excluded)

I/S ratio: 1.1 (range, 0.8-1.19)/1.06 (range, 0.75-1.16)c; excluded patients with I/S ratio 1.2

TT-TG Distance/Valgus/Q-Angleb

Excluded Q-angle .15°

I/S ratio: 1 patient specifically stated to have alta

Goyal,

2013

Patellar Height

Excluded trochlear dysplasia

4 received relateralization of TT because of prior overmedialization; TT-TG distance not stated Excluded: TT-TG distance .15 mm, valgus .5° TT-TG distance: 12.5 6 1.4 mm Excluded TT-TG distance .15 mm Excluded: valgus .9 TT-TG distance: 16 mm (range, 11-22 mm) 2 patients with TT-TG distance .20 mm Excluded: Q-angle .25° Q-angle: 20.0° (range, 15°-25°)/21.7° (range, 15°-28°)c Q-angle: 18.7° (range, 15°-25°)

Excluded: Q-angle .20° (F) and .17° (M) Valgus  7° TT-TG distance 20 mm Excluded: Q-angle .20°; valgus .7°; positive J-sign; TT-TG distance 20 mm Q-angle: 13.5° 6 3.8°

Q-angle: 16.6°

Patellar tilt: 16.1°/11.2°c TT-TG distance: 15.2 6 5.2 mm (20% .15 mm, 16% .20 mm) Excluded: abnormal Q-angle, external tibial torsion

F, female; I/S, Insall-Salvati; M, male; MR, magnetic resonance; TD, trochlear dysplasia; TTT, tibial tuberosity transfer; TT-TG, tibial tubercle–trochlear groove. These data are included in both Tables 3 and 4 because some studies used physical examination findings to discuss extensor mechanism alignment, while others used imaging findings, or both. c Postoperative imaging finding. Downloaded from ajs.sagepub.com at UCSF LIBRARY & CKM on April 21, 2015 b

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TABLE 5 Subjective Outcome Tools and Recurrence Rate by Studya Redislocation/ Subluxation

Study, Year

Kujala Score, Preop/Postop

Tegner Score, Preop/Postoperative

Ahmad et al,1 2009 Bitar et al,3 2012

0

49.9/88.2

0

Christiansen et al,4 2008 Deie et al,6 2011

1 dislocation/ 3 subluxation 0 (1 redo after 3 y for medial instability, resolved) 1 dislocation/ 1 subluxation NR

NR/88.9 (range, 62100) 46 (range, 12-67)/84 4 (range, 1-9) (range, 62-100) 64 (range, 35-70)/94.5 (range, 79-100)

Drez et al,8 2001 Ebied and El-Kholy,9 2012 Gomes,12 2008 Goyal,

13

NR/1 subluxation

2013

0

Hinterwimmer et al,15 2013

0

Howells et al,16 2012

0

Kang et al,18 2013

0

3.6/5.6

NR/88.6 (range, 57100)

Kohn et al, Ma et al,

22

20

2013

2013

0 0 NR

Matthews and Schranz,23 2010 Nelitz et al,26 2013

0

Nomura and Inoue,27 2006 Nomura et al,28 2007

0

Panni et al,29 2011

0

Ronga et al,

32

2009 36

Sillanpaa et al, 2008 Steiner et al,38 2006 41

0

1 dislocation/NR

3 dislocation/NR 1 dislocation/ 2 subluxation 0

Wagner et al, 2013 1 dislocation Witonski et al,42 2013 0

Fulkerson Score, Preop/Postop

49.5/88.7

6.8/6.4 (range, 1-10)

IKDC Score, Preop/Postop

‘‘ADL’’ 50.1 and 50.6/ 72.8 and 70.3 49.3 (range, 23-62)/ 91.3 (range, 73100) NR/92 (range, 69100) 55.4 (range, 29-85)/ 81.69 (range, 31100) Mean: 52.5/91.3

NR/93 (range, 80-100)

NR/5 (range, 3-7)

53.4 (range, 27-82)/ 83.0 (range, 17-100)

45.98 (range, 26-64)/ 75.12 (range, 18100)

Mean: 50.3/88.4

51.2 6 6.2 (n = 40) and 50.3 6 5.8 (n = 42)/92.3 6 3.9 (n = 40) and 88.4 6 6.8 (n = 42)

73 (range, 66-82)/94.5 (range, 79-100) 58 6 17.3/91 6 17.4 2 (range, 1-5)/6 (range, 3-7) 54 (range, 46-63)/87 3 (range, 1-5)/5 (range, 78-100) (range, 3-8) NR/87 (range, 553 (range, 0-6)/4.4 100) (range, 1-7) 6 (range, 3-9)/5.8 72.9 (range, 37-87)/ (range, 3-9) 92.8 (range, 74100) 56.3 (range, 29-82)/96 (range, 84-100) 63.2 (range, 26-85)/ 94.2 (range, 76100) 56.7 6 17.7/86.8 6 14.4 45 6 17/83 6 14 NR/88.0 (range, 57100) 53.3 6 10.2/90.7 6 9.0 70 6 23/87 6 13 59.7 (range, 11-81)/ 84.4 (range, 56-98)

Postop: 19 excellent, 5 good, 1 fair

Postop: 8 excellent, 10 good, 1 fair

Postop mean: 6.0 (M), 4.78 (F) NR/95.9 6 4.7 (n = 40) and 91.3 6 9.7 (n = 42)

Insall Grade

42.1/82.3

54 6 2/81 6 2

53.5 6 5.6 (n = 40), 52.5 6 5.5 (n = 42)/ 95.9 6 4.7 (n = 40), 91.3 6 9.7 (n = 42) Kita et al,19 2012

Lysholm Score, Preop/Postop

55.5 6 14.0/86 6 17.3

57.6 6 19.6/88.1 6 16.2

59.2 6 21.8/90.1 6 14 Cincinnati 52 6 19/89 6 21

NR/4 (range, 2-8) 3.1 6 1.6/5.1 6 1.6

52.4 6 12.6/92.1 6 8.4

Collected but NR

a ADL, activities of daily living; F, female patients; IKDC, International Knee Documentation Committee; M, male patients; NR, not reported; Postop, postoperative; Preop, preoperative.

alta, increased TT-TG distance, and high-grade trochlear dysplasia. Only 2 of the studies with a heterogeneous population reported an outcome metric in relation to preoperative variables, in particular preoperative anatomic imaging factors.26,41 For those with patella alta, the Insall-Salvati ratio was .1.2 in 2 of 21 patients in Nelitz

et al26 and 29 of 50 patients in Wagner et al.41 There were 2 of 21 patients in Nelitz et al with excessive (.20 mm) TT-TG distance and 8 of 50 patients in Wagner et al. In the other 6 studies with a heterogeneous population, only a very small portion of the patient group had ‘‘excessive’’ anatomic factors.

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TABLE 6 Coleman Methodology Scoresa Study Mean Follow- No. of Surgical Study Diagnostic Procedure Rehabilitation Outcome Assessing Subject Size up, mo Procedures Type Certainty Description Description Criteria Outcomes Selection Mean SD

4.21 2.98

4.04 0.68

6.75 2.3

5.42 3.24

2.21 1.56

4.79 0.15

8.33 1.18

5.71 0.91

5.29 1.92

6.75 2.3

Total 53.5 8.13

a

From Coleman et al.5

Coleman Methodology Scoring The mean CMS5,17,34,39 was 53.5 6 8.1 (Table 6).

DISCUSSION The purpose of published studies is to evaluate outcomes to ultimately help make clinical decisions. Published studies on isolated MPFL reconstructions define a relatively homogeneous population that appears to have successful outcomes for this surgical technique. Our systematic review reports a mean dislocation rate after surgery of 1%, (range, 0%-3%) and satisfactory patient subjective outcomes. The seminal study by Dejour et al7 remains the largest follow-up in our literature on surgically treated patients with recurrent lateral patellar dislocations. These authors laid the foundation for the surgical approach to patellofemoral instability, which includes objective imaging parameters and surgical correction of each instability factor above a defined measurement threshold. More recently, an MPFL reconstruction has been added to this surgical algorithm, which provides a stronger and more anatomic medial check rein that guards against lateral patellar translation. A clinical enigma remains, however, when defining the patient for whom an MPFL reconstruction as an isolated procedure would provide consistent success. In particular, what are the upper thresholds of imaging parameters that would allow for a satisfactory clinical outcome without injury recurrence when doing an MPFL reconstruction without bony correction? To answer this question, we need published studies to include evaluation and documentation of preoperative physical examination and imaging factors, as well as relate these factors to outcome measures. Current literature on isolated MPFL reconstruction, however, contains a paucity of patients with anatomic instability factors above the previously established thresholds laid down by Dejour et al,7 thus giving inadequate data to allow for evidence-based surgical decisions on those patients with abnormal anatomic indices. Those studies that include a heterogeneous population, particularly with regard to anatomic imaging factors (ie, patella alta .1.2, increased quadriceps vector without correction, high-grade trochlear dysplasia), have too few numbers to be able to make clinical treatment decisions based on published outcomes. The 2 studies that did stratify their preoperative anatomic factors with outcome metrics discussed

some concern. Nelitz et al26 found that some patients with high-grade dysplasia continue to display a positive apprehension sign with lateral patellar translation and opined that high-grade trochlear dysplasia might be considered a risk factor for inferior results of MPFL reconstruction in skeletally immature children and adolescents. Wagner et al41 found a negative relationship between trochlear dysplasia and outcomes. However, the numbers reported remain small. Patients with recurrent lateral patellar dislocation each have a combination of risk factors that may make it difficult to assess an individual factor impact on clinical results. However, analyzing risk factors according to classification is necessary to generate a treatment plan. The limitation of the current literature is that there is no consistency in reporting preoperative variables in a meaningful way, limiting the potential to relate these to postoperative outcomes. Perhaps the best example of this inconsistency is trochlear dysplasia. Four different classifications are reported (ie, H. Dejour 3-item classification, D. Dejour 4-item classification, trochlear depth, and sulcus angle with upper measurement limits defining trochlear dysplasia variably defined). Earlier studies may not have had the advantage of slice imaging (MR or CT imaging) to aid in the assessment of the patellar instability patient; current literature has more sophisticated and accepted definitions of trochlear dysplasia that offer better clarity on this dysplastic feature than the sulcus angle.2,31,33 The subjective outcome questionnaires that best profile postoperative evaluation of patients with patellar instability are not well defined, with (historically) the most commonly used scale being the Kujala pain scale.21 As its name implies, this scale was designed to document pain in the patellofemoral compartment. While patellar instability certainly can be accompanied by pain, the Kujala scale does not fully capture the subjective difficulties of the patients with patellar instability. Patient-reported outcome scales designed specifically for patellar instability are a recent addition to knee outcomes scales; the authors suggest inclusion of these in future reporting on MPFL reconstruction outcomes.14,37 Clinical decision based on evidence-based medicine would be helped by the development of consensus guidelines for pre- and postoperative factors to aid the outcomes researcher who is evaluating patients after surgical stabilization of the patella; we offer the demographic, physical examination, and radiographic variables we have listed as a foundation on which to build such guidelines.

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Vol. XX, No. X, XXXX

Patellar Instability Factors in MPFL Reconstructions

In addition to evaluating these studies for variables of interest specific to MPFL reconstruction, we also evaluated the overall study quality using the CMS.5 The mean score of 53.5 of a possible 100 points demonstrates that there is a need for improvement in general methodological quality of these studies as well. Most previous studies evaluating methodological quality using the CMS reported lower overall CMS scores than ours.17,34,39 They note, however, that CMS scores were generally lower in older studies and improved over time. Since all of our studies were after 2001, we would expect a slightly higher overall quality of studies. This is consistent with a more recent methodological analysis using CMS in rotator cuff repair studies, which reported higher CMS scores.30 In addition, we also preselected our studies to include only studies with higher quality based on our inclusion and exclusion criteria. Limitations of our study include the possibility that our results are biased based on our inclusion/exclusion criteria; excluded studies may alter the results we found. An additional limitation in this analysis is that the published data span greater than 3 decades of clinical medicine in a field that has seen a surge of new knowledge.

CONCLUSION Current literature on MPFL reconstruction contains diverse methods of recording pre- and postoperative variables. Most studies report on a homogeneous population, with inconsistent applicability to the broad spectrum of patients with patellar instability. The outcomes reporting in our current literature needs more clarity and consistency in reporting methodology to be of value for the treating clinician.

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Patellar instability factors in isolated medial patellofemoral ligament reconstructions--what does the literature tell us? A systematic review.

Many studies have demonstrated good results after medial patellofemoral ligament (MPFL) reconstruction for patients with patellar instability. The app...
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