Biomechanical and Functional Outcomes After Medial Patellofemoral Ligament Reconstruction: A Pilot Study

Is kinesiophobia associated with functional outcome measures in patients following medial patellofemoral ligament reconstruction?

BACKGROUND

This study aimed to investigate the potential relationship between kinesiophobia and functional outcomes in patients following medial patellofemoral ligament reconstruction (MPFLr).

METHODS

Twenty-one patients (six males, 15 females) who underwent MPFLr between 2016 and 2020, (23.57 ± 9.49 years old) with a mean follow up period of 52.33 ± 24.82 months were included in the study. Following an assessment of patellar stability and alignment, kinesiophobia levels, function and balance were measured. The kinesiophobia was measured using the Tampa Scale of Kinesiophobia, while functional outcomes were assessed with the single-leg hop test, Y-Balance test and single-leg sway index. The self-reported function was measured by Kujala patellofemoral score and Lysholm knee score.

RESULTS

The patients exhibited kinesiophobia scores of 43.10 ± 6.90. A negative correlation existed between kinesiophobia and both the Kujala scores (r = -0.75, P < 0.001) and the Lysholm scores (r = -0.79, P < 0.001). Moderate negative correlations were observed between kinesiophobia and the single-leg hop distance (r = -0.64, P < 0.01), as well as in Y-Balance test anterior reach distance (r = -0.51, P < 0.01) and posterolateral reach distance (r = -0.55, P < 0.01). Additionally, a low negative correlation was noted between kinesiophobia and Y-Balance test posteromedial reach distances (r = -0.43, P = 0.05), as well as the total sway index (r = -0.46, P = 0.04).

CONCLUSIONS

A high level of kinesiophobia was strongly correlated with self-reported functional scores and moderately correlated with measured functional outcomes. The findings underscore a notable prevalence of kinesiophobia following biomechanically successful MPFLr. Investigating the impact of kinesiophobia on outcomes after MPFLr may provide a better understanding of patient recovery.

Adolescents with prior patellar dislocation report affected quality of life and function, as measured using the Banff Patella Instability Instrument, Kujala and EQ-5D-5L index scores

PURPOSE

We aimed to establish patient-reported outcome measure (PROM) reference data for a cohort of patients with prior patellar dislocation without previous knee surgery.

METHODS

All inhabitants of the Faroe Islands aged 15-19 years were sent an online survey via secure email to establish a national cohort. They were asked to answer questions regarding demographics, whether they had prior patellar dislocation and to complete the PROMs: the Banff Patella Instability Instrument (BPII), Kujala, Marx activity and EQ-5D-5L questionnaires. Participants who had undergone knee surgery were excluded. Participants who had prior patellar dislocation underwent radiographic examinations to diagnose trochlear dysplasia. The study included three cohorts: the general population, prior patellar dislocation and prior patellar dislocation and trochlear dysplasia cohorts.

RESULTS

Of the 3749 individuals contacted, 1119 completed the survey and responded to at least one PROM. Of these, 102 reported a history of patellar dislocation and 57 of them had trochlear dysplasia. All PROMs, except the Marx score, reflected a worse quality of life and function after patellar dislocation than in the general population cohort; this was most pronounced in the BPII. The percentage of people experiencing problems in EQ-5D-5L dimensions was higher in the patellar dislocation and trochlear dysplasia cohorts than in the general population cohort in all EQ-5D-5L domains, except anxiety/depression.

CONCLUSION

Adolescents who had patellar dislocation reported reduced quality of life and function according to the BPII, Kujala and EQ-5D-5L index values, as well as all EQ-5D-5L domains, except for anxiety/depression. However, their activity levels remained high.

LEVEL OF EVIDENCE

Level III.

Knee Confidence, Fear of Movement, and Psychological Readiness for Sport in Individuals With Knee Conditions: A Systematic Review and Meta-analysis

OBJECTIVES: To (1) compare activity-related psychological factors between individuals with and without knee conditions, and (2) assess associations between these factors and objective measures of function in individuals with knee conditions. DESIGN: A priori registered systematic review with meta-analysis. LITERATURE SEARCH: MEDLINE-Ovid, Embase-Ovid, Scopus-Elsevier, CINAHL-EBSCO, SPORTDiscus-EBSCO, and Cochrane Library were searched to May 27, 2022. STUDY SELECTION CRITERIA: We included peer-reviewed primary data studies (observational and experimental) of human participants with and without knee conditions reporting knee confidence, fear of movement/avoidance beliefs, and/or psychological readiness to return to sport (RTS) or reporting correlations between these factors and objective measures of function in knee conditions. DATA SYNTHESIS: Where possible, data were pooled by knee conditions, otherwise performed narrative syntheses. The Downs and Black checklist assessed the methodological quality of the included studies. RESULTS: Forty studies (3546 participants with knee conditions; 616 participants without knee conditions) were included. There was very low-certainty evidence of higher fear of movement in individuals with knee osteoarthritis (standardized mean difference [SMD], 0.46; 95% confidence interval [CI]: 0.41, 0.52), but not in individuals with patellofemoral pain (SMD, 0.66; 95% CI: -7.98, 9.29) when compared with those without knee conditions. There was very low-certainty evidence of no differences in psychological readiness to RTS after anterior cruciate ligament reconstruction (SMD, -1.14; 95% CI: -2.97, 0.70) compared to no knee condition, and negligible to weak positive correlations between psychological readiness to RTS and objective measures of function. CONCLUSION: There was very low-certainty evidence of higher fear of movement in individuals with knee osteoarthritis compared to those without, and very low-certainty evidence of no correlations between these factors and objective measures of function following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther 2024;54(4):1-14. Epub 29 January 2024. doi:10.2519/jospt.2024.12070.

Association between single leg hop tests and patient reported outcome measures and patellar instability in patients with recurrent patellar dislocations

Objectives

To assess the associations between the single leg hop tests at two premises; baseline and the change after 12 months, and change in patient reported outcome measures and persistent instability after 12 months in patients with recurrent lateral patellar dislocation (RLPD).

Methods

61 RLPD patients aged 12-30 with a mean (±SD) of 19.2 (±5.3) were assessed at baseline, and at 12 months after treatment with either active rehabilitation alone, or medial patellofemoral ligament reconstruction and active rehabilitation. Single leg hop for distance, triple hop for distance, crossover hop for distance and 6-metre timed hop were performed for both legs, and the Limb Symmetry Index (LSI) was calculated. Persistent patellar instability was self-reported as 'Yes' or 'No' at 12-month follow-up. Knee function in sport and recreational activities and knee-related quality of life were assessed at baseline and 12 months follow-up using the Knee injury and Osteoarthritis Outcome Score (KOOS).

Results

LSI for the baseline single leg hop for distance and the triple hop for distance was significantly associated with persistent patellar instability at 12 months follow-up with an OR of 0.94 (95% CI 0.88 to 0.99) and OR of 0.91 (95% CI 0.84 to 0.99), respectively. No other statistically significant associations were detected.

Conclusion

Individuals with higher LSI values for the single leg hop for distance and triple hop for distance conducted at baseline had lower odds for persistent patellar instability at 12 months follow-up. Clinicians can use results from these hop tests to assess the risk of future recurrent patellar instability prior to treatment.

Study design

Retrospective cohort study.

Trial registration number

NCT02263807.

Monitoring lower limb biomechanical asymmetry and psychological measures in athletic populations-A scoping review

BACKGROUND

Lower limb biomechanics, including asymmetry, are frequently monitored to determine sport performance level and injury risk. However, contributing factors extend beyond biomechanical and asymmetry measures to include psychological, sociological, and environmental factors. Unfortunately, inadequate research has been conducted using holistic biopsychosocial models to characterize sport performance and injury risk. Therefore, this scoping review summarized the research landscape of studies concurrently assessing measures of lower limb biomechanics, asymmetry, and introspective psychological state (e.g., pain, fatigue, perceived exertion, stress, etc.) in healthy, competitive athletes.

METHODS

A systematic search of MEDLINE, Embase, CINAHL, SPORTDiscus, and Web of Science Core Collections was designed and conducted in accordance with PRISMA guidelines. Fifty-one articles were included in this review.

RESULTS

Significant relationships between biomechanics (k = 22 studies) or asymmetry (k = 20 studies) and introspective state were found. Increased self-reported pain was associated with decreased range of motion, strength, and increased lower limb asymmetry. Higher ratings of perceived exertion were related to increased lower limb asymmetry, self-reported muscle soreness, and worse jump performance. Few studies (k = 4) monitored athletes longitudinally throughout one or more competitive season(s).

CONCLUSION

This review highlights the need for concurrent analysis of introspective, psychological state, and biomechanical asymmetry measures along with longitudinal research to understand the contributing factors to sport performance and injury risk from biopsychosocial modeling. In doing so, this framework of biopsychosocial preventive and prognostic patient-centered practices may provide an actionable means of optimizing health, well-being, and sport performance in competitive athletes.

Isolated medial patellofemoral ligament reconstruction improves static bipedal balance control in young patients with recurrent lateral patellar instability

BACKGROUND

Knee stability can be safely and reliably restored using medial patellofemoral ligament (MPFL) reconstruction, which is widely recognized in patients with recurrent lateral patellar instability. However, the literature regarding its influence on static balance control is limited. Thus, this study aimed to assess the impact of MPFL reconstruction on balance control and determine its functional significance.

METHODS

The study comprised 26 patients with recurrent lateral patellar instability, scheduled for MPFL reconstruction, and 26 matched healthy controls who underwent double-leg stance static posturographic tests pre- and postoperatively on a vertical force platform. Four test conditions were performed with their eyes open and closed, without and with foam support to evaluate the balance control of all participants. The International Knee Documentation Committee subjective knee form, Lysholm knee scoring scale, Tampa scale for kinesiophobia, and active range of motion of the affected knee were synchronously obtained and assessed.

RESULTS

More postural sway was observed in patients compared to the healthy controls, 11 ± 5 days preoperatively (p < 0.01). However, 374 ± 23 days postoperatively, postural sway between the patients and control subjects was comparable (p > 0.05). Patients following MPFL reconstruction demonstrated better postural stability (p < 0.01). Significant ameliorations were found in all clinical assessments in the study patients postoperatively (p < 0.01).

CONCLUSIONS

Patients with recurrent lateral patellar instability have inefficient balance control. Static bipedal balance control can be improved under surface perturbation in these patients one year after isolated MPFL reconstruction that enhances the possibility of normal restoration of postural stability. Structural recovery of the ligament could help restore the sensorimotor efficiency and generate the compensatory and anticipatory balance regulation strategies, thereby improving joint function.

Feasibility of return to sports assessment 6 months after patellar instability surgery

BACKGROUND

The evidence regarding the usefulness of assessment tools to support decisions of return-to-sport after surgery for patellar instability is scarce. The purpose of this study was therefore to explore the feasibility of functional tests assessing readiness for return-to-sport six months after patellar stabilizing surgery. However, there is little evidence on what a functional assessment should include to support these decisions following surgery for patellar instability. Therefore the purpose of this study was to explore the feasibility of functional tests assessing readiness for return-to-sport six months after patellar stabilizing surgery.

METHODS

In this cross-sectional study a prospective cohort of 78 patients were subjected to a range of return-to-sport readiness tests at six months after surgery for patellar instability with an "a la carte" approach. Lower Quarter Y-Balance Test (YBT-LQ), single-legged hop tests and isokinetic strength tests were performed. In addition, self-reported function was measured with the Banff Patellofemoral Instability Instrument 2.0 (BPII) and Norwich Patellar Instability score (NPI). Return-to-sport clearance criteria were defined as: ≤4 cm YBT-LQ anterior reach difference between legs, leg-symmetry-index (LSI) ≥ 95% in the YBT-LQ composite score, mean sum score LSI ≥ 85% of all single-leg hop tests and LSI ≥ 90% in isokinetic quadriceps strength.

RESULTS

Sixty-four patients (82%) were able to complete all functional tests, while only eleven (14%) patients were deemed ready for return-to-sport, passing all return-to-sport clearance criteria. Patients with bilateral problems demonstrated worse performance in the contralateral leg, which resulted in higher LSI scores compared to individuals with unilateral instability. A supplementary finding was that the extent of surgery (MPFL-R only versus combined surgery) did not predict and mainly did not affect self-reported function or functional performance at the follow-up.

CONCLUSION

The functional assessment used in the current study seems feasible to conduct at six months after patellar stabilizing surgery. However, current suggested clearance standards and the use of leg-symmetry-index seems inappropriate for patients with patellar instability. Therefore, further exploration of appropriate tests and return-to-sport clearance criteria is justified.

TRIAL REGISTRATION

clinicaltrial.gov, NCT05119088. Registered 12.11.2021 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05119088 .

Patients' experiences of living with patellar instability before and after surgery: a qualitative interview study

OBJECTIVES

To explore the experience of living with patellar instability before and after surgery.

DESIGN

Qualitative individual semistructured interviews of patients with patellar instability using a four-step thematic cross-case analysis strategy (systematic text condensation).

SETTING

Two orthopaedic units within two large Hospitals in Norway.

PARTICIPANTS

A convenience sample of 15 participants, aged between 16 and 32 years, who had undergone surgery for patellar instability within the last 6-12 months.

RESULTS

Participants offered rich and detailed descriptions of the impact and lived experience of patellar instability, including fear of new dislocations, increased awareness of the knee and adaptations to avoidance behaviour in everyday life both before and after surgery. The four major themes that emerged from the data were: (1) fear of patella dislocations governs everyday life activities, (2) adaptation to avoidance behaviour, (3) feeling different, misunderstood and stigmatised affects self-esteem and (4) feeling stronger, but still not fully confident in the knee after surgery.

CONCLUSIONS

These findings offer insight into the experience of living with patellar instability. Patients reported that the instability had major impacts on their everyday life, affecting ability to participate in social life and physical activities both before and after surgery. This may imply that an increased attention towards cognitive interventions may be useful in the management of patellar instability.

TRIAL REGISTRATION NUMBER

NCT05119088.

Cross-cultural Validation of the Norwegian Version of the Banff Patellofemoral Instability Instrument 2.0

Background

The Banff Patellofemoral Instability Instrument (BPII) 2.0 is a disease-specific quality of life questionnaire for patients with patellofemoral instability. While good psychometric properties have been demonstrated, the data lack cross-cultural validity, construct validity, and an established measurement error.

Purpose

To (1) translate and cross-culturally adapt the BPII 2.0 to the Norwegian version (BPII 2.0-No) and (2) examine the psychometric properties of the Norwegian version.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

The BPII 2.0 was translated according to international guidelines. A cohort of 100 patients surgically treated for recurrent patellofemoral instability completed the BPII 2.0-No, related outcome measures (Norwich Patellar Instability Score, International Knee Documentation Committee Subjective Knee Form 2000, Knee injury and Osteoarthritis Outcome Score, and Tampa Scale of Kinesiophobia), and functional tests (Y-Balance Test-Lower Quarter, single-leg hop tests, and knee extension strength) before and/or 6 months after surgery. We evaluated the face and content validity, internal consistency (Cronbach α), test-retest reliability (intraclass correlation coefficient [ICC]), measurement error (SEM and smallest detectable change at the individual [SDCind] and group levels [SDCgroup]). Construct validity was assessed by testing 9 hypotheses on the correlation between the BPII 2.0-No and the outcome measures/functional tests (Pearson r).

Results

The BPII 2.0-No had good face and content validity. Internal consistency was excellent (α = .95), and no floor or ceiling effects were found. Test-retest reliability was high (ICC2,1 = 0.87; 95% CI, 0.77-0.93), and measurement error was low (SEM = 7.1). The SDCind was 19.7 points and the SDCgroup was 2.8 points. Eight of the 9 hypotheses regarding construct validity were confirmed.

Conclusion

The BPII 2.0-No was found to be valid and reliable. This study adds further knowledge on the measurement properties of the BPII 2.0 that can be used internationally.

Preoperative Patella Alta on Caton-Deschamps Index Is a Predictor of Outcome Following Isolated Medial Patellofemoral Ligament Reconstruction

Purpose

The purpose of this study was to determine whether a preoperative Caton-Deschamps index (CDI) ≥ 1.30, as measured by magnetic resonance imaging, is associated with rates of postoperative instability, revision knee surgery, and patient-reported outcomes in patients undergoing isolated medial patellofemoral ligament (MPFL) reconstruction.

Methods

Patients who underwent primary medial patellofemoral ligament reconstruction (MPFLR) between 2015 and 2019 at a single institution were assessed. Only those with at least 2 year follow up were included. Patients who had undergone a previous ipsilateral knee surgery, concomitant tibial tubercle osteotomy and/or ligamentous repair/reconstruction at the time of MPFL reconstruction were excluded from the study. CDIs were evaluated by three investigators based on magnetic resonance imaging measurement. Patients with a CDI ≥ 1.30 were included in the patella alta group, while those with a CDI between 0.70 and 1.29 served as controls. A retrospective review of clinical notes was used to evaluate the number of postoperative instability episodes and revisions. Functional outcomes were measured by the International Knee Documentation Committee (IKDC) and 12-Item Short Form Health Survey (SF-12) physical and mental scores.

Results

Overall, 49 patients (50 knees, 29 males, 59.2%) underwent isolated MPFLR. Nineteen (38.8%) patients had a CDI ≥ 1.30 (mean: 1.41, range: 1.30-1.66). The patella alta group was significantly more likely to experience a postoperative instability episode (36.8% vs 10.0%; P = .023) and was more likely to return to the operating room for any reason (26.3% vs 3.0%; P = .022) compared to those with normal patellar height. Despite this, the patella alta group had significantly greater postoperative IKDC (86.5 vs 72.4; P = .035) and SF-12 physical (54.2 vs 46.5; P = .006) scores. Pearson's correlation showed a significant association between CDI and postoperative IKDC (R ² = 0.157; P = .022) and SF-12P (R ² = .246; P = .002) scores. There was no difference in postoperative Lysholm (87.9 vs 85.1; P = .531). and SF-12M (48.9 vs 52.5; P = .425) scores between the groups.

Conclusion

Patients with preoperative patella alta, as measured by CDI had higher rates of postoperative instability and return to the OR with isolated MPFL reconstruction for patellar instability. Despite this, higher preoperative CDI was associated with greater postoperative IKDC scores and SF-12 physical scores in these patients.

Level of Evidence

Retrospective cohort study, Level IV.

Return to Sport After Medial Patellofemoral Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

Patellar instability is frequently encountered in the athletic population. Medial patellofemoral ligament (MPFL) reconstruction is a common strategy to treat recurrent patellar dislocation and demonstrates good clinical outcomes.

PURPOSE/HYPOTHESIS

The purpose was to examine return to sport after MPFL reconstruction for patellar instability. We hypothesized that patients would resume athletic activity at a high rate and that a large proportion would return to their preoperative level of performance.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of the literature was conducted using PubMed and Cochrane Library databases to identify articles reporting return to sport after MPFL reconstruction for recurrent patellar dislocation. Athletes were defined as those reporting a preoperative sport. A random-effects model was used to evaluate return to sport rates, subsequent level, and rate of instability recurrence. Meta-regression was used to compare return to sport rates in patients undergoing MPFL reconstruction without osteotomy compared with those treated with simultaneous tibial tubercle osteotomy or trochleoplasty.

RESULTS

In total, 23 articles met inclusion criteria after full-text review. A total of 930 patients were analyzed, including 786 athletes. Women represented 61.3% of all patients. The overall mean age was 21.1 years (range, 9.5-60.0 years), with a mean follow-up time of 3.0 years (range, 0.8-8.5 years). The return to sport rate was 92.8% (95% CI, 86.4-97.6). Patients returned to or surpassed their preoperative level of activity in 71.3% (95% CI, 63.7-78.4) of cases. An osteotomy was performed on 10.5% of athletes. Return to sport did not differ significantly in patients undergoing MPFL reconstruction without osteotomy versus those receiving additional osteotomy (95.4% vs 86.9%; P = .22). Patients returned to sport at a mean of 6.7 months (range, 3.0-6.4 months) postoperatively. Osteotomy did not affect return time. Complications occurred at an overall rate of 8.8%. The most common complication was recurrence of instability (1.9%; 95% CI, 0.4-4.0). The Kujala score was reported by 13 studies, with pre- and postoperative combined means of 60.3 and 90.0, respectively.

CONCLUSION

MPFL reconstruction is an effective and reliable treatment in the setting of patellofemoral instability. Surgeons can counsel their patients that they can expect a high rate of return to sport after MPFL reconstruction surgery alone or with concomitant osteotomy.

Objectively quantified lower limb strength recovery in people treated surgically or non-surgically after patellar dislocation: A systematic review

OBJECTIVE

Synthesize evidence on objectively quantified lower limb strength recovery in people treated surgically or non-surgically after patellar dislocation.

METHODS

MEDLINE, EMBASE, Cochrane Library, SPORTDiscus, PEDro, AMED and CINAHL databases were last searched on July 30th, 2020 for randomized controlled trials and observational studies that objectively quantified lower limb strength in people (any age or sex) treated surgically or non-surgically after patellar dislocation.

RESULTS

24 studies were included (877 participants, median age 20.7). All assessed knee extension strength, 11 knee flexion strength, three hip abduction strength, two hip external rotation strength, and one hip flexion, extension, adduction, and internal rotation strength. One randomized controlled trial judged at high risk of bias and two cohort studies with methodological limitations compared lower limb strength recovery between surgically and non-surgically treated people, with conflicting findings. After surgery, median long-term (>8 months) knee extension strength was 82.5% (IQR 78.5-88.2; 13 studies) of the unaffected leg and knee flexion strength was 91.5% (IQR 90.7-96.9; five studies). After non-surgical treatment, median long-term knee extension strength was 86% (IQR 79.3-87.4; four studies) and mean flexion strength ranged from 95.2 to 96.7% (two studies). Mean hip strength was always >90% (two studies). Two redislocations during eccentric isokinetic knee testing and knee pain during isokinetic knee extension testing were reported as adverse events.

CONCLUSIONS

Available evidence indicates that after patellar dislocation, knee extension strength deficits in the affected limb are frequently observed and can persist long term, but this remains uncertain due to the limitations of relevant included studies. Whether lower limb strength recovery differs between people treated surgically and those treated non-surgically after patellar dislocation also remains uncertain.

TRIAL REGISTRATION

(PROSPERO CRD42019139533).

Arthroscopic assessment of patella tracking correlates with recurrent patellar instability

PURPOSE

For recurrent lateral patellar instability surgical algorithm, an arthroscopic assessment of patellar tracking can aid with the decision of adding a tibial tubercle transfer procedure based on knee flexion angle at which patella centrally engages in its groove. Tibial tubercle-trochlear groove distance is variable in normal values and has discrepancies between imaging modalities. The aims of our study were to assess correlation of arthroscopic patellar tracking technique with recurrent patellar instability, and to assess the accuracy and reproducibility of this technique.

METHODS

157 patients were evaluated, 64 control patients with no patellar instability, and 93 patients with recurrent patellar instability. This included 57 consecutive knee arthroscopy procedures evaluated for accuracy and reproducibility of our technique. The technique involved low flow arthroscopy and anterolateral viewing portal. Patients' knees were extended from a flexed position of 120°, and paused when the patella disengaged from its groove. The KFA was then estimated by the primary surgeon, and compared with a goniometer measurement. The assisting surgeon, blinded to the primary surgeon measurements, repeated this process. For the primary outcome, goniometer readings for KFA from the primary surgeon were used to correlate with patellar instability diagnosis.

RESULTS

Patients with patellar instability had a mean KFA of 118° compared to 44°for patients without patellar instability (p < 0.001). The mean difference between goniometer reading and estimation of KFA by each surgeon was 5° (p < 0.001) with intra-class correlation of 0.99. The mean difference between the two surgeons' goniometer readings was 8° (p < 0.001) with intra-class correlation of 0.99.

CONCLUSION

This study confirms arthroscopic assessment of patella tracking is accurate, reproducible, and a knee flexion angle of greater than 44° correlates with patellar instability diagnosis. Patella tracking can be used as an adjunct or an alternative assessment method to tibial tubercle-trochlear groove distance to determine the need for tibial tubercle transfer in patellar stabilisation surgery.

LEVEL OF EVIDENCE

Prospective Cohort Study, Level III.

Good Outcomes of Combined Femoral Derotation Osteotomy and Medial Retinaculum Plasty in Patients with Recurrent Patellar Dislocation

Objectives

To report the clinical outcomes of combined femoral derotation osteotomy and medial retinaculum plasty for recurrent patellar dislocation in patients with excessive femoral anteversion.

Methods

From January 2015 to March 2018, 20 knees in 20 patients (18 female, 2 male) with a mean age of 21 ± 4.2 years (range, 16 to 28 years) were retrospectively reviewed. All patients had undergone femoral derotation osteotomy and medial retinaculum plasty for recurrent patellar dislocation and excessive femoral anteversion angle (FAA > 25°). CT and X‐rays were used to assess the correction of the femoral anteversion angle, the tibia tuberosity‐trochlear groove (TT‐TG) distance, patellar tilt, and the congruence angle following the combinatory operations. Subjective scores, such as Kujala, International Knee Documentation Committee (IKDC), Tegner, and visual analogue scale (VAS) scores, were used to evaluate knee function preoperatively and postoperatively.

Results

No recurrence of patellar dislocation occurred in these patients during an average of 18 months (range, 12 to 23 months) of follow‐up. The mean of the FAA was corrected to 15.80° ± 3.58° postoperatively compared with 31.42° ± 4.95° preoperatively (P < 0.001). The TT‐TG distance was decreased from 22.17 ± 5.28 mm before surgery to 19.42 ± 4.57 mm after surgery (P = 0.03). The patellar tilt and congruence angle were improved from 30.43° ± 5.30°, 43.30° ± 11.04° to 15.80° ± 3.94°, 16.64° ± 9.98°, respectively (P < 0.001). The Kujala score was improved from 72.4 ± 19.90 before the surgery to 88.2 ± 12.25 after the surgery (P < 0.001). The IKDC score was improved from 70.56 ± 21.44 to 90.78 ± 14.32, and the VAS score was decreased from 4.23 ± 2.11 preoperatively to 1.27 ± 1.08 postoperatively (P < 0.001). No significant difference in Tegner score (5.46 ± 2.49 vs 5.79 ± 1.44) was found before and after the surgery (P = 0.2). Patients younger than 20 years old had lower Kujala (83.46 ± 14.56 vs. 90.84 ± 7.74, P = 0.02) and IKDC (83.49 ± 17.35 vs 92.46 ± 9.28, P = 0.04) scores than those older than 20 years.

Conclusion

Good knee function, pain relief, and improved patellofemoral congruence were achieved with the combined femoral derotation osteotomy and medial retinaculum plasty. The combined operations serve as an ideal treatment for recurrent patellar dislocation and address the primary risk factors.