Influence of rupture patterns of the medial patellofemoral ligament (MPFL) on the outcome after operative treatment of traumatic patellar dislocation

Purpose

Patellar dislocation usually occurs to the lateral side, leading to ruptures of the medial patellofemoral ligament (MPFL) in about 90 % of all cases. Reliable prognostic factors for the stability of the patellofemoral joint after MPFL surgery and satisfaction of the patient have not been established as yet.

Methods

This multicentric study retrospectively included 40 patients with a mean age of 22.4 ± 8.1 years (range 9–48) from 5 German Trauma Departments with first-time traumatic patellar dislocation and operative treatment. Surgery was limited to soft tissue repairs, and a preoperative magnetic resonance imaging (MRI) was performed in all cases. Evaluation of the MRI included sulcus angle, dysplasia of the trochlea, depth and facet asymmetry of the trochlea, Insall-Salvati index, Tibial tuberosity to trochlear groove (TTTG) distance, and rupture patterns of the MPFL. Patients were interrogated after 2 years about recurrent dislocation, satisfaction, and the Kujala score.

Results

Trochlea facet asymmetry was significantly lower in patients with redislocation (23.5 ± 18.8) than in patients without redislocation (43.1 ± 16.5, p = 0.03). Patients with a patellar-based rupture were significantly younger (19.5 ± 7.2 years) than patients without patellar-based rupture (25.4 ± 8.1 years, p < 0.02). Patients with femoral-based ruptures were significantly older (25.7 ± 9.2 years) than patients without femoral-based rupture (19.7 ± 6.1 years, p < 0.02), and had a significantly higher TTTG distance (10.2 ± 6.9 vs. 4.5 ± 5.5, p < 0.02). Patients with incomplete ruptures of the MPFL had a significantly lower Insall-Salvati index (1.2 ± 0.2 vs. 1.4 ± 0.2, p = 0.05). The Kujala score in patients with redislocations was significantly lower (81.0 ± 10.5 points) than in patients without redislocation (91.9 ± 9.2 points, p < 0.02).

Conclusion

Younger patients more often sustain patellar-based ruptures following first-time traumatic patella dislocation, while older patients more often sustain femoral-based ruptures of the MPFL. Incomplete MPFL ruptures are correlated with lower Insall-Salvati indices. Low trochlear facet asymmetry is correlated with higher rates of redislocation. These results may be of relevance for the operative and postoperative treatment in the future.

Level of evidence

Prognostic study, Level IV.     

Medial retinacular flap advancement and arthroscopic lateral release for symptomatic chronic patellar lateral subluxation with tilting

Purpose

The purpose of this study was to investigate outcomes of surgical treatment in patients with symptomatic chronic patellar lateral subluxation with tilting.

Methods

Thirty-two patients (38 knees) underwent arthroscopic lateral release and mini-open advancement of medial retinacular flap for the treatment of symptomatic chronic patellar lateral subluxation with tilting with a mean follow-up of 52.0 ± 11.4 months. The mean age at surgery was 24.7 ± 8.8 years, and the duration of symptoms was 4.8 ± 4.1 years. The patellofemoral function of the knee was evaluated before surgery and at the clinical follow-up using the Kujala functional score.

Results

Thirty-six knees (95 %) showed excellent or good results after surgery. Two knees with grade IV chondromalacia of the patella had fair results with persistent apprehension signs and persistent pain. The Kujala patellofemoral functional scores improved by an average of 20.9 points from a mean value of 71.8 ± 12.1 preoperatively to 92.7 ± 10.7 postoperatively (P < 0.01). Radiographically, there were significant improvements in congruence angle from 23.4° ± 7.9° preoperatively to ?7.2° ± 6.4° postoperatively (P < 0.01) and in the lateral patellofemoral angle from ?8.6° ± 6.8° preoperatively to 6.3° ± 4.2° postoperatively (P < 0.01).

Conclusions

Medial retinacular flap advancement and arthroscopic lateral release offer a promising treatment for symptomatic chronic patellar lateral subluxation and tilt without frank traumatic episode.

Level of evidence

Retrospective study, Level IV.     

Anatomical two-bundle medial patellofemoral ligament reconstruction with hardware-free patellar graft fixation: technical note and preliminary results

Purpose

Various techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been developed. In this article, a modified technique for anatomical two-bundle MPFL reconstruction with hardware-free patellar graft fixation is described and the preliminary results of this technique are presented.

Methods

A modified surgical technique for MPFL reconstruction with a gracilis tendon autograft and hardware-free patellar graft fixation using two short oblique bone tunnels is described in detail. Complications and preliminary results of this procedure were assessed in 19 patients at a mean follow-up of 16 ± 3 months using the Kujala score, Tegner scale, and Insall score.

Results

No postoperative patellar dislocation or subluxation was reported. Eighty-nine per cent of the patients were either satisfied or very satisfied with the overall outcome. The mean Kujala score was 92 ± 7 (range 69–100), and the median Tegner scale was 5 (range 3–7). According to the Insall score, the results of 18 patients (95 %) were rated as good or excellent. Postoperative complications occurred in 3 patients (16 %), with two of them persisting only temporary.

Conclusions

The described technique for anatomical two-bundle MPFL reconstruction is a safe and effective surgical procedure for the treatment of lateral patellar instability, with several methodical advantages compared to similar techniques. Further evaluation in a larger patient cohort with a longer follow-up is necessary to confirm these short-term results.

Level of evidence

IV.     

The horizontal Y-shaped graft with respective graft tension angles in anatomical two-bundle medial patellofemoral ligament reconstruction

Purpose

Various techniques for medial patellofemoral ligament (MPFL) reconstruction have been described with two bundles of graft tensioned simultaneously. The present study was to introduce an anatomical reconstruction procedure using a horizontal Y-shaped graft with respective graft tension angles and report the preliminary results.

Methods

A surgical technique for MPFL reconstruction using a horizontal Y-shaped semitendinosus tendon autograft with two bundles tensioned at 0° and 30° of knee flexion was described in detail. The patellar stability was evaluated with the apprehension test and an axial computed tomography (CT) scan at 30° of knee flexion. The knee function was evaluated using the Lysholm and Kujala scores.

Results

No recurrent dislocation or subluxation was reported for 45 patients at a mean of 33.7-month follow-up. On CT images, congruence angle, patellar tilt angle, lateral patellar angle and lateral displacement were restored to the normal range. At the last follow-up, the mean Lysholm score improved from 51.8 ± 6.2 to 91.7 ± 4.1 and mean Kujala score was from 53.4 ± 5.3 to 90.9 ± 6.6 (P < 0.01).

Conclusions

The present anatomical MPFL reconstruction technique with a horizontal Y-shaped two-bundle graft tensioned at respective knee flexion angles could not only recreate the fan-shape of MPFL but also mimic the function bundles of native ligament. Clinical follow-up confirms the good restoration of the patellar stability and significant improvement of knee function without special complications.

Level of evidence

Therapeutic, Level IV.

     

Medial patellofemoral ligament reconstruction with bioactive synthetic ligament is an option. A 3-year follow-up study

Purpose

The purpose of this study was to evaluate mid-term follow-up results of medial patellofemoral ligament (MPFL) reconstruction using a bioactive synthetic ligament in the treatment of objective patellofemoral (PF) instability.

Methods

Sixteen patients (18 knees) presenting with objective PF instability underwent a MPFL reconstruction, isolated or associated with other surgical procedures for PF stabilization. All patients were clinically evaluated at a minimum follow-up of 3 years. Kujala, subjective IKDC and KOOS scores were used to assess clinical outcome. Pre-operative and post-operative pain was quantified with VAS scale and the overall satisfaction graded according to Insall and Crosby. Although none of the patients in this series were involved in high-level sports activity because of patellofemoral instability, activity level pre-operatively and at follow-up were evaluated according to Tegner scale.

Results

No recurrence of dislocation was observed in this series. The overall satisfaction rate was 88.8 %. Kujala score improved significantly from 57 ± 8.4 to 84.3 ± 10.2 points (p < .01). Both subjective IKDC (42.4 ± 7.13 to 70.1 ± 3.9) and KOOS (62.7 ± 4.34 to 82.8 ± 8.8) significantly improved from pre-operative evaluation (p < .01). VAS decreased from a mean pre-operative value of 2.5 ± 1.6 to 1.4 ± 1.5 at 3 years follow-up. Only one patient required revision debridement surgery for persistent medial epicondylar pain.

Conclusions

Isolated or associated MPFL reconstruction with bioactive synthetic ligament is a valid option in surgical treatment of objective PF instability, with results at mid-term follow-up comparable to autologous graft, thus minimizing donor-site morbidity and associated complications.

Level of evidence

IV.     

Non-surgical treatment for acute patellar dislocation with special emphasis on the MPFL injury patterns

Purpose

The objective of present study was to propose a new classification for acute MPFL injury, which can help choose optimal treatment method for certain injury type.

Methods

Eighty-five patients with acute patellar dislocation treated non-surgically were retrospectively reviewed. They were assigned into two groups according to the newly introduced classification scheme, which classified MPFL injury into three types: injury in overlap region, injury in non-overlap region and combined injury of both regions. For study purpose, patients with combined injury were not included. Of 85 patients, 33 were in the overlap-region group (Group 1) and 52 in the non-overlap-region group (Group 2). Clinical patellar instability rate and patellofemoral score were measured and recorded at 2-year follow-up.

Results

The patellar instability rate was 15.2 % in Group 1 and 38.5 % in Group 2, with statistically significant difference between the two groups (P = 0.022). The mean visual analogue scale for Group 1 and Group 2 was 15.6 points and 28.3 points, respectively (P = 0.026). The mean Kujala score was 91.1 points and 82.6 points (P = 0.009), with a good or excellent subjective result recorded for 27 of 33 patients (81.8 %) in Group 1 compared with 30 of 52 patients (57.7 %) in Group 2 (P = 0.021).

Conclusions

Non-surgical treatment achieves better clinical outcomes with respect to a lower patellar instability rate and better subjective function for the overlap-region injury of MPFL than for the non-overlap-region injury, and can be considered as treatment of choice for overlap-region injury of MPFL. The optimal choice for the non-overlap-region injury still requires further researches.

Level of evidence

Therapeutic, Level IV.     

Comparative analysis of medial patellofemoral ligament length change pattern in patients with patellar dislocation using open-MRI

Purpose

Medial patellofemoral ligament (MPFL) reconstruction has become a common form of treatment for recurrent patellar dislocation. This study was performed using open-MRI to compare the length change pattern of MPFL in patients with a history of patellar dislocation to that in healthy subjects.

Methods

The subjects comprised 10 knees of 8 males and 13 knees of 12 females with a history of one or more patellar dislocations. The length of the MPFL was measured using open-MRI in both the leg-extended position and knee-flexed positions to analyse the length change pattern.

Results

The average MPFL lengths were 58.6 ± 6.5 mm and 52.0 ± 4.6 mm for males and females in the extended knee position, respectively. The length change pattern of the MPFL showed slight variation up to a flexion angle of 30° and a clear decrease above 30°. This pattern differed from that of normal MPFL. In terms of morphology, the fibre bundle of the damaged MPFL followed a convex course towards the side of the patellofemoral joint surface at a knee flexion angle of 60°, whereas that of the normal MPFL followed a straight course.

Conclusion

The in vivo damaged MPFL length change pattern was specific and differed distinctly from that of normal MPFL. The results of the present study suggested that MPFL fibres with a history of patellar dislocation lack sufficient tension at knee flexion angles of 0°–60°. However, further studies are needed to obtain a better understanding of cases with a patellar dislocation or postsurgical cases of MPFL reconstruction.

Level of evidence

III.

     

The influence of medial patellofemoral ligament on patellofemoral joint kinematics and patellar stability

Purpose

Retinacular restraints have a critical role in patellar tracking, limiting the movement of the patella in the trochlear groove. The medial patellofemoral ligament (MPFL) is probably the main stabilizer against lateral displacement; few studies are focused on MPFL role on patellofemoral kinematics and patellar stability. The main goal of this in vitro study was to analyse the influence of the MPFL on the kinematics of the patellofemoral joint and patellar stability.

Methods

Using a non-image-based navigation system, kinematics and anatomical data of six fresh-frozen specimens were collected. A passive flexion–extension from 0° to 90° and static acquisitions at 0°, 30°, 60° and 90°, with and without 25 N of lateral load, were performed with intact and resected MPFL with a 60 N axial force applied to the isolated quadriceps tendon. Patellar tilt and shift were analysed.

Results

The MPFL intact state showed a shift in medial direction during the first degrees of knee flexion—that disappeared in MPFL resected condition—followed by a lateral shift, similar to that of MPFL resected condition. Tilt analysis showed that patella rotated laterally until 85° of knee flexion for intact MPFL condition and until 70° for resected MPFL condition and after rotated medially. Static tests showed that patellar stability was significantly affected by MPFL resected condition in particular at 30° and 60°.

Conclusions

The MPFL has an aponeurotic nature. It works as a restraint during motion, with an active role under high stress on lateral side, but with a small contribution during neutral knee flexion. Its biomechanical behaviour under loading conditions should be kept into account when performing surgical reconstruction of this ligamentous structure.     

Medial capsule reefing in patellar instability

Purpose

The efficacy of medial capsule reefing in the treatment of patellar instability is well documented. Aim of the present study was to prospectively evaluate the outcomes of an all-arthroscopic medial capsule reefing technique in young patients with painful patella syndrome and potential patellar instability.

Methods

Thirty patients with painful patellar syndrome and potential patellar instability having undergone a minimum of 6 months of intensive rehabilitation were enrolled in the present study. All subjects were evaluated with physical examination, clinical and functional outcomes and complete imaging study.

Results

All patients were reviewed at an intermediate follow-up of 72 months. Average Kujala score improved from 72.9 ± 15.0 to 88.4 ± 7.6 (p < 0.0001), average Larsen score from 15.0 ± 2.5 to 17.2 ± 2.2 (p < 0.002), average Lysholm from 63.8 ± 16.7 to 87.9 ± 11.7 (p < 0.0001) and average Fulkerson score from 69.5 ± 21.5 to 90.8 ± 9.8 (p < 0.0001). No intraoperative or postoperative complications were recorded. Ninety per cent of patients were very satisfied or satisfied with their functional result. Twenty-eight patients were reviewed at the final follow-up, 120 months after surgery. Average Kujala was 87.7 ± 8.8 (p < 0.0001), average Larsen was 16.8 ± 2.7 (p < 0.01), average Lysholm was 87.6 ± 14.3 (p < 0.0001), and average Fulkerson was 87.2 ± 13.9 (p < 0.0001). Almost 86 % of patients were very satisfied or satisfied with their result. However, slight deterioration of the outcomes over time was observed.

Conclusion

At the final follow-up, the outcomes of all-arthroscopic technique were significantly improved from preoperative values; however, they were slightly inferior at the 72 months follow-up. This slight deterioration of the outcomes may be the consequence of the reduction in physical activities.

Level of evidence

Case series, Level IV.     

Radiographic landmarks for tunnel placement in reconstruction of the medial patellofemoral ligament

Purpose

To verify the findings of previous studies in confirming radiographic landmarks for the femoral attachment of the medial patellofemoral ligament (MPFL), but also to define radiographic landmarks for the patellar attachment. Assess the effect of limb rotation upon these radiographic landmarks.

Methods

The medial patellofemoral ligament was identified in ten fresh-frozen human cadaveric knees. A headed pin was used to mark the centre of the femoral and patellar attachments. True lateral radiographs were performed followed by lateral radiographs in 10° and 20° of internal and external rotation. Posterior-anterior and proximal?Cdistal position of the headed pin was evaluated.

Results

The femoral attachment averaged 3.8?±?5.0?mm anterior to the posterior femoral cortical line and 0.9?±?2.4?mm distal to the perpendicular line intersecting the posterior aspect of Blumensaat??s line. The patellar attachment averaged 7.4?±?3.5?mm anterior to the posterior patellar cortical line, 5.4?±?2.6?mm distal to the perpendicular line intersecting the proximal margin of the patellar articular surface. There was a significant relationship between limb rotation and distance of femoral and patellar attachment from the posterior cortical line (P?<?0.0001 and P?<?0.0002 respectively).

Conclusion

Radiographic landmarks for the femoral attachment of the MPFL identified in this study are comparable with other recent work. This study describes new radiographic landmarks for the patellar attachment of the MPFL and highlights that it is essential to acquire true lateral radiographs if these radiographic landmarks are to be interpreted accurately.     

Medial patellotibial ligament (MPTL) reconstruction for patellar instability

Purpose

To evaluate mid-term clinical and radiographic outcomes after an original medial patellotibial ligament reconstruction in patients with patellar dislocation.

Methods

Twenty-nine knees (27 patients, 8 males and 19 females) treated for patellar dislocation with medialization of the patellar tendon medial third combined with medial and lateral release were evaluated clinically and radiographically at a mean follow-up of 6.1 ± 2.5 years. Trochleoplasty was performed in case of severe flat trochlea (6 knees, 21 %). Aetiology of patellofemoral instability was traumatic in 6 (21 %) and atraumatic in 23 (79 %) knees. The mean age at first dislocation was 19.2 ± 10.1 years. WOMAC, subjective and objective IKDC, Kujala, VAS for pain, Tegner activity and EQ-5D scores were used. Anteroposterior, lateral and 30° axial views were performed for radiographic monitoring.

Results

There was a significant improvement of all clinical scores and significant reduction in knee pain. Twenty-four knees (83 %) were normal or nearly normal by objective IKDC score at final follow-up. Radiographs showed a higher incidence of patella alta and flat trochlea in the atraumatic group. Severe signs of patellar osteoarthritis were found in 1 knee (3 %). A higher body mass index (BMI) was correlated with worse pre-operative scores. Four knees (14 %) were considered failures (2 further dislocations, 2 revision surgeries). The overall survival rate at 6 years was 0.811.

Conclusions

The presented techniques produced good clinical and radiographic results at mean 6.1 years follow-up, with 14 % failures. Signs of patellofemoral dysplasia were found in patients with atraumatic patellar dislocation. BMI was related to worse pre-operative clinical status.

Level of evidence

Retrospective study, Level IV.     

Dynamic versus static reconstruction of the medial patellofemoral ligament for recurrent lateral patellar dislocation

Purpose

To compare clinical and radiological outcomes of static and dynamic medial patellofemoral ligament (MPFL) reconstruction techniques.

Methods

In a retrospective, matched-paired, cohort analysis, 30 patients surgically treated for recurrent lateral patellar dislocation were divided into two groups of 15 patients matched for inclusion and exclusion criteria. The static technique group underwent rigid fixation of the gracilis tendon at the anatomic femoral MPFL insertion and the superomedial border of the patella; the dynamic technique group underwent detachment of the gracilis tendon at the pes anserinus with fixation to the proximal medial patellar margin via tunnel transfer obliquely through the patella. Kujala, Lysholm, and Tegner scores; pain level; and pre- and postoperative radiographic changes of patellar height, patellar tilt, and bisect offset were compared.

Results

No significant between-group differences were found in mean Kujala, Tegner, Lysholm, or visual analogue scale scores or radiographic parameters. One case of resubluxation was observed in the dynamic group. All but one patient in each group would have been willing to undergo the procedure again.

Conclusions

Both techniques provided satisfactory short-term outcomes.

Level of evidence

III.     

The influence of risk factors on clinical outcomes following anatomical medial patellofemoral ligament (MPFL) reconstruction using the gracilis tendon

Purpose

Patellofemoral instability is influenced by ligamentous, boney and neuromuscular factors. The most important variables are trochlea geometry, medial patellofemoral ligament (MPFL), patella height, tibial tuberosity–trochlea groove distance (TT–TG) and the extensor muscles. Treatment is complicated by these multifactorial conditions. This prospective study examined the influence of risk factors on clinical results and athletic activities where treatment was confined to ligamentous procedures only.

Methods

Fifty patients with chronic patellofemoral instability were treated with MPFL reconstruction using an autologous gracilis tendon. Clinical data, radiographs and magnetic resonance imaging (MRI) were prospectively evaluated pre- and postoperative (minimum follow-up 12 month) to detect existing risk factors for patellofemoral instability and to evaluate clinical and sport ability scores (Kujala, Valderrabano).

Results

There was a low rate of redislocation (2 %) and an average Kujala score of 87 ± 13 points postoperative. The MRI showed good integration of the reconstructed MPFL and a positive effect regarding the decrease of patella tilt (16.1° to 11.2°). A negative relationship was found between the degree of trochlear dysplasia and outcomes. 80 % of all patients returned to the same or higher level of physical activity.

Conclusions

Addressing only ligamentous factors through MPFL reconstruction leads to satisfying clinical results and low redislocation rates in most patients. In cases with a high degree of trochlear dysplasia and enlarged TT–TG, additional procedures such as trochleaplasty and tibial tuberosity transfer should be considered as well.

Level of evidence

IV.     

Lateral retinaculum plasty instead of lateral retinacular release with concomitant medial patellofemoral ligament reconstruction can achieve better results for patellar dislocation

Purpose

To elucidate the outcomes of lateral retinaculum plasty versus lateral retinacular release with concomitant medial patellofemoral ligament (MPFL) reconstruction.

Methods

In a prospective study, 59 patients treated at our institution from 2012 to 2014 were included. The 59 patients were randomly divided into two groups. Group I included 27 patients who underwent lateral retinacular release and MPFL reconstruction. Group II included 32 patients who underwent lateral retinaculum plasty and MPFL reconstruction. All patients were followed up for at least 2 years and all assessments were performed both pre- and post-operation. Clinical evaluation consisted of the Kujala score, patellar medial glide test, and patellar tilt angle, patellar lateral shift, and congruence angle, measured on CT scan.

Results

Significant improvement was seen after surgery in both groups. The group of lateral retinaculum plasty achieved better results than the group of lateral retinacular release. No statistically significant differences were found in lateral patellar shift (ns) or congruence angle (ns) between the groups. There were significant differences in Kujala score (P?<?0.05) patellar tilt angle (P?<?0.05), and patellar medial glide test (P?<?0.05) between the groups.

Conclusions

MPFL reconstruction with lateral retinaculum plasty yielded better results than MPFL with lateral retinacular release. Postoperatively, medial and lateral function were restored, and patellar tracking was normal. Lateral retinaculum plasty is a new method that reduces the complications of lateral retinacular release for patellar dislocation.

Level of evidence

II.

     

Patellar tracking should be taken into account when measuring radiographic parameters for recurrent patellar instability

Purpose

To date, many radiographic parameters on patellar instability have their measurements taken statically, and have not been studied in various degrees of flexion according to the patellar tracking. There are also limited data regarding the use of these parameters in predicting recurrent patellar dislocation. The current study aims to review the radiographic parameters of the patellofemoral joint in different degrees of knee flexion and to correlate them with the presence of recurrent instability.

Methods

A 10-year retrospective study was conducted on all patients who had computed tomography patellar-tracking scan done for patellar instability when aged 18 years or younger. The computed tomography patellar-tracking scans were performed with the knee in extension, 10° flexion, and 20° flexion. The axial radiographic parameters were evaluated at the patellar equator, roman arch, and distal patellar pole. Sagittal and coronal parameters were noted. Radiographic parameters were then correlated with recurrent patellar instability.

Results

The femoral sulcus angle and trochlear groove depth at the distal patellar pole in 10° knee flexion (p value 0.04 and 0.03, respectively) and patellar equator in 20° knee flexion (p value 0.02 and 0.03, respectively) had the most significant clinical correlations with recurrent instability on multivariate analysis. Other radiographic parameters found to have significant clinical correlation on univariate analysis include the patellar tilt angle, congruence angle, femoral sulcus angle, trochlear groove depth, and Wiberg’s classification.

Conclusions

As per the knee dynamics, axial radiographic parameters had the most significant correlation with recurrent patellar instability when measured at the distal patellar pole in 10° knee flexion and at the patellar equator in 20° knee flexion. Future axial radiographic evaluation of patellofemoral instability should then be performed at these degrees of knee flexion and axial cuts. Trochlear dysplasia, as measured by the femoral sulcus angle and trochlear groove depth, was the most significant predictor of recurrent patellar instability in the skeletally immature. Wiberg’s classification was also a novel factor found to have clinical correlation with patellofemoral instability.

Level of evidence

III.

     

Treatment of isolated patellofemoral osteoarthritis with lateral facetectomy plus Insall’s realignment procedure: long-term follow-up

Purpose

To assess the long-term results of lateral facetectomy plus Insall’s realignment procedure to treat isolated patellofemoral osteoarthritis.

Methods

All consecutive patients undergoing this procedure with a follow-up between 10 and 14 years were included in this study. Subjects were excluded if they had previous patellar dislocation, patellar fracture, tibiofemoral osteoarthritis (except mild cases) or follow-up <10 or >14 years. Failure cases (need for total knee arthroplasty) of this surgical procedure before 10 years of follow-up were considered in the overall failure rate. Clinical, functional and radiographic outcomes were obtained at baseline and compared to postoperative values.

Results

Forty-three patients (mean (SD) age 59.7 (8.1) years) had a follow-up between 10 and 14 years and were finally included in this study. The failure rate in the whole series and included patients was 26.4 and 16.3 %, respectively, for a mean (SD) follow-up of 9.2 (3.2) years and 11.7 (1.4) years, respectively. Patellofemoral pain (p < 0.0001), need for NSAIDs (p < 0.0001), longitudinal (p < 0.0001) and transversal (p < 0.0001) patellar glide tests, Zholen’s sign (p = 0.0007) and knee effusion (p = 0.02) significantly improved in the follow-up. Postoperative Knee Society Score (KSS) anatomical (p < 0.0001), functional (p < 0.0001) and total (p < 0.0001) scores and Kujala’s score (p = 0.001) were significantly higher compared to preoperative values. The patellar tilt (p = 0.001) and shift (p = 0.04) significantly improved postoperatively, whereas the patellofemoral osteoarthritis was not modified (n.s.) with respect to preoperative assessment.

Conclusions

The lateral facetectomy plus Insall’s realignment procedure was a successful treatment for isolated patellofemoral osteoarthritis from a clinical, functional and radiographic point of view in the long-term follow-up.

Level of evidence

Prospective case series, Level IV.     

Medial patellofemoral ligament reconstruction as an isolated or combined procedure for recurrent patellar instability

Purpose

The principal aim of this study was to report the outcomes of medial patellofemoral ligament (MPFL) reconstruction, used as either an isolated procedure or in combination with another stabilization procedure, for the primary treatment of recurrent patellar instability.

Methods

Between 2007 and 2012, 45 patients with recurrent patellar instability and no prior stabilization surgery had an MPFL reconstruction by a single surgeon, either as an isolated procedure or in combination with another stabilization procedure. Questionnaires detailing patellar instability since surgery, knee pain, ability to negotiate stairs, and sports participation were completed, and data regarding examination and radiological findings were collected from the medical record.

Results

A total of 36 (80 %) patients completed the questionnaire at a mean of 3.1 years (minimum 1 year), whilst a further 11 % had clinical follow-up of greater than 1 year. Four patients were excluded due to lack of adequate follow-up. Thirty-one patients had an isolated MPFL reconstruction and none had further patellar instability. Of the ten patients who had a combined procedure, one experienced recurrent instability. Return to sport rates were 81 and 57 % for the isolated and combined groups, respectively, with the majority returning to strenuous sport (81 and 57 %, respectively). Most patients (96 and 80 %) could negotiate stairs without difficulty, whilst 38 and 40 % reported some degree of anterior knee pain.

Conclusions

This study shows that satisfactory results can be obtained using MPFL reconstruction either in isolation or in combination to treat recurrent patellar instability. Whether the indications for an isolated MPFL can be extended further remains unclear.

Level of evidence

III.     

Combined distal femoral osteotomy (DFO) in genu valgum leads to reliable patellar stabilization and an improvement in knee function

Purpose

Valgus deformities of the lower extremity influence patellofemoral joint kinematics. However, studies examining the clinical outcome after treatment of patellar instability and maltracking due to valgus deformity are rare in recent literature. This study’s purpose is to analyze the clinical results after combined distal femoral osteotomy (DFO) for treatment of patellar instability.

Methods

From 2010 to 2016, 406 cases of patellofemoral instability and maltracking were treated. Twenty cases of recurring (≥?2) patellar dislocations with genu valgum and unsuccessful conservative treatment were included in the study. A radiological analysis was performed, and anteroposterior (AP), lateral and long leg standing radiographs were analyzed, and the leg axis was pre- and postoperatively measured. At least 12 months postoperatively, the clinical leg axis, range of motion (ROM), apprehension sign, Zohlen sign, and J-sign were physically examined. Pain level and knee function were objectified on a visual analogue scale (VAS). The Lysholm, Kujala, and Tegner scores, re-dislocation rate, and patient satisfaction were also examined.

Results

20 combined DFOs on 18 patients with a median age of 23 years (15–55 years) were performed. The preoperative mechanical leg axis was 6.5°?±?2.0° valgus, and the mean tibial tuberosity to trochlear groove (TT-TG) distance was 19.1?±?4.8 mm. All patients reported multiple dislocations. Intraoperatively, 71% presented III°–IV° cartilage lesions, located retropatellarly in 87% and correlating negatively with the postoperative Lysholm score (r?=???0.462, p?=?0.040). The leg axis was corrected by 7.1°?±?2.6°, and in 17 cases, the tibial tubercle was additionally medialized by 10?±?3.1 mm. All patellae were re-stabilized with medial patellofemoral ligament reconstruction. After a median period of 16 (12–64) months, the pain level decreased from 8.0?±?1.4 to 2.3?±?2.1 (VAS p?≤?0.001) and knee function improved from 40.1?±?17.9 to 78.5?±?16.6 (Kujala p?≤?0.001), 36.1?±?19.5 to 81.6?±?11.7 (Lysholm p?≤?0.001), and 2.0 (1–5) to 4.0 (3–6) (median Tegner p?≤?0.001). No re-dislocation was observed.

Conclusion

Combined DFO is a suitable treatment for patellar instability and maltracking due to genu valgum, as it leads to very low re-dislocation rates, a significant reduction of pain, and a significant increase of knee function with good-to-excellent results in the short-term follow-up. However, a high prevalence of substantial cartilage lesions is observed, causing postoperative limitations of knee function.

Level of evidence

IV, retrospective cohort study.

     

Lateral release and medial plication for recurrent patella dislocation

Purpose

This study aims to report the long-term results of lateral release and medial plication in patients with recurrent patellar dislocation.

Methods

In this study, 31 patients who underwent surgery for recurrent patellar dislocation were retrospectively reviewed between 1994 and 2004. Among the 31 patients were 12 male and 19 female patients. The average age was 23.9?±?4.8?years, and the mean follow-up period was 11.6?±?2.4?years.

Results

Three patients had postoperative dislocations. The mean Kujala score significantly improved from 57.5?±?13.2 points preoperatively to 89.2?±?8.7 points at the final follow-up (P?<?0.0001). The median Tegner activity score significantly improved from 3 (range, 1?C5) at preoperative examination to 7 (range, 3?C9) at the final follow-up (P?<?0.0001). Ten patients were rated as excellent, 18 as good, 2 as fair, and 1 as poor. The congruence angle improved from 16.5°?±?3.0° to ?2.8°?±?2.7°, and the lateral patellofemoral angle improved from ?4.2°?±?1.9° to 8.2°?±?2.5°. There was no case of osteoarthritis at the final follow-up.

Conclusions

Percutaneous lateral release and medial plication showed satisfactory results with limited morbidity in the long-term follow-up. This traditional method remains a simple and effective surgical procedure for recurrent patellar dislocation.

Level of evidence

Therapeutic, Level IV.     

Combined trochleoplasty and MPFL reconstruction for treatment of chronic patellofemoral instability: a prospective minimum 2-year follow-up study

Purpose

Excessive trochlear dysplasia may be responsible for recurrent patellofemoral instability (PFI) due to a missing bony guidance for the patella in early flexion. Thus, an isolated medial patellofemoral ligament reconstruction (MPFLR) can be insufficient, since it mainly addresses instability close to extension and additionally can increase patellofemoral pressure leading to pain in flat or convex trochlear dysplasia. Therefore, in combination with a trochleoplasty, an anatomical trochlear groove is created, resulting in patellofemoral stability also in flexion, while patellofemoral pressure is normalized. In this prospective study, we evaluated the outcome of open trochleoplasty in combination with MPFLR with a minimum follow-up of 2 years for treatment of excessive PFI.

Methods

In between 2007 and 2009, 18 knees of 17 consecutive patients (mean age of 22.2 ± 4.9 years) with trochlear dysplasia type B, C or D according to Dejour et al. and positive apprehension from 0 to 60° of flexion were included. Tegner, Kujala and IKDC scores, apprehension and pain, trochlear dysplasia, sulcus angle, tibial tuberosity trochlear groove, patellar tilt and shift, Caton–Deschamps index as well as patellofemoral arthrosis according to the classification of Iwano et al. were assessed pre- and postoperatively.

Results

At a mean of 30.5 ± 5.9 months, all but one patient were subjectively satisfied with the outcome of the procedure, all showing absence of positive apprehension or redislocation. Significant (p < 0.001) reduction in pain (5.6 to 2.5 ± 2.8 points, VAS) and increase in Tegner (2, range 0–4 points to 6, range 3–8 points), Kujala (51.1 to 87.9 ± 20.0 points) and IKDC (49.5 to 80.2 ± 21.0 %) scores could be achieved. Radiologically significant (p < 0.02) improvement of patellofemoral positional parameters leading to more normal anatomy was recorded, while short-term arthrosis was absent.

Conclusions

Combined treatment for trochleoplasty with MPFLR serves as a successful therapy for chronic PFI. This combinatory treatment concept is a reliable option not only as salvage therapy but also as primary procedure regarding treatment for excessive PFI.

Level of evidence

Prospective case series, Level IV.