Visual-palpatory versus fluoroscopic intraoperative determination of the femoral entry point in medial patellofemoral ligament reconstruction

Comparison of five different fluoroscopic methods for identifying the MPFL femoral footprint

PURPOSE

The success of medial patellofemoral ligament (MPFL) reconstruction is closely linked to the precise positioning of the femoral tunnel. Intraoperative fluoroscopy is commonly utilized to identify the MPFL footprint. This study aimed to ascertain the most accurate fluoroscopic method among the five previously described methods used to determine the MPFL femoral footprint.

MATERIALS AND METHODS

Using 44 well-preserved dry femur bones, the MPFL femoral insertion site was demarcated using anatomical bony landmarks, namely the center of the saddle sulcus between the medial epicondyle, adductor tubercle and gastrocnemius tubercle. Fluoroscopic true lateral knee images were acquired and measurements taken, referencing established methods by Schottle et al., Redfern et al., Wijdicks et al., Barnett et al., and Kaipel et al. The distance between anatomic and fluoroscopic MPFL footprints was then measured on digital fluoroscopic images. The accuracy of the locations was compared using a margin of error of 5 and 7 mm.

RESULTS

The Schottle method consistently emerged superior, showcasing the smallest mean distance (3.2 ± 1.2 mm) between the anatomic and radiographic MPFL footprints and a high in-point detection rate of 90.9% under 5 mm criteria. While the Redfern method displayed perfect accuracy (100%) within the 7 mm criteria, the Schottle method also performed 97.7% accuracy.

CONCLUSIONS

For intraoperative identification of the MPFL footprint using fluoroscopy, the Schottle method is the most consistent and accurate among the assessed methods. Thus, its accuracy in detecting the MPFL footprint makes it recommended for MPFLR to ensure optimal outcomes.

LEVEL OF EVIDENCE

Level IV, cadaveric study.

Medium-term outcome of medial patellofemoral ligament reconstruction using synthetic graft

BACKGROUND

Recurrent patella instability is a common and debilitating condition which affects mainly adolescents and young adults. Medial patellofemoral ligament (MPFL) reconstruction is the most popular surgical treatment for recurrent patella instability. The most common graft choice in the literature is ipsilateral hamstring tendon (gracilis or semitendinosis) but the complication rate remains high (11-26%). Conversely, there are very few papers on the use of modern, synthetic grafts.

METHODS

A total of 85 patients who underwent MPFL reconstruction using a modern, synthetic graft (Xiros, UK) from 2014 to 2022 were retrospectively reviewed. Exclusion criteria were patella alta, malalignment, trochlea dysplasia and significant pain between episodes of instability. The author has developed an operative technique which is anatomic, minimally invasive and reproducible. Pre- and post-operative Kujala and Oxford knee scores were collected and analysed.

RESULTS

The male to female ratio was 27:58, the average age was 28 years, and the follow up range was 1-9 years (mean follow up 4.84 years). We found a statistically significant improvement in mean Kujala and Oxford knee scores (P < 0.001) postoperatively. No major complications such as knee stiffness, soft tissue reaction, re-dislocation, patella fracture were identified in the series. There were nine minor complications (10.6%): five cases of medial knee pain, two cases of residual instability and two of superficial infection.

CONCLUSION

This study demonstrates that modern, synthetic graft is a viable option for MPFL reconstruction. The technique described, achieves good clinical outcomes with low complication rates when compared with the published literature.

A Novel Technique of Arthroscopic Femoral Tunnel Placement during Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation

Recurrent patellar dislocation is a commonly encountered patellofemoral disease. Prompt surgical intervention is indicated for recurrent dislocation to restore patellofemoral stability. As one of the most preferred procedures, medial patellofemoral ligament (MPFL) reconstruction has been implemented on a large scale. Femoral tunnel placement remains a crucial technical issue during MPFL reconstruction and is critical to ensure the isometry and proper tension of the graft. Currently, visual-palpatory anatomic landmarks and fluoroscopy-guided radiographic landmarks comprise the main approaches to intraoperative femoral tunnel positioning. However, the accuracy of both methods has been questioned. This article introduces an arthroscopic femoral tunnel placement technique. Apart from traditional anteromedial and anterolateral portals, two auxiliary arthroscopic portals are specially designed. The adductor tubercle, the medial epicondyle and the posterior edge are selected as main anatomic landmarks and are directly visualized in sequence under arthroscope. The relative position between the femoral attachment of the MPFL and the three landmarks is measured on preoperative three-dimensional computed tomography, providing semi-quantified reference for intraoperative localization. This technique achieves minimally invasive tunnel placement without X-ray exposure, and especially suits obese patients for whom palpatory methods are difficult to perform.

Landmarks Used in Medial Patellofemoral Ligament Reconstruction Have Variable Topography

Purpose

To describe the morphology of the adductor tubercle (AT), medial epicondyle (ME), and gastrocnemius tubercle (GT); to quantify their relationships to the medial patellofemoral ligament (MPFL) footprint location; and to classify the reliability of each landmark based on measurement variability.

Methods

Eight cadaveric specimens were dissected to expose the following landmarks on the femur: MPFL footprint, AT, ME, and GT. Using the MicroScribe 3D digitizer, each landmark was projected into a 3-dimensional coordinate system and reconstructed into a complex, closed polygon. For each specimen tubercle, the base surface area, volume, height, base:height ratio, sulcus point, and distance from the MPFL footprint center were calculated. Levene's test was performed to evaluate differences in variance of the morphologic parameters between the three osseous structures.

Results

The ME had significantly greater variance in volume than the GT (P = .032), and the AT (17.5 ± 3.9) and GT (19.5 ± 3.6) were significantly less variable in base:height ratio than the ME (95.3 ± 19.2; P < .001). The GT was the closest to the MPFL footprint center (7.1 ± 3.1 mm) compared with the AT (13.4 ± 3.6 mm, P = .002) and ME (13.2 ± 2.7 mm, P = .003). However, the tubercles were equally variable in terms of distance to the MPFL footprint center (P = .86). Lastly, the sulcus point was estimated to be on average 1.9 ± 2.9 mm distal and 2.0 ± 2.0 mm posterior to the MPFL center point.

Conclusions

The 3 major osseous landmarks of the medial femur have significantly different variances in volume and base:height ratio. Specifically, the variability and elongated morphology of the ME differentiated this landmark from the AT and GT, which demonstrated the most consistent morphology.

Clinical Relevance

The results of this study may be useful to accurately locate landmarks for femoral tunnel placement and determine the isometric MPFL point during reconstruction.

Influence of the Fluoroscopy Setting towards the Patient When Identifying the MPFL Insertion Point

(1) The malposition of the femoral tunnel in medial patellofemoral ligament (MPFL) reconstruction can lead to length changes in the MPFL graft, and an increase in medial peak pressure in the patellofemoral joint. It is the cause of 36% of all MPFL revisions. According to Schöttle et al., the creation of the drill canal should be performed in a strictly lateral radiograph. In this study, it was hypothesized that positioning the image receptor to the knee during intraoperative fluoroscopy would lead to a relevant mispositioning of the femoral tunnel, despite an always adjusted true-lateral view. (2) A total of 10 distal femurs were created from 10 knee CT scans using a 3D printer. First, true-lateral fluoroscopies were taken from lateral to medial at a 25 cm (LM25) distance from the image receptor, then from medial to lateral at a 5 cm (ML5) distance. Using the method from Schöttle, the femoral origin of the MPFL was determined when the femur was positioned distally, proximally, superiorly, and inferiorly to the image receptor. (3) The comparison of the selected MPFL insertion points according to Schöttle et al. revealed that the initial determination of the point in the ML5 view resulted in a distal and posterior shift of the point by 5.3 mm ± 1.2 mm when the point was checked in the LM25 view. In the opposite case, when the MPFL insertion was initially determined in the LM25 view and then redetermined in the ML5 view, there was a shift of 4.8 mm ± 2.2 mm anteriorly and proximally. The further positioning of the femur (distal, proximal, superior, and inferior) showed no relevant influence. (4) For fluoroscopic identification of the femoral MPFL, according to Schöttle et al., attention should be paid to the position of the fluoroscopy in addition to a true-lateral view.

Femoral tunnel malposition is the most common indication for revision medial patellofemoral ligament reconstruction with promising early outcomes following revision reconstruction: a systematic review

PURPOSE

The purpose of this study was to identify the causes of failure of previous medial patellofemoral ligament reconstruction (MPFL-R), and to furthermore report the surgical techniques available for MPFL revision surgery.

METHODS

Four databases [PubMed, Ovid (MEDLINE), Cochrane Database, and EMBASE] were searched until September 29, 2020 for human studies pertaining to revision MPFL. Two reviewers screened the literature independently and in duplicate. Methodological quality of the included studies was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria, or the CAse REport guidelines (CARE), where appropriate.

RESULTS

Fourteen studies (one level II, one level III, two level IV, ten level V) were identified. This search resulted in a total of 76 patients with a mean age (range) of 22 (14-39) years. The patients were 75% female with a mean (range) time to revision of 24.1 (1-60) months and mean (range) follow-up of 36.2 (2-48) months. The most common indication for revision surgery was malpositioning of the femoral tunnel (38.1%), unaddressed trochlear dysplasia (18.4%), patellar fracture (11.8%). Femoral tunnel malposition was typically treated via revision MPFL-R with quadriceps tendon or semitendinosus autograft and may retain the primary graft if fixation points were altered. Unaddressed trochlear dysplasia was treated with deepening trochleoplasty with or without revision MPFL-R, and patella fracture according to the nature of the fracture pattern and bone quality. Though generally, outcomes in the revision scenario across all indications were inferior to those post-primary procedure, overall, revision patients demonstrated positive improvements in pain and instability symptoms. Transverse patella fractures treated with debridement and filling with demineralized bone matrix if required with further fixation according to the fracture pattern.

CONCLUSION

The most common causes of MPFL failure in literature published to date, in order of decreasing frequency, are: malposition of the femoral tunnel, unaddressed trochlear dysplasia, and patellar fracture. Although surgical techniques of revision MPFL-R to manage these failures were varied, promising outcomes have been reported to date. Larger prospective comparative studies would be useful to clarify optimal surgical management of MPFL-R failure at long-term follow-up.

LEVEL OF EVIDENCE

IV.

[Research progress in femoral tunnel positioning points of medial patellofemoral ligament reconstruction]

Objective

To review the research progress of location methods and the best femoral insertion position of medial patellofemoral ligament (MPFL) reconstruction of femoral tunnel, and provide reference for surgical treatment.

Methods

The literature about femoral insertion position of the MPFL reconstruction in recent years was extensively reviewed, and the anatomical and biomechanical characteristics of MPFL, as well as the advantages and disadvantages of femoral tunnel positioning methods were summarized.

Results

The accurate establishment of the femoral anatomical tunnel is crucial to the success of MPFL reconstruction. At present, there are mainly two kinds of methods for femoral insertion: radiographic landmark positioning method and anatomical landmark positioning method. Radiographic landmark positioning method has such advantages as small incision and simple operation, but it can not be accurately positioned for patients with severe femoral trochlear dysplasia. It is suggested to combine with the anatomical landmark positioning method. These methods have their own advantages and disadvantages, and there is no unified positioning standard. In recent years, the use of three-dimensional design software can accurately assist in the MPFL reconstruction, which has become a new trend.

Conclusion

Femoral tunnel positioning of the MPFL reconstruction is very important. The current positioning methods have their own advantages and disadvantages. Personalized positioning is a new trend and has not been widely used in clinic, its effectiveness needs further research and clinical practice and verification.

Radiographic Reference Points Do Not Ensure Anatomic Femoral Fixation Sites in Medial Patellofemoral Ligament Reconstruction: A Quantified Anatomic Localization Method Based on the Saddle Sulcus

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is one of the main treatments for lateral patellar translation. Based on intraoperative true lateral radiographs, the accepted methods for femoral MPFL tunnel location are potentially inaccurate. Direct assessment of anatomic characteristics during surgery through palpation of the anatomic landmarks involving the saddle sulcus might help eliminate tunnel malposition.

HYPOTHESIS

The saddle sulcus is a reliable osseous landmark where the MPFL attaches for tunnel placement.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 9 fresh-frozen unpaired human cadaveric knees were dissected; MPFL insertion point and relative osseous structures were marked. Three-dimensional images and transformed true lateral radiographs were obtained for analysis; 3 previously reported radiographic reference points for MPFL femoral tunnel placement were determined on all images and compared with the anatomic insertion.

RESULTS

A saddle sulcus consistently existed where the MPFL was attached, located at 11.7 ± 5.9 mm from the apex of the adductor tubercle (AT) to the medial epicondyle (ME), 62.8% of the average distance between the apexes of the AT and ME, and 5.6 ± 2.8 mm perpendicular-posterior to the border connecting the AT and ME. The reported radiographic reference points were located at average distances of 6.2 ± 3.2 mm (Schöttle method), 5.9 ± 2.3 mm (Redfern method), and 7.3 ± 6.6 mm (Fujino method) from the saddle sulcus center on the true lateral radiographs.

CONCLUSION

The saddle sulcus was a reliable landmark where the MPFL was anatomically attached, located approximately 12 mm from the AT to the ME (approximately 60% along a line from the AT to the ME) and 6 mm perpendicular-posterior to the border connecting the apexes of the AT and ME. Additionally, the saddle sulcus position presented variability on the femoral aspect of different knees. All of the average direct distances from the sulcus to the reference radiographic points exceeded 5 mm, and tunnel localizations on a true lateral radiograph were inaccurate.

CLINICAL RELEVANCE

This study demonstrates the potential precise position of the saddle sulcus, according to the ME and AT, as a reliable anatomic landmark for MPFL femoral tunnel location. Radiographic reference points were not accurate during MPFL reconstruction. Direct palpation of the landmarks might be effective for femoral MPFL tunnel placement.

Validity of intraoperative observation of graft length change pattern for medial patellofemoral ligament reconstruction

Background

The clinical outcome of the medial patellofemoral ligament reconstruction (MPFLR) based on graft length change pattern (length pattern group) was compared with MPFLR based on visual examination combined with palpation (visual/palpation group).

Methods

Physical findings, patient-reported outcome, and radiographic demonstration were evaluated pre- and postoperatively.

Results

The length pattern group had significantly lower risk of a positive apprehension test (Odds ratio 0.12, p < 0.01), and higher scores in postoperative Lysholm score (p = 0.046) and patient satisfaction (p = 0.036) than The visual/palpation group.

Conclusion

MPFLR based on graft length change pattern improved on patient-reported outcomes and apprehension test.

Level of evidence

Level Ⅲ, Retrospective comparative study.

Radiographic images are inapplicable for a precise evaluation of the femoral tunnel position following MPFL reconstruction

PURPOSE

In medial patellofemoral ligament (MPFL) reconstruction, it remains controversial whether more accurate femoral tunnel positioning is correlated with improved clinical outcomes. The purpose was to verify the accuracy of methods for evaluating tunnel positioning, one of which is the use of postoperative radiographs, in determining the femoral tunnel position following MPFL reconstruction and to compare the variability of tunnel positions to the intraoperatively documented positions on a true-lateral view.

METHODS

Seventy-three consecutive MPFL reconstructions were prospectively enrolled. Femoral tunnel positions were intraoperatively determined using fluoroscopy to obtain true-lateral radiographs. Postoperatively, lateral radiographic images were taken. Seven independent radiologists and seven independent orthopaedic knee surgeons evaluated the femoral tunnel position and amount of malrotation for each radiograph. Deviations from the Schoettle's point were measured and repeated after 4 weeks. Intraobserver and interobserver analyses of variance were calculated to determine the reliability of measurements on both intraoperative and postoperative radiographs.

RESULTS

Fifty-six patients were included in the final analysis. Tunnel positions were unable to be identified on postoperative radiographs in 14% of cases on average, independent of the degree of radiograph rotation. Intraoperative images showed mean deviations from the tunnel position to the centre of Schoettle's point of 1.9 ± 1.4 mm and 1.6 ± 1.0 mm in anterior-posterior and proximal-distal direction, respectively. Postoperative radiographs showed mean anterior-posterior and deviations of 7.4 ± 4.4 mm and 8.9 ± 5.8 mm assessed by orthopaedic surgeons and 10.6 ± 6.3 mm and 11.6 ± 7.1 mm assessed by radiologists at first and repeated measurement, respectively. The mean proximal-distal deviations were 4.8 ± 4.4 mm and 6.5 ± 6.0 mm and 7.2 ± 6.3 mm and 8.1 ± 7.1 mm, respectively. Measurement of tunnel position on intraoperative fluoroscopic images was significantly different compared to postoperative radiographs for each of the 14 observers (p < 0.05). Significant intraobserver and interobserver differences between the first and repeat measurements for both orthopaedic surgeons and radiologists were observed (p < 0.05).

CONCLUSION

Measurement of the femoral tunnel position on postoperative lateral radiographs is not an accurate or reliable method for evaluating tunnel position after MPFL reconstruction due to exposure, contrast, and malrotation of the radiograph from a true-lateral image. In contrast, intraoperative fluoroscopic control allows for a precise lateral view and correct tunnel positioning. Thus, postoperative radiographic images may be unnecessary for the evaluation of femoral tunnel positions, particularly when intraoperative fluoroscopy has been used.

STUDY DESIGN

Level II, prospective cohort study.

Comparation and evaluation of the accuracy of the sulcus localization method to establish the medial patellofemoral ligament femoral tunnel: a cadaveric and clinical study

Background

In anatomic medial patellofemoral ligament (MPFL) reconstruction, malpositioning of the MPFL femoral tunnel is common. A palpable sulcus reportedly exists at the anatomic femoral attachment of the MPFL. The present study aimed to investigate the accuracy of the sulcus localization method to establish the MPFL femoral tunnel.

Methods

A cadaveric study was first done on 12 knees to evaluate the accuracy of the sulcus localization method to establish the entry points of the MPFL femoral tunnel in comparison with the midpoint and fluoroscopic localization methods. The center of the native MPFL femoral attachment was served as the reference in the cadaveric study. A clinical study was then performed to further evaluate the accuracy of the sulcus localization method in 53 patients (60 knees). Schöttle’s point was served as the reference in the clinical study. Femoral tunnel placement was defined as accurate when it was less than 5 mm from Schöttle’s point. In both the cadaveric and clinical studies, MPFL femoral tunnel placement was assessed on postoperative reconstructed three-dimensional computed tomography images. In the cadaveric study, the accuracy of different localization methods was compared using analysis of variance.

Results

In the cadaveric study, the mean distances from the native MPFL attachment to the femoral tunnel entry point were 4.2 ± 1.0 mm (range 2.4–5.6 mm), 4.4 ± 1.4 mm (range 1.8–6.6 mm) and 2.9 ± 0.8 mm (range 1.9–4.4 mm) using the midpoint, fluoroscopic, and sulcus localization methods, respectively; this distance significantly differed between the midpoint and sulcus localization methods, and between the fluoroscopic and sulcus localization methods (p ≤ .05). While there were no significant differences between the midpoint and fluoroscopic localization methods (n.s.). In the clinical study, the mean distance between the femoral tunnel and Schöttle’s point was 3.5 ± 1.5 mm (range 0.4–6.1 mm), with accurate tunnel placement achieved in 49 of 60 cases (82%).

Conclusion

The sulcus localization method can accurately guide MPFL femoral tunnel placement. This method might be useful for orthopedic surgeons.

Level of evidence

IV

Intraoperative fluoroscopy during MPFL reconstruction improves the accuracy of the femoral tunnel position

PURPOSE

Reconstruction of the medial patellofemoral ligament (MPFL) has been established as standard of care for patellofemoral instability. An anatomic femoral tunnel position has been shown to be a prerequisite for restoration of patellofemoral stability and biomechanics. However, the incidence of malpositioning of the femoral tunnel during MPFL reconstruction continues to be notable. Palpation of anatomic landmarks and intraoperative fluoroscopy are the two primary techniques for tunnel placement. The aim of this study was to compare the accuracy of these two methods for femoral tunnel placement.

METHODS

From 2016 to 2017, 64 consecutive patients undergoing MPFL reconstruction for patelllofemoral instability were prospectively enrolled. During surgery, the presumed femoral MPFL insertion was identified by both palpation of anatomic landmarks and using fluoroscopy, both of these points were separately documented on true lateral radiographs. They were then analysed and deviations from the Schoettle's Point were measured as anterior-posterior and proximal-distal deviations. A tunnel position within a radius of 7 mm around the Schoettle's Point was designated as an "accurate tunnel position".

RESULTS

Compared to the method of palpation, fluoroscopy led to significantly more anatomic femoral tunnel positoning (p < 0.0001). The mean proximal-distal and anterior-posterior distances between the femoral insertion site identified by palpation and the Schoettle's Point were 5.7 ± 4.5 mm (0.3-20.3 mm) and 4.1 ± 3.7 mm (0.1-20.3 mm), respectively, versus 1.7 ± 0.9 mm (0.1-3.6 mm) and 1.8 ± 1.3 mm (0.1-4.8 mm) for fluoroscopy, respectively. Using fluoroscopy, all femoral insertion sites were identified within a 7 mm radius around the centre of the Schoettle's Point. In contrast, only 52% (33) of femoral insertion sites identified by palpation were within this radius. These data were independent of patients' age, gender and BMI. No improvement in accuracy of femoral tunnel positions was detected over time.

CONCLUSIONS

The main finding of this study was that, compared to the method of palpation of anatomic landmarks, the use of intraoperative fluoroscopy in MPFL reconstruction leads to more accurate femoral tunnel positioning. Based on these results, the use of intraoperative fluoroscopy has to be recommended for femoral tunnel placement in daily surgical practice to minimize the incidence of malpositioning and to restore native patellofemoral biomechanics.

STUDY DESIGN

Level III Case-control study.

Effective patellofemoral joint stabilization and low complication rates using a hardware-free MPFL reconstruction technique with an intra-operative adjustment of the graft tension

PURPOSE

Even if medial patellofemoral ligament (MPFL) reconstruction is a proven method, complications such as implant loosening, patella fractures, recurrent luxations, knee pain or knee stiffness are frequently described. Besides a correct tunnel positioning and implant-specific complications, this might be caused by difficulties with an appropriate graft tensioning. The study presented here is a necessary first step in exploring our technique of a double-limbed, hardware-free MPFL reconstruction, which provides another way to test and adjust the graft tension before permanent fastening.

METHODS

Thirty consecutive patients (m/f = 18/12) with recurrent dislocations were evaluated after a mean follow-up of 24 months. Patients who had additional procedures such as a trochleoplasties, tibial tubercle transfers and derotational osteotomies were not included. Besides a standardized clinical examination, different scorings and possible complications were evaluated.

RESULTS

The mean Kujala score improved significantly from 57 ± 15 to 92 ± 10. The Lysholm and IKDC score increased significantly from 59 ± 11 to 95 ± 6 and from 49 ± 9 to 89 ± 9, respectively. No patient reported a re-dislocation, subluxation or showed a positive apprehension. A total of 23 patients were engaged in regular physical activities. All but one, who lost interest, returned to the same sports. Because some did not follow our recommendation to return to sports after a rehab of at least 10-12 weeks, the period for a return was relatively short (median of 12 weeks, range 3-25 weeks). Four patients reported a moderate anterior knee pain only occurring after increased loads such as longer runs or workouts. One of these showed a slight flexion deficit of less than 20°. A severe motion deficit or stiffness was not noticed.

CONCLUSIONS

Even if a larger, clinical outcome study is needed to ensure the efficacy and safety of our method, it seems to provide a good clinical outcome, a correspondingly high satisfaction and a low incidence of complications. The possibility to adjust graft tension might help in minimizing complications caused by difficulties with an appropriate graft tension.

LEVEL OF EVIDENCE

IV.

The Relationship of Femoral Tunnel Positioning in Medial Patellofemoral Ligament Reconstruction on Clinical Outcome and Postoperative Complications

PURPOSE

To analyze the relation of the femoral tunnel (FT) positioning on clinical outcome.

METHODS

Patients with recurrent patellar dislocation who underwent medial patellofemoral ligament (MPFL) reconstruction with or without tibial tubercle osteotomy between 1998 and 2012 were included in this retrospective study. Strict postoperative lateral radiographs were mandatory. Knees with previous osseous stabilization surgery, fixed lateral patellar dislocation, valgus knee (>5°), or open growth plates were excluded. The distance between the FT and the validated radiographic landmark (the "Schoettle point") was measured. An FT with a distance greater than 10 mm was considered as malpositioned. The distance was correlated to subjective outcome measurements (patient satisfaction and Kujala score) and postoperative complications (a loss of range of motion and revision surgery).

RESULTS

Sixty-three knees in 60 patients (aged 23.7 ± 7.5 years at the time of surgery, 79.4% female) were included with a mean follow-up of 5.7 ± 3.3 years. The FT showed an average distance of 13.3 mm (±6.0 mm; 95% confidence interval [CI]: 11.7-14.8) to the Schoettle point, and 45 of 63 knees (71.4%) were deemed malpositioned. The postoperative Kujala score of malpositioned FT (75.9 points; 95% CI: 71.2-80.7) was not significantly inferior to knees with an FT within 10 mm (80.5; 95% CI: 73.7-87.3, P = .315). However, all 5 knees that underwent revision surgery showed an FT outside the 10-mm area.

CONCLUSIONS

Malpositioning of the FT in MPFL reconstruction is associated with postoperative complications. However, a malpositioned FT in MPFL reconstruction will not necessarily lead to an unsatisfactory subjective or objective clinical outcome. Other factors, such as surgical indication or graft tensioning, might also significantly influence postoperative outcome.

LEVEL OF EVIDENCE

Level IV, case-control study.

Clinical outcomes after revision surgery for medial patellofemoral ligament reconstruction

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is the standard surgical intervention for patella instability. However, limited knowledge exists concerning the causes for failure, and outcome after revision MPFL-R. The purpose of this study is to evaluate the causes of primary MPFL-R failure and clinical outcomes after revision MPFL-R.

METHODS

Twenty-three patients (6 males and 17 females) with failed primary MPFL-R underwent isolated revision MPFL-R or combined revision MPFL-R with tibial tuberosity osteotomy (TTO). The mean age was 23 (SD 8.6). Prior to surgery, dysplasia of the patellofemoral joint, sulcus angle, Insall-Salvati index, cartilage lesions, tibial tuberosity trochlear groove (TTTG) distance, and tunnel placement were evaluated by magnetic resonance imaging (MRI). Their scores on the Kujala Anterior Knee Pain Scale and pain scores were assessed prior to surgery, 1 year post-operatively and at final follow-up. The mean follow-up time was 44 months (median range 39). The radiographic characteristics and clinical outcomes were compared with a 224 primary MPFL-R patient cohort (240 knees).

RESULTS

Non-anatomical fixation of the graft at the medial femoral condyle after primary MPFL-R was seen in 67% of revision patients with anterior/proximal misplacement in most cases. Severe trochlear dysplasia Dejour types C and D were seen in 36% of the patients compared to 30% of primary MPFL-R patients (NS). The mean Kujala Anterior Knee Pain Scale score at final follow-up was 61.7 (SD 18.8) compared to 80.3 (SD 18) in primary MPFL-R patients (P < 0.01). The mean pain score at rest was 2.3 (SD 2.5) for revision MPFL-R patients compared to 1.7 (SD 2.5) in primary MPFL-R patients (NS) and their mean pain score during activity was 5.0 (SD 3.2) compared to 1.3 (SD 2.2) in primary MPFL patients (P < 0.001).

CONCLUSION

Although revision MPFL-R establishes acceptable patellar stability, the subjective outcomes after revision MPFL-R do not improve significantly, and are poorer than after primary MPFL-R. Non-anatomical graft position can be an important cause of MPFL-R failure. The clinical relevance of this study is that it shows that it may be difficult to improve self-reported outcomes in revision MPFL-R patients.

LEVEL OF EVIDENCE

III.

Medial Patellofemoral Ligament Reconstruction Using Dual Patella Docking Technique

Medial patellofemoral ligament (MPFL) injuries are common in children and young adults. In patients with recurrent patellar dislocations with normal lower-extremity alignment, anatomic reconstruction of the MPFL has been shown to restore patellar stability. We describe a technique that creates an anatomic reconstruction using a dual docking technique into the patella. Our technique is simple and efficacious for reconstructing the MPFL without implant fixation in the patella, allowing a maximal bone-tendon interface for healing.

Assessment of the Isometry of the Anterolateral Ligament in a 3-Dimensional Weight-Bearing Computed Tomography Simulation

PURPOSE

To simulate the most isometric insertion points of the anterolateral ligament (ALL) in a weight-bearing 3-dimensional computed tomography (CT) model using previously published anatomic landmarks and to define radiographic landmarks, which make for an easier identification of the optimal insertion points.

METHODS

The most isometric femoral insertion points were analyzed for 10 individuals, using data of weight-bearing CT scans in increasing knee flexion positions. An automatic string generation algorithm helped identify isometrically optimal points using an isometric score (0 indicating optimal isometry). Subsequently, a general femoral insertion point was determined, which preserved the isometry in all tested individuals. Based on the femoral insertion point, we assessed the influence of varying tibial insertion points on the isometric behavior of the ALL.

RESULTS

The defined femoral insertion point, which preserved the isometry in all analyzed individuals, had a median isometric score between 0.167 × 10^-3 and 0.559 × 10^-3. The average distance from the most prominent point of the lateral epicondyle was 9.7 mm (standard deviation [SD], 1.6) in a straight superior direction. In a straight lateral radiographic view, this point is located exactly at the intersection of a tangent set between the posterior cortex of the femur and a second perpendicular line intersecting at the level of the most (superior-) posterior point of the Blumensaat line. The best isometric behavior was found on the anatomically defined mean tibial insertion point, located at 37% of the width of the tibial plateau, which worsened gradually if corrected to anterior or posterior.

CONCLUSIONS

We determined femoral and tibial insertion points as well as radiographic landmarks for the reconstruction of the ALL that are based on published anatomic descriptions and preserve isometry in all analyzed individuals in this study.

CLINICAL RELEVANCE

This study provides new information, which might be helpful to define isometrically optimal insertion points for ALL reconstruction.

Medial Patellofemoral Ligament Reconstruction Femoral Tunnel Accuracy: Relationship to Disease-Specific Quality of Life

Background:

Medial patellofemoral ligament (MPFL) reconstruction is a procedure aimed to reestablish the checkrein to lateral patellar translation in patients with symptomatic patellofemoral instability. Correct femoral tunnel position is thought to be crucial to successful MPFL reconstruction, but the accuracy of this statement in terms of patient outcomes has not been tested.

Purpose:

To assess the accuracy of femoral tunnel placement in an MPFL reconstruction cohort and to determine the correlation between tunnel accuracy and a validated disease-specific, patient-reported quality-of-life outcome measure.

Study Design:

Case series; Level of evidence, 4.

Methods:

Between June 2008 and February 2014, a total of 206 subjects underwent an MPFL reconstruction. Lateral radiographs were measured to determine the accuracy of the femoral tunnel by measuring the distance from the center of the femoral tunnel to the Schöttle point. Banff Patella Instability Instrument (BPII) scores were collected a mean 24 months postoperatively.

Results:

A total of 155 (79.5%) subjects had adequate postoperative lateral radiographs and complete BPII scores. The mean duration of follow-up (±SD) was 24.4 ± 8.2 months (range, 12-74 months). Measurement from the center of the femoral tunnel to the Schöttle point resulted in 143 (92.3%) tunnels being categorized as “good” or “ideal.” There were 8 failures in the cohort, none of which occurred in malpositioned tunnels. The mean distance from the center of the MPFL tunnel to the center of the Schöttle point was 5.9 ± 4.2 mm (range, 0.5-25.9 mm). The mean postoperative BPII score was 65.2 ± 22.5 (range, 9.2-100). Pearson r correlation demonstrated no statistically significant relationship between accuracy of femoral tunnel position and BPII score (r = –0.08; 95% CI, –0.24 to 0.08).

Conclusion:

There was no evidence of a correlation between the accuracy of MPFL reconstruction femoral tunnel in relation to the Schöttle point and disease-specific quality-of-life scores. Graft failure was not related to femoral tunnel placement. The patellofemoral instability population is complex, and patients present with multiple risk factors that, in addition to the accuracy of femoral tunnel position, contribute to quality of life and warrant further investigation.