Medial patellofemoral ligament reconstruction: A review

The thickness change ratio and preservation ratio of the infrapatellar fat pad are related to anterior knee pain in patients following medial patellofemoral ligament reconstruction

BACKGROUND

The infrapatellar fat pad (IPFP) lies extrasynovial and intracapsular, preserving the joint cavity and serving as a biochemical regulator of inflammatory reactions. However, there is a lack of research on the relationship between anterior knee pain (AKP) and the IPFP after medial patellofemoral ligament reconstruction (MPFLR). Pinpointing the source of pain enables clinicians to promptly manage and intervene, facilitating personalized rehabilitation and improving patient prognosis.

METHODS

A total of 181 patients were included in the study. These patients were divided into the AKP group (n = 37) and the control group (n = 144). Clinical outcomes included three pain-related scores, Tegner activity score, patient satisfaction, etc. Imaging outcomes included the IPFP thickness, IPFP fibrosis, and the IPFP thickness change and preservation ratio. Multivariate analysis was used to determine the independent factors associated with AKP. Finally, the correlation between independent factors and three pain-related scores was analyzed to verify the results.

RESULTS

The control group had better postoperative pain-related scores and Tegner activity score than the AKP group (P < 0.01). The AKP group had lower IPFP thickness change ratio and preservation ratio (P < 0.001), and smaller IPFP thickness (P < 0.05). The multivariate analysis revealed that the IPFP thickness change ratio [OR = 0.895, P < 0.001] and the IPFP preservation ratio [OR = 0.389, P < 0.001] were independent factors related to AKP, with a significant correlation between these factors and pain-related scores [|r| > 0.50, P < 0.01].

CONCLUSIONS

This study showed the lower IPFP change ratio and preservation ratio may be independent factors associated with AKP after MPFLR. Early detection and targeted intervention of the underlying pain sources can pave the way for tailored rehabilitation programs and improved surgical outcomes. LEVEL OF EVIDENCE LEVEL III.

Nonanatomical femoral tunnel positioning in isolated MPFL reconstruction is not associated with an increased risk of patellofemoral osteoarthritis after a minimum follow-up of 10 years

PURPOSE

The association between the prevalence of patellofemoral arthritis (PFA) and femoral tunnel positioning following isolated medial patellofemoral ligament reconstruction (MPFLr) has not been well described. The aim of this study was to analyse the relationship between femoral tunnel positioning and the prevalence of PFA.

METHODS

This was a single-centre study of patients undergoing an isolated MPFLr between 2006 and 2011 with a minimum of 10 years of follow-up. Outcomes assessed were the presence of PFA on radiographs, recurrence of instability requiring revision surgery and patient-reported outcomes, including Kujala, Tegner and IKDC scores. Tunnel positioning was assessed on postoperative radiographs using two radiographic methods: Schöttle's point and the grid method to localise the femoral tunnel. Patients were grouped based on tunnel positioning and compared.

RESULTS

Fifty patients were analysed at a mean follow-up of 12.4 years. Thirty-three patients (66%) had a femoral tunnel position within 7 mm of Schöttle's point and 39 (78%) within the anatomic quadrant, with the most common location according to the grid method in D4 (28%) and E4 (26%), respectively. Thirty-seven patients (74%) had a satisfactory (>80 versus <80) Kujala score at long-term follow-up. None of the examined tunnel assessment methods demonstrated a significant relationship with Tegner, Kujala or International Knee Documentation Committee scores. Patients with a femoral tunnel position >7 mm outside Schöttle's point or were considered to be in a nonanatomic position were not significantly more likely to result in unsatisfactory Kujala scores at the last follow-up. Tunnel positioning and the other tested parameters were not found to be significantly associated with the development of PFA.

CONCLUSION

No correlation between femoral tunnel position and risk of PFA or poor outcomes was observed in patients undergoing isolated MPFLr at long-term follow-up. The impact of femoral tunnel placement on long-term outcomes in patients with PFI may be less significant than originally considered.

LEVEL OF EVIDENCE

Level IV.

Length Changes of the Medial Patellofemoral Ligament During In Vivo Knee Motion: An Evaluation Using Dynamic Computed Tomography

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is associated with high complication rates because of graft overloading from incorrect graft positioning. To improve clinical outcomes, it is crucial to gain a better understanding of MPFL elongation patterns.

PURPOSE

To assess MPFL length changes in healthy knees from 0° to 90° of dynamic flexion and their relationship with anatomic parameters of the patellofemoral joint.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Dynamic computed tomography scans of an active flexion-extension-flexion movement in 115 knees from 63 healthy participants were evaluated to construct knee joint models. Using these models, the MPFL length was measured as the shortest wrapping path from the Schöttle point on the femur to 3 insertion points on the superomedial border of the patella (proximal, central, and distal). MPFL length changes (%) relative to the length in full extension were calculated, and their correlations with the tibial tuberosity-trochlear groove distance, Caton-Deschamps index, and lateral trochlear inclination were analyzed.

RESULTS

The proximal fiber was the longest in full extension and progressively decreased to a median length of -6.0% at 90° of flexion. The central fiber exhibited the most isometric pattern during knee flexion, showing a median maximal decrease of 2.8% relative to the full extension length and no evident elongation. The distal fiber first slightly decreased in length but increased at deeper flexion angles. The median overall length changes were 4.6, 4.7, and 5.7 mm for the proximal, central, and distal patellar insertion, respectively. These values were either not or very weakly correlated with the tibial tuberosity-trochlear groove distance, Caton-Deschamps index, and lateral trochlear inclination when the anatomic parameters were within the healthy range.

CONCLUSION

The median MPFL length changed by approximately 5 mm between 0° and 90° of flexion. Proximally, the length continuously decreased, indicating slackening behavior. Distally, the length increased at deeper flexion angles, indicating tightening behavior.

CLINICAL RELEVANCE

In MPFL reconstruction techniques utilizing the Schöttle point to establish the femoral insertion, one should avoid distal patellar insertion, as it causes elongation of the ligament, which may increase the risk for complications due to overloading.

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.

Surgical techniques for medial Patellofemoral ligament reconstruction: a systematic review and meta-analysis of level I and II studies

PURPOSE

To determine the most optimal surgical technique for medial patellofemoral ligament reconstruction (MPFLR).

METHODS

Three databases MEDLINE, PubMed, and EMBASE were searched from inception to December 13th, 2022, for level I or II studies comparing MPFLR techniques. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on patient-reported outcome measures were recorded. Quality assessment was carried out using the MINORS and Cochrane Risk of Bias assessment tools. Certainty of evidence was carried out with the GRADE assessment tool.

RESULTS

Ten studies comprising 723 patients (723 knees) were included in this review. The weighted mean difference in Kujala, Lysholm, and IKDC scores comparing single- and double-tunnel patellar drilling techniques was 2.66 (95% CI -1.05-6.37, p = 0.16, I2 = 0%) with moderate certainty, 0.78 (95% CI -9.02-10.58, p = 0.88, I2 = 87%) with low certainty, and 1.71 (95% CI -2.43-5.86, p = 0.42, I2 = 0%) with low certainty, respectively. Double-suture anchor patellar fixation demonstrated greater Kujala scores than transpatellar fixation (87.1 ± 2.8 vs 84.0 ± 3.8, p < 0.001) with moderate certainty. Y-shaped graft patellar fixation demonstrated superior Kujala scores to C-shaped graft patellar fixation (95.9 ± 4.7 vs 91.3 ± 9.7, p = 0.001) with moderate certainty. Augmentation of femoral fixation with polyester sutures demonstrated superior Kujala scores (97.8 ± 6.4. vs 88.0 ± 6.3, p < 0.005) with low certainty. Four-stranded grafts demonstrated greater Kujala scores than two-stranded grafts (93.5 ± 2.6 vs 91.6 ± 3.5, p = 0.01) with low certainty.

CONCLUSION

The optimal MPFLR surgical technique is likely to utilize a four-stranded graft using either endobutton, double-suture anchor, or transosseous suture patellar fixation with polyester suture augmented interference screw femoral fixation. Orthopedic surgeons can consider employing such a technique to improve patient outcomes by conferring greater graft stability, strength, and function. Level of evidence Level II.

The adductor magnus tendon is a viable option for medial patellofemoral ligament reconstruction, but with a busy surrounding neurovascular topography

PURPOSE

To describe the proximity of the neurovascular structures surrounding the adductor magnus (ADM), to delineate a safe boundary focusing on the techniques used during graft harvest and to evaluate whether the length of the ADM tendon is sufficient for safe medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Sixteen formalin-fixed cadavers were dissected. The area surrounding the ADM, the adductor tubercle (AT) and the adductor hiatus was exposed. The following measurements were performed: the (1) total length of MPFL, (2) distance between the AT and the saphenous nerve, (3) the point where the saphenous nerve pierces the vasto-adductor membrane, (4) the point where the saphenous nerve crosses the ADM tendon, (5) the musculotendinous junction of the ADM tendon, and (6) the point where the vascular structures exit the adductor hiatus. Additionally, (7) the distance between the ADM musculotendinous junction and the nearest vessel (popliteal artery), (8) the distance between the ADM (at the level where the saphenous nerve crosses) and the nearest vessel, (9) the length between the AT and the superior medial genicular artery, and finally (10) the depth between the AT and the superior medial genicular artery were analyzed.

RESULTS

The in situ length of the native MPFL was 47.6 ± 42.2 mm. The saphenous nerve pierces the vasto-adductor membrane at a mean distance of 100 mm, although it crosses the ADM itself at an average of 67.6 mm. The vascular structures, on the other hand, become vulnerable at a distance of 89.1 ± 114.0 mm from the AT. After harvesting the ADM tendon, the mean length was found to be 46.9 mm, which was insufficient for fixation. Partial release from the AT resulted in a more adequate length for fixation (65.4 ± 88.7 mm).

CONCLUSION

The adductor magnus tendon is a viable option for the dynamic reconstruction of the MPFL. Knowledge of the surrounding busy neurovascular topography is paramount for a procedure typically performed in a minimally invasive way. The study results are clinically relevant, as they suggest that tendons should be shorter than the minimum distance from the nerve. If in some cases the length of the MPFL is longer than the distance of the ADM from the nerve, the results suggest that a partial dissection of the anatomical structures might be needed. Direct visualization of the harvesting region might be considered in such cases.

A Patella-Sided Tensioning Technique for Medial Patellofemoral Ligament Reconstruction

Reconstruction of the medial patellofemoral ligament (MPFL) is a common procedure for treatment of recurrent patellofemoral instability. Over the last two decades, multiple surgical techniques for MPFL reconstruction have been described with no clear consensus on a superior reconstruction technique. Appropriate graft tensioning is one of the most important factors for a successful MPFL reconstruction. Overtensioning of the MPFL graft can lead to patellofemoral joint overload and undertensioning can lead to recurrent instability. Current literature demonstrates descriptions of MPFL reconstruction with final graft tensioning performed off of the femoral side. We describe a technique in this article for performing final graft tensioning from the patellar side, which gives the surgeon an option for intraoperative tension adjustments after evaluating patellar tracking.

Medial patellofemoral ligament reconstruction combined with derotational distal femoral osteotomy yields better outcomes than isolated procedures in patellar dislocation with increased femoral anteversion

PURPOSE

The purpose of this study was to evaluate and compare clinical and radiological outcomes between isolated medial patellofemoral ligament reconstruction (MPFLR) and MPFLR combined with derotational distal femoral osteotomy (DDFO) for patellar dislocation with increased femoral anteversion (FA).

METHODS

Between 2014 and 2019, 36 patients who underwent isolated MPFLR and 31 patients who underwent MPFLR combined with DDFO were retrospectively included. Clinical outcomes included physical examinations, functional outcomes (Kujala, Lysholm, International Knee Documentation Committee (IKDC), and Banff Patella Instability Instrument (BPII) scores), activity level (Tegner activity score and return to sports), complications, and patellar re-dislocation rate. Radiological outcomes included patella tilt angle, patellar congruence angle, and patella-trochlear groove distance.

RESULTS

All clinical outcomes improved significantly in both groups, but the DDFO group had significantly better postoperative scores than the MPFLR group (Kujala: 85.1 ± 7.7 vs. 80.5 ± 8.4, P = 0.023; Lysholm: 86.8 ± 8.2 vs. 81.9 ± 9.1, P = 0.026; IKDC: 86.2 ± 10.0 vs. 81.7 ± 8.1, P = 0.045; and BPII: 68.0 ± 12.5 vs. 62.3 ± 10.0, P = 0.039). Both groups achieved successful return to sports (90.3% vs. 91.7%). No re-dislocation or major complications occurred. Radiological outcomes improved significantly in both groups, but the DDFO group had better outcomes (P < 0.05). The tibial tubercle-trochlear groove distance was only improved after DDFO from 17.0 ± 2.3 mm to 15.1 ± 2.0 mm (P = 0.001).

CONCLUSION

Both isolated MPFLR and MPFLR combined with DDFO yielded satisfactory clinical and radiological outcomes in the treatment of patellar dislocation with increased FA. However, combined DDFO had better outcomes and should be considered a priority.

LEVEL OF EVIDENCE

Level III.

Isolated medial patellofemoral ligament reconstruction results in similar postoperative outcomes as medial patellofemoral ligament reconstruction and tibial-tubercle osteotomy: a systematic review and meta-analysis

PURPOSE

To determine the effect of isolated medial patellofemoral ligament reconstruction (MPFLR) versus concomitant MPFLR and tibial-tubercle osteotomy (TTO) on patient-reported functional outcomes, rate of patellar redislocation, and rate of return to sport in skeletally mature patients with recurrent patellar instability and lateralization as defined by elevated tibial-tubercle trochlear groove (TT-TG) distance.

METHODS

Three databases MEDLINE, PubMed and EMBASE were searched from inception to July 10th, 2022 for literature outlining the management of patients with TT-TG indices greater than 15 mm with either isolated MPFLR or concomitant MPFLR and TTO procedures. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on functional outcomes via the Kujala anterior knee pain score, redislocation rates, return to sport rates, and complications were recorded. The MINORS score was used for all studies to perform a quality assessment of included studies.

RESULTS

A total of 31 studies comprising 1405 patients (1452 knees) were included in this review. The mean Kujala score in 13 studies comprising 848 total patients in the isolated MPFLR group was 85.0 (range 80.9-97.5) compared to a score of 83.7 (range 77.2-94.0) in 14 studies comprising 459 patients in the concomitant group. The mean pooled redislocation rate in 19 studies examining isolated MPFLR procedures comprising 948 patients was 3.1% (95% CI 2.1-4.4%, I² = 7%) as opposed to 3.2% (95% CI 1.9-5.0%, I² = 0%) in 15 studies comprising 486 patients in the concomitant group. The mean pooled return to sport rate in seven studies with 472 total patients in the isolated MPFLR group was 82% (95% CI 78-86%, I² = 16%) compared to a score of 92% (95% CI 78-99%, I² = 58%) in four studies comprising 54 patients in the concomitant group. There were similar complication rates between both treatment groups, including range of motion deficits, fractures, infections, and graft failures.

CONCLUSION

Isolated MPFLR leads to similar anterior knee pain, similar redislocation rates and lower return to sport rates than concomitant MPFLR and TTO procedures in patients with TT-TG distances greater than 15 mm. Information from this review can aid surgeons in their decision to choose MPFLR versus concomitant procedures for this patient population, and can also guide future studies on this topic.

LEVEL OF EVIDENCE

Level IV.

Medial patellofemoral ligament is a part of the vastus medialis obliquus and vastus intermedius aponeuroses attaching to the medial epicondyle

PURPOSE

This study aimed to investigate the bony surface characteristic of the femoral attachment of the medial patellofemoral ligament (MPFL) and the correlation between the relevant layered structures, including muscular aponeurosis and the joint capsule, which contribute to patellofemoral joint (PFJ) stability.

METHODS

The morphology of the medial aspect of the medial condyle using micro-computed tomography and analysed cortical bone thickening in 24 knees was observed. For the macroscopic and histological analyses, 21 and 3 knees were allocated, respectively. The Kruskal-Wallis one-way analysis of variance test with Dunn post hoc testing was performed for statistical analysis.

RESULTS

At the level of the adductor tubercle, there were no significant differences in cortical bone thickness. At the level of the medial epicondyle (MEC), cortical bone thickness was considerably greater than that in other areas of the medial condyle (mean ± standard deviation, 0.60 ± 0.20 mm; p < 0.0001). Macroscopic analysis revealed that the deep aponeurosis of the vastus medialis obliquus and the tendinous arch of the vastus intermedius distally formed the composite membrane and adjoined to the joint capsule to firmly attach to MEC, which was located at 41.3 ± 5.7 mm posterior and 14.2 ± 3.1 mm superior to the joint cartilage. Histological analysis showed a composite membrane and adjoining capsule attached to MEC via fibrocartilage.

CONCLUSION

MPFL could be interpreted as part of the deep aponeurosis of the vastus medialis obliquus (VMO) and the tendinous arch of the vastus intermedius, which combined with the joint capsule to attach to MEC. The cortical bone thickening indicated that the tensile stresses were loaded on MEC in aged cadavers. Involvement of VMO and vastus intermedius aponeuroses in restored graft of MPFL could utilise the dynamic stability of surrounding muscles to mimic a native structure.