Results of isolated lateral retinacular reconstruction for iatrogenic medial patellar instability

Lateral Patellofemoral Ligament Reconstruction: A Biomechanical Comparison of 2 Techniques

BACKGROUND

The importance of maintaining lateral patellar stabilizing structures has been demonstrated by the presence of iatrogenic medial patellar instability after lateral retinacular release (LRR) procedures. In patients with medial patellar instability, lateral patellofemoral ligament (LPFL) reconstruction has been clinically shown to restore patellar stability while improving patient-reported outcomes. However, the biomechanics associated with different LPFL reconstruction techniques remain largely unknown.

PURPOSE

To (1) investigate whether LPFL reconstruction restores medial patellar translation compared with the intact state after LRR and (2) evaluate for any biomechanical differences between soft tissue and osseous LPFL reconstruction techniques.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 7 knees were included in the final analysis. The knees were dissected, and the tibia and femur were potted. An eye screw was then placed at the midpoint of the patella perpendicular to the medial surface. A custom jig was constructed to allow for a 1-kg load to be applied to the quadriceps muscle. Medial patellar displacement was investigated at 0°, 10°, 20°, 30°, 45°, 60°, and 90° of knee flexion using a tensile testing machine with a 20-N medial force applied to the patella. Medial patellar displacement was assessed in 4 states: intact, LRR, soft tissue LPFL reconstruction (inserted through incisions in the iliotibial band, quadriceps tendon, and patellar tendon), and osseous LPFL reconstruction.

RESULTS

The LRR group had significantly greater medial patellar translation compared with the intact group throughout flexion (P < .01 to P = .029). The soft tissue LPFL reconstruction group demonstrated significantly greater medial patellar translation at 30° (P = .020) and 45° (P = .025) compared with the intact group, with less translation compared with the LRR group at all degrees of knee flexion except for 45° (P = .065). The osseous LPFL reconstruction group demonstrated significantly greater medial patellar translation compared with the intact group at 30° of flexion (P = .036), with significantly less translation compared with the LRR group from 0° to 30° (P < .01 to P = .013). The soft tissue LPFL reconstruction group (15.94 ± 2.55 mm) demonstrated significantly greater medial patellar translation at 10° of flexion compared with the osseous LPFL reconstruction group (14.16 ± 2.34 mm) (P = .033).

CONCLUSION

Soft tissue LPFL reconstruction led to significantly greater medial patellar translation at 30° and 45° compared with the intact state, while osseous LPFL reconstruction produced significantly greater translation only at 30°. Both the soft tissue and the osseous reconstruction techniques resulted in comparable medial patellar translation at all degrees of knee flexion except for 10°, in which osseous reconstruction was more similar to the intact state.

CLINICAL RELEVANCE

Compared with LRR, soft tissue LPFL reconstruction was able to restore stability against medial patellar translation at most degrees of knee flexion, while osseous LPFL reconstruction did not provide adequate stabilization beyond 30° of flexion. While the LPFL does appear to have osseous insertions, soft tissue reconstruction functioned more similarly to the intact state after LRR.

Trends in Lateral Retinacular Release from 2010 to 2017

Historically, lateral retinacular release (LRR) procedures have been utilized in the treatment of a variety of patellofemoral disorders, including lateral patellar instability. However, in the past decade, there has been an increasing awareness of the importance of the lateral stabilizers in patellar stability, as well as the complications of LRR, such as recurrent medial patellar instability. The purpose of this study was to investigate current trends in LRR procedures from 2010 through 2017 using a large national database. The American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for arthroscopic LRR procedures (the Current Procedural Terminology [CPT] code, 29873) from 2010 to 2017. The number and incidence of lateral release procedures, both isolated and nonisolated, were analyzed and separated into cohorts for analysis. Age and gender of the LRR cohort was investigated and compared with all other orthopaedic procedures during the same time period in the NSQIP database. In addition, concomitant procedures and associated International Classification of Disease-9th Revision (ICD-9) and ICD-10th Revision (ICD-10) codes were analyzed over time and between LRR groups. From 2010 to 2017, 3,117 arthroscopic LRRs were performed. The incidence for LRR was 481.9 per 100,000 orthopaedic surgeries in 2010 and significantly decreased to 186.9 per 100,000 orthopaedic surgeries in 2017 (p < 0.01). LRR was more commonly performed in females (66%) and 58% of patients were under 44 years of age. In addition, LRR was most commonly performed with a concomitant meniscectomy (36%), synovectomy (19%), or microfracture (13%), and for a diagnosis of pain (22%). The overall incidence of LRR procedures significantly decreased from 2010 to 2017. LRRs were more commonly performed in younger, female patients for a diagnosis of pain with the most common concomitant procedure being meniscectomy, synovectomy, or microfracture.

Kinesiophobia, Knee Self-Efficacy, and Fear Avoidance Beliefs in People with ACL Injury: A Systematic Review and Meta-Analysis

BACKGROUND

To improve the understanding of the psychological impacts of anterior cruciate ligament (ACL) injury, a systematic review synthesizing the evidence on knee self-efficacy, fear avoidance beliefs and kinesiophobia following ACL injury is needed.

OBJECTIVE

The aim of this systematic review was to investigate knee self-efficacy, fear avoidance beliefs and kinesiophobia following ACL injury, and compare these outcomes following management with rehabilitation alone, early and delayed ACL reconstruction (ACLR).

METHODS

Seven databases were searched from inception to April 14, 2022. Articles were included if they assessed Tampa Scale of Kinesiophobia (TSK), Knee Self-Efficacy Scale (KSES), or Fear Avoidance Beliefs Questionnaire (FABQ). Risk of bias (RoB) was assessed using domain-based RoB tools (ROBINS-1, RoB 2, RoBANS), and GRADE-assessed certainty of evidence. Random-effects meta-analyses pooled outcomes, stratified by time post-injury (pre-operative, 3-6 months, 7-12 months, > 1-2 years, > 2-5 years, > 5 years).

RESULTS

Seventy-three studies (70% high RoB) were included (study outcomes: TSK: 55; KSES: 22; FABQ: 5). Meta-analysis demonstrated worse kinesiophobia and self-efficacy pre-operatively (pooled mean [95% CI], TSK-11: 23.8 [22.2-25.3]; KSES: 5.0 [4.4-5.5]) compared with 3-6 months following ACLR (TSK-11: 19.6 [18.7-20.6]; KSES: 19.6 [18.6-20.6]). Meta-analysis suggests similar kinesiophobia > 3-6 months following early ACLR (19.8 [4.9]) versus delayed ACLR (17.2 [5.0]). Only one study assessed outcomes comparing ACLR with rehabilitation only.

CONCLUSIONS

Knee self-efficacy and kinesiophobia improved from pre-ACLR to 3-6 months following ACLR, with similar outcomes after 6 months. Since the overall evidence was weak, there is a need for high-quality observational and intervention studies focusing on psychological outcomes following ACL injury.

A Comprehensive Description of the Lateral Patellofemoral Complex: Anatomy and Anisometry

BACKGROUND

The lateral patellofemoral complex (LPFC) is an important stabilizer of the patella composed of the lateral retinacular structures including the lateral patellofemoral ligament (LPFL), the lateral patellomeniscal ligament (LPML), and the lateral patellotibial ligament (LPTL). While the isolated anatomy of the LPFL has been previously described, no previous study has investigated the entirety of the LPFC structure, length changes, and radiographic landmarks. An understanding of LPFC anatomy is important in the setting of LPFL injury or previous lateral release resulting in iatrogenic medial instability requiring LPFC reconstruction.

PURPOSE

To both qualitatively and quantitatively describe the anatomy and length changes of the LPFC on gross anatomic dissections and standard radiographic views.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired cadaveric specimens were utilized in this study. Specimens were dissected to identify distinct attachments of the LPFL, LPML, and LPTL. Ligament lengths, footprints, and centers of each attachment were described with respect to osseous landmarks using a 3-dimensional coordinate measuring device. Ligament length changes were also assessed from 0° to 90° of flexion. Radiopaque markers were subsequently utilized to describe attachments on standard anteroposterior and lateral radiographic views.

RESULTS

The individual elements of the LPFC were identified in all specimens. The LPFL patellar attachment had an average total length of 22.5 mm (range, 18.3-27.5 mm), involving a mean of 59% (range, 50%-75%) of the sagittal patella. Based on the average patellar size, a mean of 63% of the LPFL attached to the patella, and the remainder (11.1 ± 1.4 mm) inserted into the patellar tendon. The femoral attachment of the LPFL had a mean maximum length of 24.4 ± 4.3 mm. The center of the LPFL femoral attachment was a mean distance of 13.5 ± 3.2 mm anterior and distal to the lateral epicondyle. The LPFL demonstrated significant shortening, especially in the first 45° of flexion (7.5 ± 5.1 mm). In contrast, the LPTL (5.5 ± 3.0 mm) and LPML (10.0 ± 3.3 mm) demonstrated significant shortening from 45° to 90°. On lateral radiographs, the center of the femoral attachment of the LPFL was a mean total distance of 19.2 ± 7.2 mm from the lateral epicondyle.

CONCLUSION

The most important findings of this study were the correlative anatomy of 3 distinct lateral patellar ligaments (LPFL, LPML, and LPTL) and their anisometry through flexion. All 3 components demonstrated significant shortening during flexion. The quantitative and radiographic measurements detailed the LPFL osseous attachment on the patella; soft tissue attachment on the patellar tendon; and finally, the osseous insertion on the femur distal and anterior to the lateral epicondyle. Similarly, the authors documented the meniscal insertion of the LPML and defined a patellar insertion of the LPTL and LPML as a single attachment. These data allow for reproducible landmarks to aid in the understanding and reconstruction of the lateral patellar restraints.

CLINICAL RELEVANCE

The data produced from this investigation provide a comprehensive description of these 3 lateral patellar stabilizers (LPFL, LPML, LPTL). These data can be used intraoperatively to facilitate anatomic reconstructions of the lateral patellar stabilizers.

Medial Patellofemoral Ligament Reconstruction With Concomitant Lateral Patellofemoral Reconstruction for Patellar Instability

Patients with bidirectional patellar instability who are unresponsive to conservative management may benefit from a medial patellofemoral ligament (MPFL) reconstruction and lateral patellofemoral ligament (LPFL) reconstruction. If an isolated MPFL reconstruction does not provide adequate stabilization intraoperatively, combined MPFL and LPFL reconstruction allows independent reconstruction, which can be performed with a facile, reproducible technique. The purpose of this report was to describe our technique for performing an MPFL reconstruction with a concurrent soft-tissue LPFL reconstruction combined with a distalizing tibial tubercle osteotomy to correct patella alta.

Surgical Technique for Obligate Flexion Patellar Dislocation: Medial Patellofemoral Ligament Reconstruction, Distal Femoral Osteotomy, Quadricepsplasty, and Lateral Retinacular Reconstruction with Dermal Allograft

Lateral patellar dislocation is a relatively common pathology that can be surgically treated with a medial patellofemoral ligament reconstruction. In rare occurrences patients can present with patellar maltracking that results in obligate patellar instability in flexion but central tracking in extension. This presentation can be much more complicated to treat surgically and may require a combination of multiple patellofemoral procedures. In this technique we describe a four-pronged treatment approach for improving patellar tracking in a patient with obligate flexion patellar dislocation and valgus malalignment including VY quadricepsplasty, distal femoral osteotomy, medial patellofemoral ligament reconstruction, and lateral retinacular and capsular reconstruction with a dermal allograft.

Noniatrogenic Medial Patellar Dislocations: Case Series and International Patellofemoral Study Group Experience

Background:

Most patellar dislocations occur in a lateral direction because of a summed lateral force vector and predisposing anatomic risk factors. Medial patellar instability is rare and is a well-recognized iatrogenic complication of an overly aggressive lateral retinacular release. Noniatrogenic medial patellar dislocations are rare. The management of these injuries is not well described.

Purpose:

To describe the experience of the International Patellofemoral Study Group with patients with noniatrogenic medial patellar dislocation.

Study Design:

Case series; Level of evidence, 4.

Methods:

Members of the International Patellofemoral Study Group (N = 64) were surveyed between October 2018 and April 2019. This group was chosen because of its wide referral base and interest in patellar instability. Specialists who had encountered a patient with medial patellar instability were sent a questionnaire inquiring about details of the case, including patient demographics, medical history, level of athletic competition, injury characteristics, and treatment. Cases were confirmed by physical examination records and, in some cases, with findings on advanced radiographic imaging.

Results:

The survey response rate was 73% (47/64). Three of the 47 specialists (6.4%) reported they had seen a case of noniatrogenic medial patellar dislocation, for a total of 6 cases. Four cases were described as recurrent medial dislocations in the setting of hypermobile Ehlers-Danlos syndrome; 2 were treated nonoperatively, 1 underwent lateral patellofemoral ligament reconstruction, and 1 underwent derotational osteotomies. Two medial-sided patellar dislocations in collegiate athletes were sports-related injuries that required surgical debridement but no ligamentous reconstruction. None of the patients had persistent or recurrent instability at the time of their most recent follow-up.

Conclusion:

Noniatrogenic medial patellar dislocations are extremely rare. This case review suggests that the treatment of first-time medial patellar instability in patients without known risk factors should follow the same principles as the treatment of lateral instability with no known risk factors, which is nonoperative management. For patients with documented risk factors and recurrence, surgery to address the risk factors may be appropriate.

Concomitant Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Osteotomy Do Not Increase the Incidence of 30-Day Complications: An Analysis of the NSQIP Database

Background:

Lateral patellar dislocations account for 2% to 3% of total knee injuries, especially in adolescents. Depending on the anatomic abnormality contributing to lateral patellar instability, medial patellofemoral ligament reconstruction (MPFLR) and/or tibial tubercle osteotomy (TTO) may be indicated.

Purpose:

To assess the risk of adverse events (AEs) after TTO, MPFLR, and concomitant MPFLR and TTO.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients who underwent MPFLR, TTO, and concomitant MPFLR and TTO between 2005 and 2016 were identified through the American College of Surgeons–National Surgical Quality Improvement Program (ACS-NSQIP) database. Medical complications (eg, surgical site infection and deep vein thrombosis), readmission rates, and extended hospital stay within 30 days of the procedure were recorded. Outcomes were compared with bivariate and multivariate Poisson regression.

Results:

Out of 882 patients, 617 (70.0%) underwent isolated MPFLR, 170 (19.3%) underwent TTO, and 95 (10.8%) underwent concomitant MPFLR and TTO. The operative time for concomitant MPFLR and TTO was significantly longer (122 ± 45 minutes) compared with isolated MPFLR (97 ± 55 minutes; P < .001) and isolated TTO (89 ± 51 minutes; P < .001). There were 32 AEs (3.6%), with 10 AEs in the isolated TTO group (5.9%), 18 AEs in the isolated MPFLR group (2.9%), and 4 AEs in the MPFLR + TTO group (4.2%). There was no significant difference in the rate of AEs between the isolated MPFLR and isolated TTO groups (P = .1), isolated MPFLR and MPFLR + TTO groups (P = .5), and isolated TTO and MPFLR + TTO groups (P = .8). Diabetes mellitus was associated with an increased risk of developing an AE (odds ratio, 4.0; P = .003), and hypertension resulted in an increased risk of an extended hospital stay (odds ratio, 4.0; P = .010).

Conclusion:

While concomitant MPFLR and TTO significantly increased operative time, there was no difference in the rate of AEs, extended hospital stay, and readmissions within 30 days after isolated MPFLR, isolated TTO, and concomitant MPFLR and TTO.

Patellar Instability Management: A Survey of the International Patellofemoral Study Group

BACKGROUND

Although patellofemoral instability is among the most prevalent knee disorders, the management of patients with this condition is complex and remains variable, given the lack of long-term, high-level clinical outcome studies to compare various operative and nonoperative modalities.

PURPOSE

To discover a consensus within treatment controversies in patellofemoral instability among experienced knee surgeons with a specific interest in the patellofemoral joint.

STUDY DESIGN

Expert opinion; Level of evidence, 5.

METHODS

A 3-step modified Delphi technique was used to establish a consensus. A 34-question, case-based online survey regarding patellofemoral instability was distributed to all active members of the International Patellofemoral Study Group. Consensus statements were generated if at least 66% of the respondents agreed and then redistributed to the same panel. Modifications to the consensus statements were made based on the iterative feedback process until no discordance was encountered in the third stage.

RESULTS

Eight consensus statements were achieved. Nonoperative management is the current standard of care for a first-time dislocation in the absence of an osteochondral fragment or loose body requiring excision (100% agreement). In patients with a first-time dislocation with an operative osteochondral fracture requiring excision or repair, patellar instability should be addressed concurrently (89% agreement). Recurrent instability should be treated surgically, with most surgeons favoring medial reconstruction (77%-86% agreement). While there is general agreement that bony procedures should be performed to correct underlying bony deformities, there is no consensus regarding the most appropriate type of procedure performed. Lateral release should not be performed in isolation for the treatment of patellar instability (89% agreement).

CONCLUSION

Despite the consensus generated in this study, our current understanding remains limited by a lack of high-level evidence as well as the numerous complex variables influencing treatment decision making. High-quality, multicenter randomized controlled trials, particularly those directly comparing specific surgical treatment methods while controlling for underlying risk factors, are needed to address these areas of uncertainty.

Medial Patellar Instability: A Systematic Review of the Literature of Outcomes After Surgical Treatment

PURPOSE

To perform a systematic review of literature reporting on outcomes after surgical treatment of medial patellar instability.

METHODS

A systematic review was performed according to PRISMA guidelines. Inclusion criteria were as follows: the outcomes and complications of medial patellar instability repair with a follow-up greater than 12 months, English language, and human studies. We excluded cadaveric studies, animal studies, basic science articles, editorial articles, review articles, and surveys.

RESULTS

Searches identified 1,116 individual titles. After inclusion and exclusion criteria were applied, a total of 8 studies were identified. Three studies exclusively included patients with previous lateral release; 1 included patients with chronic instability; 1 included patients with both previous lateral release and other surgical causes; 1 study had patients with previous lateral release, spontaneous instability, and instability due to injury; 1 study included patients after tibial tubercle transfer surgery; and 1 study did not report the etiology of instability.

CONCLUSIONS

Good to excellent outcomes were reported postoperatively in 85% of the patients after surgical treatment of medial patellar instability. However, clinical outcomes data for medial patellar ligament reconstruction is sparse and highly heterogeneous. There is inconsistency in the literature in regard to the indication, timing, and procedure.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Why Do Patellofemoral Stabilization Procedures Fail? Keys to Success

In recent years, surgical interventions for patellofemoral joint instability have gained popularity, possibly revitalized by the recent advances in our understanding of patellofemoral joint instability and the introduction of a number of new surgical procedures. This rise in surgical intervention has brought about various complications. In this review article, we present the complications that are associated with 5 main surgical procedures to stabilize the patella-medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, trochleoplasty, lateral release/lateral retinacular lengthening, and derotation osteotomies. The key to success and potential problems with these surgical techniques are highlighted in the form of "expert takeaways."

Medial Patellar Instability: Treatment and Outcomes

Background:

Historically, a lateral retinacular release was one of the primary surgical interventions used to treat lateral patellar instability. However, disruption of the lateral structures during this procedure has been associated with medial instability of the patella.

Hypothesis:

We hypothesize that good to excellent outcomes can be achieved at midterm follow-up after lateral patellotibial ligament reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

Thirteen patients were treated for medial patellar instability with a lateral patellotibial ligament reconstruction between May 2011 and December 2013 by a single surgeon. All patients had previously undergone a lateral release procedure and had symptomatic medial patellar instability. Patients were evaluated using patient-reported outcome scores at a minimum of 2 years postsurgery.

Results:

The mean Lysholm score improved from 45.6 (range, 11-76) to 71.9 (range, 30-91). The median preoperative Tegner activity scale score was 3 (range, 1-7), while the median postoperative score was 4 (range, 1-9). The median Western Ontario and McMaster Universities Arthritis Index (WOMAC) total score improved from 38 (range, 1-57) preoperatively to 6 postoperatively (range, 0-52). The mean patient satisfaction postoperatively was 8.2 (range, 5-10).

Conclusion:

Significantly improved outcomes can be achieved at midterm follow-up with a low rate of complications when reconstructing the lateral patellotibial ligament in the setting of iatrogenic medial patellar instability.

Failed medial patellofemoral ligament reconstruction: Causes and surgical strategies

Patellar instability is a common clinical problem encountered by orthopedic surgeons specializing in the knee. For patients with chronic lateral patellar instability, the standard surgical approach is to stabilize the patella through a medial patellofemoral ligament (MPFL) reconstruction. Foreseeably, an increasing number of revision surgeries of the reconstructed MPFL will be seen in upcoming years. In this paper, the causes of failed MPFL reconstruction are analyzed: (1) incorrect surgical indication or inappropriate surgical technique/patient selection; (2) a technical error; and (3) an incorrect assessment of the concomitant risk factors for instability. An understanding of the anatomy and biomechanics of the MPFL and cautiousness with the imaging techniques while favoring clinical over radiological findings and the use of common sense to determine the adequate surgical technique for each particular case, are critical to minimizing MPFL surgery failure. Additionally, our approach to dealing with failure after primary MPFL reconstruction is also presented.

Clinical results after treatment for bidirectional patellar subluxation: Minimum 2-years follow-up

BACKGROUND

We describe the preliminary clinical results of a patellar stabilization technique to treat bidirectional patellar subluxation (BPS).

METHODS

Patients: six patients (one male, five females; mean age 30.2years) underwent this procedure with a minimum of 24months follow-up. Patients were assessed for clinical instability, patellar complications, and need for revision surgery. Patient functional outcomes were evaluated using the criteria of Crosby and Insall and the Kujala Anterior Knee Pain Scale at the time of final follow-up. Patient satisfaction was assessed using a subjective questionnaire.

OPERATIVE TECHNIQUE

A semitendinosus tendon autograft is coursed through a transverse tunnel in the distal quadriceps tendon. The medial and lateral aspects of the graft are passed from the quadriceps tendon within subfascial tunnels to the MPFL attachment site and lateral epicondyle, respectively. The graft is fixed in 60° of knee flexion with suture anchors.

RESULTS

Surgery for recurrent instability was performed in one case. There were no cases of infection, quadriceps tendon rupture, or patella fracture. At average follow-up of 29.2months (range, 24 to 38months), outcomes were good to excellent in 4/6 of cases. Kujala scores improved significantly from 33.3 (range, three to 58) preoperatively to 70.8 (range, 39 to 96) postoperatively (p<0.05). 5/6 patients reported being satisfied to completely satisfied with their result.

CONCLUSION

Patients undergoing bidirectional patellar stabilization with a single tendon graft showed improved postoperative functional scores. The technique is successful in reducing pain and restoring bidirectional patellar stability at 2-years follow-up.

LEVEL OF EVIDENCE

IV, retrospective case series.

How to Deal With Anterior Knee Pain in the Active Young Patient

Context:

Anterior knee pain (AKP) represents the most common reason to consult with a clinician who specializes in the knee. Despite the high incidence of the disorder, however, its etiology is still controversial. Many unnecessary surgeries that may damage the patient are done for this clinical entity.

Evidence Acquisition:

A PubMed search from 1995 through June 2016.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

The etiology of AKP is multifactorial, and patients with AKP may therefore be divided into several subpopulations. The whole picture must be addressed for each patient to identify all potentially modifiable factors and to achieve better outcomes. Both pelvifemoral dysfunction and psychological factors that may affect the development and symptoms of AKP must be considered to identify therapeutic targets within the context of treatment. Patients presenting with AKP frequently respond well to load restriction that protects their knee and reduces pain during rehabilitation. Surgery should only be considered in very select cases. In a patient who has undergone previous patellar realignment surgery and experienced increased pain, iatrogenic medial patellar instability should be considered.

Conclusions:

The etiology of AKP is multifactorial, and several subpopulations of AKP patients exist and their treatment must be personalized. Normally, the focus is on the knee of a patient with AKP, and only that joint is examined. However, that focus can lead to overlooking other important etiological factors that may be present.

Iatrogenic medial patellar instability following lateral retinacular release of the knee joint

PURPOSE

Iatrogenic medial patellar instability (IMPI) is a disabling but easily missed condition that is most often seen as a late complication of lateral retinacular release (LRR) procedures. The purposes of this study were (1) to summarize the available diagnostic methods and (2) to explore the contributing factors of IMPI following LRR procedures.

METHODS

The MEDLINE, PubMed, EMBASE and Cochrane Library databases were searched for studies including diagnosed IMPI cases following LRR procedures. All patients were first divided into IMPI group and non-IMPI group based on the diagnostic methods of IMPI collected from studies. Univariate analysis was performed by comparing the two groups with regard to individual patient data (age at initial LRR, gender) and surgical details (type, releasing scope, combined surgeries and indication) of LRR procedures. Multivariate logistic regression was carried out to identify independent contributing factors for IMPI and to calculate odds ratios (ORs).

RESULTS

Eight studies with 274 patients (300 knees) were finally included. Of those, 161 patients (171 knees, 57.0 %) had IMPI and 113 patients (129 knees, 43.0 %) had no IMPI. Univariate analysis revealed a statistically significant difference between both groups for releasing scope (P 1 < 0.001) and indication of LRR procedures (P 2 < 0.001), with releasing lateral retinaculum (LR) + vastus lateralis (VL) tendon and absence of tight LR during the initial LRR procedures being more common in patients with IMPI. The independent contributing factors for IMPI identified in the multivariate logistic regression analysis were releasing LR + VL (OR1 = 16.49) and absence of tight LR (OR2 = 14.37).

CONCLUSIONS

The IMPI was more common in patient with an over-released LRR and patient who was absent of tight LR during the initial LRR procedures. Aggressive surgical corrections and inappropriate indications of initial LRR were two contributing factors for the late complications of IMPI. This study suggests that the IMPI may occur as a major complication of LRR, especially when the VL tendon is extensively released or when there is no confirmative clinical evidence of a tight LR preoperatively.

LEVEL OF EVIDENCE

IV.

Lateral patellofemoral ligament reconstruction to restore functional capacity in patients previously undergoing lateral retinacular release

AIM: To study patient outcomes after surgical correction for iatrogenic patellar instability.

METHODS: This retrospective study looked at 17 patients (19 knees) suffering from disabling medial patellar instability following lateral release surgery. All patients underwent lateral patellofemoral ligament (LPFL) reconstruction by a single surgeon. Assessments in all 19 cases included functional outcome scores, range of motion, and assessment for the presence of apprehension sign of the patella to determine if LPFL reconstruction surgery was successful at restoring patellofemoral stability.

RESULTS: No patients reported any residual postoperative symptoms of patellar instability. Also no patients demonstrated medial patellar apprehension or examiner induced subluxation with the medial instability test described earlier following LPFL reconstruction. Furthermore, all patients recovered normal range of motion compared to the contralateral limb. For patients with pre and postoperative outcome scores, the mean overall knee injury and osteoarthritis outcome score increased significantly, from 34.39 preoperatively (range: 7.7-70.12) to 69.54 postoperatively (range: 26.82-91.46) at final follow-up (P < 0.0001).

CONCLUSION: This novel technique for LPFL reconstruction is effective at restoring lateral restraint of the patellofemoral joint and improving joint functionality.

Coronal patellar osteotomy of the external facet combined with the release of the lateral retinaculum improves the clinical outcomes of isolated lateral release in lateral knee compartment syndrome

OBJECTIVE

To describe a novel coronal osteotomy of the external facet of the patella, and to evaluate if the outcomes of the treatment of lateral knee compartment syndrome (LKCS) with this osteotomy, combined with the release of the external lateral retinaculum, are better than the isolated lateral retinacular release.

MATERIAL AND METHODS

A prospective study with a 2 year follow up that included 70 patients diagnosed with LKCS, distributed into 2 groups. The first group included 50 patients on whom the lateral retinacular release combined with osteotomy was performed, and a second group on whom an isolated retinacular release was performed. Measurements were made using the Werner functional scale before the surgery and at 3, 12, and 24 months follow-up.

RESULTS

There were significant differences in the overall functional state between the two groups after the surgery (better in the osteotomy group at all the intervals, P<.05). The improvement, which was progressive up to 12 months, was slightly less at 24 months, although the values were still better than the pre-surgical ones in both groups. Pain was the variable that showed most improvement. The patients with LKCS with degenerative signs showed a benefit in all cases.

CONCLUSION

The results demonstrate that the described patellar osteotomy technique, combined with lateral retinacular release, significantly improves the pain and the functional scale score of patients with LKCS after 2 years of follow-up, to a greater extent than isolated lateral retinacular release, including those in which there was evidence of degenerative signs.

How to Deal With Chronic Patellar Instability: What Does the Literature Tell Us?

CONTEXT

Patellar instability is a common clinical problem, affecting between 7 and 49 people per 100,000. However, not all patellar instabilities are equal, the etiology of the disorder is multifactorial, and a clear understanding of the cause of instability is crucial for appropriate surgical treatment. The goal of this article is to identify how to best treat patellar instability to provide good outcomes and hopefully prevent future osteoarthritis.

EVIDENCE ACQUISITION

A PubMed search from 1983 through May 2015.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Several subpopulations of patients with chronic patellar instability exist: (1) lateral patellar instability during the early arc of knee flexion (0°-30°), (2) lateral patellar instability persisting beyond 30° of knee flexion, (3) lateral patellar instability in greater knee flexion, and (4) medial patellar instability. In patients with lateral instability during the early arc of knee flexion, the medial patellofemoral deficiency is the essential lesion. Persistent instability beyond 30° of knee flexion suggests an unusually high patella, severe trochlear dysplasia, pathologic increment of the tibial tuberosity-trochlear groove distance, or a combination of these factors. In patients with lateral instability in greater knee flexion, increasing and unbalanced tension in the extensors pulls the patella out of the groove as the knee is flexed. Finally, medial patellar instability is an objective iatrogenic condition that appears after realignment surgery in the vast majority of cases.

CONCLUSION

The etiology of chronic patellar instability is multifactorial, and its treatment must therefore be personalized.

STRENGTH OF RECOMMENDATION TAXONOMY SORT

B.

Iatrogenic Medial Patellar Instability: An Avoidable Injury

Iatrogenic medial patellar instability is a specific condition that frequently causes incapacitating anterior knee pain, severe disability, and serious psychological problems. The diagnosis should be suspected in a patient who has undergone previous patellar realignment surgery that has made the pain worse. The diagnosis can be established by physical examination and simple therapeutic tests (e.g., "reverse" McConnell taping) and confirmed by imaging techniques. This iatrogenic condition should no longer exist and could almost be eliminated by avoiding over-release of the lateral retinaculum.

Deep Transverse Lateral Retinaculum Reconstruction for Medial Patellar Instability

Medial patellar instability can be a disabling complication of an extensive lateral retinaculum release. It is often overlooked, and for the diagnosis, it is necessary to have a high index of suspicion. Typically, the patient feels a new pain and new instability after the lateral retinaculum release that are distinct from, and much worse than, those before surgery. All of our patients had significant relief from their pain with "reverse" McConnell taping. If there is a significant improvement in symptoms after this taping and stress radiographs or stress axial computed tomography scans show an objective pathologic medial patellar displacement, reconstruction of the lateral retinaculum should be considered. This article details our technique for reconstruction of the deep transverse layer of the lateral retinaculum using an anterior strip of the iliotibial band. This strip is detached from its insertion onto the Gerdy tubercle and then reflected proximally beyond the level of the lateral femoral epicondyle. Finally, it is attached either by direct suture to the remaining prepatellar and peripatellar retinaculum if there is adequate tissue present or by a suture anchor.