Iatrogenic Medial Patellar Instability: An Avoidable Injury

Evaluation of the relationship between the bone alignment of the lower extremity and the importance of Q angle in male athletes

INTRODUCTION

Evaluating the mechanical-anatomical alignment and angles of the knee joint is crucial for athletes. We aimed to analyse the relationship between lower extremity bone alignment and the importance of the Q angle (QA) in male athletes.

METHODS

We included 38 male professional football athletes without any alignment or varus-valgus deformity who actively played football in various football clubs in Istanbul. This study was conducted using quantitative research methods within the scope of a cohort study design and employed a correlational survey method. A health specialist at the orthopaedic outpatient clinic of the Haseki Training and Research Hospital, Istanbul, evaluated the participants' lower extremity bone alignment using standing anteroposterior radiographs and assessed the QA using the goniometric measurement method. The anatomical lateral distal femoral angle (aLDFA), medial proximal tibial angle (MPTA) and QA data were analysed to assess lower extremity straightness.

RESULTS

Significant relationships between the right and left leg aLDFA, MPTA and QA values of the participants' lower extremity mechanical axis values and between the aLDFA and right leg QA values (r = 0.380, p = 0.019) were found. These relationships were attributed to the difference between proximal and distal alignments of the lower extremities. The correlation between QA and certain mechanical alignment parameters was due to unilateral and bilateral symmetrical arrangements of the lower extremities.

CONCLUSIONS

The parameters of lower extremity mechanical-anatomical alignment are considered preliminary indicators of relationships among sports injuries, structural factors and predisposition to such injuries. Individual differences in the angular values of mechanical-anatomical alignment and the application of different methods for determining these angles have revealed some uncertainties. We determined the mechanical axis data of football athletes who predominantly used their lower extremities using the most reliable methods and examined the relationship among the right and left leg aLDFA, MPTA and QA values. We believe that our findings provide insights and guidance for experts in the field.

Medial Patellar Instability Following Total Knee Arthroplasty

Although lateral patellar instability has been discussed as a complication following total knee arthroplasty (TKA), there are no published reports of medial patellar instability. We present a case of a 72-year-old female patient with a remote history of medializing tibial tubercle osteotomy who underwent TKA complicated by a medial dislocation of the patella. Management consisted of lateral retinaculum imbrication, revision of the patellar component, and lateralizing tibial tubercle osteotomy in the setting of appropriate rotation of the tibial and femoral components. It is important to be aware of medial patellar instability as well as potential treatment options as this is a rare complication that can occur following TKA.

Bilateral Patellofemoral Ligament Reconstruction for Patellar Instability in Ehlers-Danlos Syndrome: A Case Report

CASE

We report the case of an 11-year-old boy with Ehlers-Danlos syndrome (EDC) who exhibited simultaneous medial and lateral patellar instability. The patient presented with a medial patellar dislocation, and subsequently, the patella became very unstable both medially and laterally. Despite distal realignment, the patellar instability was so significant that he underwent simultaneous reconstruction of the medial and lateral patellofemoral ligament using the semitendinosus tendon, with a good result.

CONCLUSION

Simultaneous reconstruction of the medial and lateral patellofemoral ligament is an effective method in cases of extreme patellar instability, such as the EDS case.

Lateral Patellar Instability

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Patellar instability represents a common problem with an evolving understanding and multifactorial pathoetiology. Treatment plans should be based on the identification of contributing anatomical factors and tailored to each individual patient.

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Risks for recurrent instability are dependent on several patient-specific factors including patella alta, increased tibial tubercle-to-trochlear groove (TT-TG) distance, trochlear dysplasia, younger skeletal age, and ligamentous laxity.

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Cartilage or osteochondral lesions and/or fractures are commonly observed in first-time patellar dislocation, and magnetic resonance imaging (MRI) should be strongly considered. Advanced imaging modalities, such as computed tomography (CT) or MRI, should also be obtained preoperatively to identify predisposing factors and guide surgical treatment.

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Medial patellofemoral ligament (MPFL) reconstruction with anatomical femoral tunnel positioning is associated with lower recurrence rates compared with MPFL repair and has become a common and successful reconstructive surgical option in cases of instability.

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Lateral retinacular tightness can be addressed with lateral retinacular release or lengthening, but these procedures should not be performed in isolation.

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Tibial tubercle osteotomy is a powerful reconstructive tool in the setting of underlying skeletal risk factors for instability and can be of particular benefit in the presence of increased TT-TG distance (>20 mm), and/or in the setting of patella alta.

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The indications for trochleoplasty are still developing along with the clinical evidence, but trochleoplasty may be indicated in some cases of severe trochlear dysplasia. Several surgical techniques have indications in specific clinical scenarios and populations, and indications, risks, and benefits to each are progressing with our understanding.

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Combined femoral derotational osteotomy and MPFL reconstruction can be considered for patients with a femoral anteversion angle of >30° to improve patient outcomes and reduce recurrence rates.

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.

Influence of Articular Geometry and Tibial Tubercle Location on Patellofemoral Kinematics and Contact Mechanics

Trochlear groove geometry and the location of the tibial tubercle, where the patellar tendon inserts, have both been associated with patellofemoral instability and can be modified surgically. Although their effects on patellofemoral biomechanics have been investigated individually, the interaction between the two is unclear. The authors' aim was to use statistical shape modeling and musculoskeletal simulation to examine the effect of patellofemoral geometry on the relationship between tibial tubercle location and patellofemoral function. A statistical shape model was used to generate new knee geometries with trochlear grooves ranging from shallow to deep. A Monte Carlo approach was used to create 750 knee models by randomly selecting a geometry and randomly translating the tibial tubercle medially/laterally and anteriorly. Each knee model was incorporated into a musculoskeletal model, and an overground walking trial was simulated. Knees with shallow trochlear geometry were more sensitive to tubercle medialization with greater changes in lateral patella position (-3.0 mm/cm medialization shallow vs -0.6 mm/cm deep) and cartilage contact pressure (-0.51 MPa/cm medialization shallow vs 0.04 MPa/cm deep). However, knees with deep trochlear geometry experienced greater increases in medial cartilage contact pressure with medialization. This modeling framework has the potential to aid in surgical decision making.

A reliable Q angle measurement using a standardized protocol

BACKGROUND

Studies have shown that Q angle measurements were unreliable. Imaging studies have largely replaced the Q angle for measuring tibial tubercle lateralization. Creating a standardized protocol to measure the Q angle, with normative values, would provide a reliable reference without expensive imaging techniques.

METHODS

Thirty men and 27 women without history of knee problems or family history of dislocating kneecaps were subjects. Exclusion criteria were: patellofemoral abnormalities upon examination. We measured the Q angles of both knees using a standardized protocol and a long-armed goniometer. These data were analyzed to calculate normative values.

RESULTS

For all subjects, the mean was 14.8° (≈15°), 95% confidence interval (CI): ±5.4°. The male mean was 13.5°, 95% CI: ±5.2°. The female mean was 15.9°, 95% CI: ±4.8°. There was no significant difference between the right and left knees of the males (p = 0.52), nor of the females (p = 0.62), Beta = 0.14. The 2.4° difference between male and female means was due to the average height difference between the men and women.

CONCLUSIONS

This study provides a standardized Q angle measurement protocol to assess tibial tubercle lateralization at a patient's first encounter (and intra-operatively) without resorting to expensive imaging studies. These values provide a reliable reference for clinical comparison, and will allow all clinicians and sports medicine personnel to assess tubercle lateralization with reliability and validity. When using this protocol, the term "Standard Q Angle" (SQA) should be used, to avoid confusion with other measurement protocols.

Recurrent Patellofemoral Instability in the Pediatric Patient: Management and Pitfalls

PURPOSE OF REVIEW

The purpose of the review is to discuss the relevant pathoanatomy, management, complications, and technical considerations for recurrent patellofemoral instability (PFI) in the pediatric population. Special consideration is given to recent literature and management of the patient with repeat instability following surgery.

RECENT FINDINGS

Patellar stabilization surgery is in principle dependent upon restoration of normal patellofemoral anatomy and dynamic alignment. Historically, treatment options have been numerous and include extensor mechanism realignment, trochleoplasty, and more recently repair and/or reconstruction of the medial patellofemoral ligament (MPFL) as a dynamic check rein during initial knee flexion. In skeletally immature patients, preference is given to physeal-sparing soft tissue procedures. While medial patellofemoral ligament reconstruction has become a popular option, postoperative failure is a persistent issue with rates ranging from 5 to 30% for PFI surgery in general without any single procedure (e.g., distal realignment, MPFL reconstruction) demonstrating clear superiority. Failure of surgical patellar stabilization is broadly believed to occur for three main reasons: (1) technical failure of the primary stabilization method, (2) unaddressed static and dynamic pathoanatomy during the primary stabilization, and (3) intrinsic risk factors (e.g., collagen disorders, ligamentous laxity). PFI is a common orthopedic condition affecting the pediatric and adolescent population. Treatment of repeat instability following surgery in the PFI patient requires understanding and addressing underlying pathoanatomic risk factors as well as risks and reasons for failure.

[Patellofemoral instability in children and adolescents]

Dislocation of the patella is one of the most common knee injuries in childhood and adolescence. After detailed clinical and radiological clarification, conservative functional treatment with special orthotic devices is most commonly applied in patients with a primary dislocation without concomitant injuries; however, the redislocation rate after conservative treatment has been reported in the literature to be between 35% and 70%, depending on the risk factors present. Therefore, numerous surgical treatment options exist which are sometimes again associated with high redislocation rates and others can lead to early arthrosis of the patellofemoral joint when used indiscriminately. Many scientific contributions on the topic notably in the last two decades have increased the understanding of patellofemoral instability. The comprehensive knowledge of the causes for a persisting instability of the patella has made the treatment more efficient and precise but also more complex.

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.

Avoiding Complications with MPFL Reconstruction

PURPOSE OF REVIEW

To discuss the potentially significant complications associated with medial patellofemoral ligament (MPFL) reconstruction. Additionally, to review the most current and relevant literature with an emphasis on avoiding these potential complications.

RECENT FINDINGS

Multiple cadaveric studies have characterized the anatomy of the MPFL and the related morphologic abnormalities that contribute to recurrent lateral patellar instability. Such abnormalities include patella alta, excessive tibial tubercle to trochlear grove (TT-TG) distance, trochlear dysplasia, and malalignment. Recent studies have evaluated the clinical outcomes associated with the treatment of concomitant pathology in combination with MPFL reconstruction, which is critical in avoiding recurrent instability and complications. Although there remains a lack of consensus regarding various critical aspects of MPFL reconstruction, certain concepts remain imperative. Our preferred methods and rationales for surgical techniques are described. These include appropriate work up, a combination of procedures to address abnormal morphology, anatomical femoral insertion, safe and secure patellar fixation, appropriate graft length fixation, and thoughtful knee flexion during fixation.

Clinical Outcome of Arthroscopic Lateral Retinacular Release for Symptomatic Bipartite Patella in Athletes

PURPOSE

To report the results of arthroscopic lateral retinacular release without excision of the accessory fragment for treatment of symptomatic bipartite patella with a minimum 2-year follow-up.

METHODS

We retrospectively reviewed all cases of symptomatic type III bipartite patella confirmed by radiographs, computed tomography, and magnetic resonance imaging and treated with arthroscopic lateral release from 2005 to 2015. Patients with history of knee fractures or surgery, concomitant meniscal or anterior cruciate ligament (ACL) procedures, and severe arthritic changes of the patellofemoral joint were excluded. Patients were assessed by Kujala score, visual analog scale (VAS), Tegner Activity Scale (TAS), and time to return to sporting activities.

RESULTS

Ten patients (11 knees) were clinically reassessed after 69.6 ± 33.3 (range: 25-132; 95% confidence interval [CI]: 47.29-91.99) months from surgery. There was a significant improvement in Kujala (P < .05) and VAS scores (P < .05), and no differences were found between pre- and postoperative TAS scores (P > .05). No complications occurred during the follow-up period. All patients returned to sport after 42.3 ± 11.3 (range: 30-60; 95% CI: 34.71-49.84) days after surgery.

CONCLUSIONS

The arthroscopic lateral retinacular release of a symptomatic type III bipartite patella without excision of the accessory fragment allowed early return to sporting activities, with excellent symptom relief. Patients had significantly improved mean Kujala and VAS scores without a decrease in the mean TAS scores.

LEVEL OF EVIDENCE

Level IV, case series.

Editorial Commentary: Got Evidence? What We Really Need Is an Algorithm for Treating Symptomatic Bipartite Patella

Bipartite patella is an uncommon but potentially troublesome problem for young athletes. Numerous uncontrolled retrospective studies have reported good results after various treatments. What is needed are studies that will guide workup and support treatment decisions based on the condition of the cartilage surfaces of the fragment, presence of pseudoarthrosis, and size and location of the fragment. To support decisions, we need prospective comparative studies, either randomized or, at least, prospective cohort studies that identify patients at the time of presentation, document key decision points, and follow patients to successful resolution of symptoms.

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.

The Relationship of Static Tibial Tubercle-Trochlear Groove Measurement and Dynamic Patellar Tracking

BACKGROUND

The tibial tubercle to trochlear groove (TT-TG) distance is used for screening patients with a variety of patellofemoral joint disorders to determine who may benefit from patellar medialization using a tibial tubercle osteotomy. Clinically, the TT-TG distance is predominately based on static imaging with the knee in full extension; however, the predictive ability of this measure for dynamic patellar tracking patterns is unknown.

PURPOSE

To determine whether the static TT-TG distance can predict dynamic lateral displacement of the patella.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

The static TT-TG distance was measured at full extension for 70 skeletally mature subjects with (n = 32) and without (n = 38) patellofemoral pain. The dynamic patellar tracking patterns were assessed from approximately 45° to 0° of knee flexion by use of dynamic cine-phase contrast magnetic resonance imaging. For each subject, the value of dynamic lateral tracking corresponding to the exact knee angle measured in the static images for that subject was identified. Linear regression analysis determined the predictive ability of static TT-TG distance for dynamic patellar lateral displacement for each cohort.

RESULTS

The static TT-TG distance measured with the knee in full extension cannot accurately predict dynamic lateral displacement of the patella. There was weak predictive ability among subjects with patellofemoral pain ( r² = 0.18, P = .02) and no predictive capability among controls. Among subjects with patellofemoral pain and static TT-TG distances 15 mm or more, 8 of 13 subjects (62%) demonstrated neutral or medial patellar tracking patterns.

CONCLUSION

The static TT-TG distance cannot accurately predict dynamic lateral displacement of the patella. A large percentage of patients with patellofemoral pain and pathologically large TT-TG distances may have neutral to medial maltracking patterns.

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.

The Tibial Tubercle-Trochlear Groove Distance Is Greater in Patients With Patellofemoral Pain: Implications for the Origin of Pain and Clinical Interventions

BACKGROUND

The distance between the tibial tubercle (TT) and trochlear groove (TT-TG distance) is known to be greater in patients with patellar instability. However, the potential role and prevalence of pathological TT-TG distances in a large cohort of skeletally mature patients with isolated patellofemoral pain (PFP) are not clear.

PURPOSE

To determine if the mean TT-TG distance is greater in patients with PFP, who lack a history of patellar dislocations, knee trauma, or osteoarthritis, relative to healthy controls.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 50 knees (38 patients) with PFP and 60 knees (56 controls) without PFP formed the basis of this study. Magnetic resonance imaging was used to determine the TT-TG distance from 3-dimensional static scans.

RESULTS

The cohort with PFP demonstrated a significantly greater mean TT-TG distance relative to asymptomatic controls (13.0 vs 10.8 mm, respectively; P = .001). Among the cohort with PFP, 15 knees (30%) demonstrated TT-TG distances ≥15 mm, and 3 knees (6%) demonstrated TT-TG distances ≥20 mm.

CONCLUSION

Most adult patients with isolated PFP have elevated TT-TG distances compared with controls, which likely contributes to the force imbalance surrounding the knee.

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.

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.