Anterior knee pain is a frequent musculoskeletal complaint affecting all ages, both sexes, athletes, and nonathletes alike. Numerous theories have been proposed regarding its etiology including patellar malalignment, quadriceps insufficiency, subluxation, quadriceps muscle tightness, and chondral defects. However, the mechanism by which these factors produce this pain is not clear. Knowledge of the distribution of nociceptive nerve fibers around the knee would seem to provide insight in treating these painful conditions. Eleven human patellae--eight specimens from patients with degenerative patellofemoral disease and three normals--were evaluated. Immunohistochemical techniques using monoclonal antibody to substance-P were employed to identify nociceptive fibers. Substance-P is a nociceptive neurotransmitter found in afferent nerve fibers. Substance-P fibers were isolated in the retinaculum, fat pad, periosteum, and subchondral plate of patellae affected with degenerative disease. This study demonstrates that selective tracting of nociceptive pain fibers is possible around the knee both in soft tissue and, in some circumstances, bone. The subchondral plate of normal patellae did not demonstrate erosion channels, but those with chondral defects from degenerative disease did. Nociceptive fibers found in these defects may explain the origin of symptoms in some patients. The distribution of substance-P nerve fibers in the soft tissues around the knee suggests that denervation may be the mechanism by which surgical procedures for anterior knee pain produce favorable results.

Innervation of the human knee joint by substance-P fibers.

Forty-five arthroscopic lateral releases were reviewed with a follow-up from 2 to 6 years (average 4 years). Satisfactory results were obtained in 60% of the patellar pain group (20 knees) and 68.5% of the instability group (19 knees). The results in osteoarthrosis (6 knees) were unsatisfactory. Postoperative hemarthrosis was infrequent (2.2%). Unfavorable prognostic factors are an incomplete release with an insufficient postoperative passive patellar tilt in the pain group and more than five preoperative dislocations in the instability group. After failure of conservative treatment, a lateral release can be reasonably used in pain syndromes with a tight lateral retinaculum and lateral patellar tracking and in milder cases of instability.

Arthroscopic lateral release for patellar pain or instability

We initiated a study to look at preoperative, flexed-knee, midpatellar computed tomography (CT) scans and intraoperative arthroscopic findings of lateral patellar articular degeneration in predicting the results after lateral retinacular release for failed nonoperative treatment of anterior knee pain. Twenty patients with 30 painful knees underwent preoperative flexed-knee, midpatellar CT scans that were retrospectively classified by the method of Fulkerson into normal alignment, lateral subluxation, lateral patellar tilt, and combined tilt and subluxation. Arthroscopy was performed before open lateral release. The lateral facet of the patella was graded as either minimal changes (Outerbridge I or II) or advanced (Outerbridge III or IV) changes. Patients were followed for a minimum of 2 years and graded on a standard patellofemoral rating scale. Only 22 of 30 knees that were thought to be clinically malaligned, actually were malaligned by CT scan; eight CT scans were interpreted as normal. The results were further stratified into group A (CT-documented tilt, minimal facet changes), group B (CT-documented tilt, advanced facet changes), and group C (normal CT). Ninety-two percent of group A were rated good or excellent. Twenty-two percent of Group B rated good/excellent, 33% fair, 44% poor. Only 13% of group C rated good (one patient). Based on the results of the study, we recommend lateral release for anterior knee patients with CT-proven patellar tilt who have not responded to conservative treatment and have minimal facet changes with minimal or no subluxation. Lateral retinacular release should not be offered as a treatment to the patient with a normally aligned patella because poor results will most likely result.

Preoperative computed tomography scanning and arthroscopy in predicting outcome after lateral retinacular release

The purpose of this study was as follows: 1) to review our previous findings regarding surgical outcome fol lowing open retinacular release but now at a mean followup of 4 years, 2) to test the validity of the correc tion of patellar "overhang" by Merchant views at 4 years and correlate this with outcome, 3) to correlate arthros copic findings of lateral overhang, patellofemoral carti lage disease, preoperative Q-angle measurements, and duration of symptoms with outcome at 4 years postre lease. The surgical technique of diagnostic arthroscopy and open longitudinal release has been described pre viously by the author, emphasizing the specific anatom ical structures to be divided. The synovium was never incised and the retinacular structures were freed to allow reduction of the patella medially. Sixty patients comprising 76 knees were reviewed at a mean followup of 4 years postrelease. Followup included evaluation of Merchant views and Q angles, physical examination, and determination of patient satisfactio...

Diagnostic arthroscopy and longitudinal open lateral release A four year follow-up study to determine predictors of surgical outcome

The role of the lateral retinaculum in patellofemoral instability is still debated. Lateral retinacular release (LRR), has been extensively performed in combination with different surgical procedures, including reconstruction of medio-patellofemoral ligament (MPFL). Despite controversial indications, the results from these studies seem promising. The present study conducts a systematic review about current biomechanical and clinical evidence concerning the role of LRR in combination with MPFL reconstruction. We performed a comprehensive literature research, comparing the outcomes of MPFL reconstruction with and without LRR. This systematic review was conducted according to the PRISMA guidelines. The literature search was performed in August 2020. All articles describing the outcome of isolated MPFL reconstruction alone or in combination with a LRR in patients with recurrent patellofemoral instability were considered for inclusion. Only articles reporting data on patients with a minimum of 12-month follow-up were included. Only articles reporting quantitative data under the outcomes of interest were included. A total of 63 articles were eligible for this systematic review, including 2131 knees. The mean follow-up was 40.87 ± 24.1 months. All scores of interests improved in favour of the combined group: Kujala + 3.8% (P = 0.01), Lysholm + 4.2% (P = 0.004), Tegner + 0.8 points (P = 0.04), IKDC + 9.8% (P = 0.02). The ROM was comparable between the two groups (P = 0.4). Similarity was found in terms of positivity to the apprehension test (P = 0.05), rate of complications (P = 0.1), re-dislocations (P = 0.8), and revision surgeries (P = 0.1). There is no evidence that adding a lateral release impacts positively on the outcome of MPFL reconstruction. Level of evidence: IV, Systematic review

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Lateral retinacular release combined with MPFL reconstruction for patellofemoral instability: a systematic review

Lateral release is a reliable component of any surgical treatment of patellofemoral dysfunction or “chondromalacia patella,” good to excellent results in approximately 80% of cases having been reported by numerous investigators. This study confirms the efficacy of the procedure and highlights the features of the open technique as compared with the arthroscopic method. We advocate diagnostic arthroscopy for complete evaluation of the joint. Particular attention is drawn to the anatomic structures that must be divided and the care taken to secure hemostasis to optimize results. Since no correlation was found between the severity of chondromalacia and the final results, this study casts doubt on the value of shaving the rough articular surface.

Andrew Strokon

Papers

Diagnostic arthroscopy and longitudinal open lateral release: A safe and effective treatment for “chondromalacia patella”