Unpacking the Tibial Tubercle-Trochlear Groove Distance: Evaluation of Rotational Factors, Trochlear Groove and Tibial Tubercle Position, and Role of Trochlear Dysplasia.

BACKGROUND: The tibial tubercle to trochlear groove (TT-TG) distance is often utilized for determining the surgical treatment for patients with patellar instability (PI). It is thought to directly represent the position of the TT on the tibia. Recent work has shown that the measurement of the TT-TG distance is multifactorial. PURPOSE: To investigate the relationship between relative tibial external rotation (rTER) and trochlear dysplasia (TD), as well as the location of the TG and TT in patients with and without PI, and to correlate these and other anatomic measurements with the TT-TG distance. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 89 patients with PI who underwent magnetic resonance imaging were identified with 92 matched control patients. A standardized measurement protocol on axial magnetic resonance imaging determined rTER, the proximal and distal TG lateralization (pTGL and dTGL, respectively) ratios, and the TT lateralization (TTL) ratio. Other measures of interest included the lateral trochlear inclination angle, sulcus angle, and lateral patellar inclination angle. Univariate regression was used to determine the associations of TD (lateral trochlear inclination angle, sulcus angle) with rTER and the TG position, and multivariate regression was used to model associations among all the variables with the proximal and distal TT-TG distances. RESULTS: rTER was significantly higher in the study group (P < .001), and univariate regression showed a significant association between dysplasia measures and rTER (P < .001). The pTGL ratio was lower in the study group (P = .025), but there was no difference in the dTGL ratio (P = .090) or the TTL ratio (P = .098) between the groups. There were no associations between dysplasia measures and the pTGL and dTGL ratios (P > .05). Multivariate regression showed that the proximal TT-TG distance is predicted by the sulcus angle, pTGL ratio, rTER, and TTL ratio (P < .05) and that the distal TT-TG distance is predicted by the lateral patellar inclination angle, dTGL ratio, sulcus angle, rTER, and TTL ratio (P < .05). CONCLUSION: rTER had a significant association with TD. The position of the proximal TG was more medial in patients with PI. There was no significant difference in the TTL ratio between patients with and without PI. The TT-TG distance was associated with multiple anatomic measures and was not solely predicated on the position of the TT.

Patellar Height Correlates Modestly With Trochlear Dysplasia: A Magnetic Resonance Imaging Analysis.

Purpose: To evaluate whether there is a correlation between the position of the patella and trochlear morphology in patients with and without patellar instability using exclusively MRI measurements. Methods: MRI scans of knees in patients with patellofemoral instability and knees of patients with an ACL (anterior cruciate ligament) tear as a control group were reviewed. Measurements of patellar position (Canton-Deschamps ratio, Patellar Trochlear Index, and lateral patellar inclination) and trochlear morphology (lateral trochlear inclination and sulcus angle) were obtained from each scan. Bivariate and multivariate analysis was performed to identify correlations between study group, demographics, and patellofemoral joint measurements. Results: There were 70 knees in the patellofemoral instability group and 60 knees in the control group. Bivariate analysis showed a significant difference in all measurements between the patellar instability group and the control group. Multivariate analysis showed modest correlations between patellar position and trochlear morphology. The Caton-Deschamps (CD) ratio correlated with patellar trochlear index (P < .001) and lateral trochlear inclination (P < .001). The respective R-square goodness of fit was 41.1%. Patellar trochlear index correlated with CD ratio (P < .001), lateral trochlear inclination (P < .001), lateral patellar inclination (P < .001), and patellar instability group (P = .011). The R-sq goodness of fit was 37.3%. Lateral patellar inclination correlated with patellar trochlear index (P < .001), Lateral trochlear inclination (P < .001), and age at first dislocation or injury (P = .02). The R-sq goodness of fit was 68.56%. Conclusions: Using MRI-based measurements of the patellofemoral joint, we identified modest, but significant, correlations between measures of patellar height (patellar trochlear index, CD ratio, and lateral patellar inclination) and trochlear dysplasia. This correlation is unclear and is likely multifactorial, but on the basis of this work, a causal relationship between trochlear dysplasia and patella alta cannot be established. Clinical Relevance: Radiographic evaluation of the patella and how it relates to the surrounding boney anatomy provides important information regarding our understanding of patella instability and its treatment.

Patellar Tendon Imbrication for Patella Alta.

Patella alta is a significant contributor to patellar instability. Historically, distalizing tibial tubercle osteotomy has been recommended for this problem; however, complications such as nonunion, fracture and hardware irritation are concerning. Additionally, the procedure cannot be performed on skeletally immature patients without violation of the proximal tibial physis. The authors describe a technique of patellar tendon imbrication that does not involve hardware or osteotomy. This technique allows for reliable correction of patella alta and provides patellar stability without the complications associated with osteotomy.

Discoid Lateral Meniscus Saucerization and Treatment of Intrasubstance Degeneration Through an Accessory Medial Portal Using a Small Arthroscope.

Discoid lateral meniscus (DLM) is a rare meniscal variant characterized by an increased amount of meniscal tissue that resembles the shape of a disc as opposed to the typical crescent shape of the lateral meniscus. Surgical intervention is recommended for symptomatic DLM with persistent pain, mechanical symptoms, or motion impairment. The technique described is a reliable and reproducible method to identify and treat intrasubstance degeneration (ID) in the setting of DLM. A small arthroscope is used that allows more room for a meniscal repair device, as well as improved visualization and access of the lateral compartment. An accessory medial portal is used that allows perpendicular access to the anterior half of the body, as well as the posterior aspect of the anterior horn for repair. Successful surgery with this technique preserves meniscus and produces a strong reliable all-meniscal based repair of ID that allows early weight bearing and range of motion postoperatively.

Medial Patellofemoral Ligament Reconstruction and Lateral Retinacular Lengthening from a Lateral Approach.

The medial patellofemoral ligament (MPFL) is frequently torn and attenuated in patients with acute or chronic patellar instability. The mainstay for surgical treatment has become MPFL reconstruction to reestablish the checkrein to lateral patellar translation. The authors describe a technique for MPFL reconstruction with concomitant lateral retinacular lengthening with a gracilis allograft and adjustable loop cortical femoral fixation performed chiefly from a lateral parapatellar approach. This technique allows for reliable retensioning of the medial and lateral patellar soft tissues while avoiding complications associated with techniques that use interference screw fixation. Successful execution of this procedure provides a strong MPFL construct that allows patients to undergo early aggressive rehabilitation and return to activities.

Decreased Colony-Forming Ability of Subacromial Bursa-Derived Cells During Revision Arthroscopic Rotator Cuff Repair.

PURPOSE: To compare the cellular viability and differentiation potential of subacromial bursa-derived cells (SBDCs) located over the rotator cuff muscle and tendon of patients undergoing primary versus revision arthroscopic rotator cuff repair (ARCR). METHODS: Subacromial bursa was harvested from 18 primary (57.1 ± 4.6 years) and 12 revision ARCRs (57.3 ± 6.7 years). Bursa was collected from 2 sites (over rotator cuff tendon and muscle), digested with collagenase, and grown in culture. The number of nucleated cells, colony-forming units (CFUs), differentiation potential, and mesenchymal stem cell surface markers were compared in primary and revision cases. RESULTS: There was no difference in the number of nucleated cells between primary and revision ARCR harvested from the subacromial bursa overlying the tendon (3019.3 ± 1420.6 cells/mg and 3541.7 ± 2244.2 cells/mg, respectively; P = .912) or muscle (2753.5 ± 1547.1 cells/mg and 2989.0 ± 2231.4 cells/mg, respectively; P = .777). There was no difference in the number of CFUs between primary and revision ARCR over the rotator cuff tendon (81.5 ± 49.5 CFUs and 53.0 ± 36.9 CFUs, respectively; P = .138), but there were significantly fewer CFUs over the muscle in revision cases (28.1 ± 22.7 CFUs) compared with primary cases (55.7 ± 34.5 CFUs) (P = .031). SBDCs from revision ARCR expressed characteristic mesenchymal stem cell surface epitopes and had multidifferentiation potentials for chondrogenesis, osteogenesis, and adipogenesis. CONCLUSIONS: SBDCs harvested over the rotator cuff muscle demonstrated significantly decreased colony-forming abilities in revision arthroscopic rotator cuff repairs compared with primary repairs. However, the subacromial bursa retains its pluripotent differentiation potential for chondrogenic, osteogenic, and adipogenic lineages in the revision setting. CLINICAL RELEVANCE: The subacromial bursa may play a role in the healing response of the repaired rotator cuff. This capacity is not necessarily diminished in the revision setting and may be harnessed as an orthobiologic.

Patellofemoral Joint Contact Pressures: Current Concepts and Use in Patellar Instability Studies.

The patellofemoral joint is thought to be a common source for knee pain. Improper alignment and function of the patellofemoral joint can lead to abnormal contact pressures, which may explain patients' symptoms. In this review, the authors examine techniques for measuring patellofemoral joint contact pressures and summarize the relevant patellofemoral joint anatomy and contact pressures in normal knee kinematics. Finally, they discuss the results of studies investigating contact pressure changes in cases of patellar instability. This includes both reconstruction of the medial patellofemoral ligament and tibial tubercle osteotomy. [Orthopedics. 2019; 42(2):e172-e179.].

T1-T2 Disk Herniation Presenting With Horner Syndrome: A Case Report With Literary Review.

Horner syndrome or oculosympathetic paresis is caused by interruption of the sympathetic nerve supply to the face and eye that manifests as facial anhidrosis, blepharoptosis, and miosis. This sympathetic pathway begins in the hypothalamus and synapses in the intermediolateral gray substance of the spinal cord at C8-T2 levels making it susceptible to disruption via a high thoracic intervertebral disk herniation. We present a rare case of a patient with T1-T2 intervertebral disk herniation and Horner syndrome who was treated surgically. After confirming the diagnosis with MRI, the patient was treated with standard posterior approach with laminoforaminotomy and diskectomy. Although posterior approach surgery is most commonly used for laminectomy and/or foraminotomy, successful anterior approaches to upper thoracic lesions are valid as well. Our patient had resolution of his back pain, paresthesias, and grip weakness at 6 weeks postoperatively, but his Horner syndrome persisted at latest follow-up. Patients with cervical radiculopathy symptoms and physical examination findings consistent with Horner syndrome should be evaluated with a MRI that includes the upper thoracic spine. An accurate diagnosis and timely surgical intervention may provide the patient the best chance for regression of symptoms and a satisfactory outcome.