Omer A. Ilahi

Cyclic Pull-Out Strength of Hamstring Tendon Graft Fixation with Soft Tissue Interference Screws Influence of Screw Length

Blunt-threaded interference screws used for fixation of hamstring tendons in anterior cruciate ligament reconstructions provide aperture fixation and may provide a biomechanically more stable graft than a graft fixed further from the articular surface. It is unknown if soft tissue fixation strength using interference screws is affected by screw length. We compared the cyclic and time-zero pull-out forces of 7 25 mm and 7 40 mm blunt-threaded metal interference screws for hamstring graft tibial fixation in eight paired human cadaveric specimens. A four-stranded autologous hamstring tendon graft was secured by a blunt-threaded interference screw into a proximal tibial tunnel with a diameter corresponding to the graft width. Eight grafts were secured with a 25-mm length screw while the other eight paired grafts were secured with a 40-mm length screw. During cyclic testing, slippage of the graft occurred as the force of pull became greater with each cycle until the graft-screw complex ultimately failed. All grafts failed at the fixation site, with the tendon being pulled past the screw. There were no measurable differences in the mean cyclic failure strength, pull-out strength, or stiffness between the two sizes of screws. Although use of the longer screw would make removal technically easier should revision surgery be necessary, it did not provide stronger fixation strength than the shorter, standard screw as had been postulated.

Post-Traumatic Heterotopic Ossification About the Elbow

To evaluate the effect of surgical timing on the formation of heterotopic ossification about the elbow, 71 consecutive patients with elbow trauma requiring operative management were evaluated. Fourteen patients were excluded because they suffered from head injury, burns, or severe open injuries requiring surgery on two or more occasions. Sixteen patients were lost to follow-up, leaving a group of 41 patients. The average age of patients was 35 years. The fractures involved the olecranon in 19, distal humerus in 12, and radial head/neck in 10 patients. Six of these fractures were accompanied by a dislocation. Eleven were open injuries; the remaining 30 were closed. Bone grafting was performed in nine patients. The interval between injury and surgical intervention averaged 57 hours. None (0%) of 17 patients treated within 48 hours developed grade II, III, or IV heterotopic ossification, whereas 8 (33%) of 24 patients treated after 48 hours developed grade II, III, or IV heterotopic ossification. There were no significant differences in demographic or injury parameters between these two groups. These findings suggest that fixation of unstable elbow fractures within 48 hours of injury may reduce the formation of ectopic bone.

Security of Knots Tied with Ethibond, Fiberwire, Orthocord, or Ultrabraid:

Background The security of several popular arthroscopic knots to prolonged, incremental, cyclic loads is unknown, as is the security of knots tied with newer, superstrong sutures. Hypothesis Some arthroscopic knots are as secure as openly tied square knots, and knots tied with superstrong sutures are more secure than those tied with braided polyester. Some arthroscopic knots are significantly bulkier than openly tied square knots. Study Design Controlled laboratory study. Methods Five types of openly tied knots (3-throw square, 4-throw square, 5-throw square, 5-throw slip, open SAK [simple arthroscopic knot]), 6 complex arthroscopic knots backed with 3 reversed half-hitches with alternating posts (RHAPs) (SMC, Weston, taut-line hitch, Tennessee slider, Roeder, Duncan loop), and 2 stacked half-hitch (SHH) arthroscopic knots (surgeons [S=S=S//xS//xS//xS], SAK [S=S//xSxS//xS]) were tied using No. 2 Ethibond around 2 aluminum rods, which were pulled apart with stepwise, incremental, cyclic loads to a maximum force of 120 N (2250 total cycles). Then, 5-throw square knots openly tied with No. 2 Fiberwire, Orthocord, or Ultrabraid were subjected to the stepwise, incremental, cyclic loading protocol extended to a 260-N load level. Before mechanical testing, the height (maximum diameter) of each knot was measured with digital calipers. Results For Ethibond, the openly tied 3-throw square knots (56.2 ± 21.4 N) and 5-throw slip knots (49.9 ± 26.9 N) reached clinical failure (3 mm of laxity) at significantly lower loads (P < .05) than openly tied 5-throw square knots (90.8 ± 6.5 N), whereas the openly tied SAK (82.3 ± 9.4 N) and 4-throw square (84.3 ± 11.6 N) and all arthroscopically tied knots reached 3 mm of laxity at statistically similar loads. Five-throw square knots openly tied with Fiberwire or Orthocord reached 3 mm of laxity at much higher loads (194.9 ± 28.4 N and 168.4 ± 8.6 N, respectively) than those tied using Ethibond (P < .001 for each comparison), but there was no significant difference in performance between Fiberwire knots and Orthocord knots. Although Ultrabraid square knots also were stronger than those tied with Ethibond (137.9 ± 15.9 N, P < .005), they were not as secure as those tied with Orthocord or Fiberwire (P < .05). Compared with the 5-throw square knots, all arthroscopic knots were significantly bulkier. Especially bulky knots were the Duncan loop and the taut-line hitch. Orthocord square knots demonstrated bulkiness similar to Ethibond square knots, whereas Fiberwire and Ultrabraid square knots were significantly bulkier. Conclusions For braided suture, 5-throw knots optimize square knot security. Open or arthroscopic slip knots can achieve similar security with post switching and loop reversal. Fiberwire, Orthocord, or Ultrabraid openly tied square knots offer greater security than those tied with Ethibond. Arthroscopic knots vary in their bulkiness, but all are significantly bulkier than 5-throw openly tied square knots. Square knots openly tied with Fiberwire or Ultrabraid tend to be bulkier than if tied with Ethibond or Orthocord, which are similar to each other. Clinical Relevance The 5-throw openly tied square knot remains the gold standard, although the openly tied SAK offers similar security when tying in a hole. Arthroscopic knots, whether complex knots backed up by 3 RHAPs, the 6-throw surgeons knot, or the 5-throw SAK, give security similar to the standard. Square knots tied with the newer sutures in open fashion are more secure than if tied with braided polyester. Using lower profile knots may be especially important when employing Fiberwire or Ultrabraid, as these sutures tend to result in bulkier knots than those tied with Ethibond or Orthocord.

Continuous epidural analgesia using fentanyl and bupivacaine after total knee arthroplasty

Eighty consecutive patients undergoing unilateral total knee arthroplasty received postoperative analgesia consisting of a continuous epidural infusion of fentanyl and bupivacaine. Nineteen patients (24%) were unable to complete the three-day course of epidural infusion: two thirds for technical reasons and one third because of adverse effects. The remaining 61 patients (76%) successfully completed the 72-hour protocol. The benefits in this group included a shorter hospital stay (8.3 versus 9.5 days, p < 0.01) and earlier return of flexion (p < 0.05) as compared with the group that had the epidural catheter removed prematurely. When compared with previous experiences with continuous epidural analgesia using Duramorph and bupivacaine for the first three days after TKA in 56 patients, the current group of 80 patients had shorter average hospitalization (8.6 versus 9.7 days, p < 0.01) and earlier return of flexion (p < 0.001). Patient acceptance was excellent with either agent. Confusion and pruritus were significantly less common with fentanyl, but the incidence of hypotension was increased. Nausea was problematic in both groups. The incidence of respiratory depression was 5% for either opiate. The degree of hypoventilation and treatment required for it were less severe with fentanyl, however.

Femoral tunnel length: accessory anteromedial portal drilling versus transtibial drilling.

PURPOSE To determine whether drilling using an anteromedial portal technique during single-bundle anterior cruciate ligament (ACL) reconstruction risks creating femoral tunnels less than 25 mm long in the clinical setting. METHODS Intraoperative measurements of femoral tunnel length in a group of 35 consecutive patients undergoing single-bundle primary ACL reconstruction with transtibial (TT) femoral drilling were compared with a subsequent group of 80 consecutive patients undergoing the same procedure with accessory anteromedial portal (AAMP) femoral drilling. The length of femoral tunnels created through the AAMP in male patients was compared with that in female patients, and the expected likelihood of obtaining tunnels shorter than 25 mm was determined for either gender. RESULTS The mean femoral tunnel length in the AAMP group was significantly shorter than that in the TT group (35.6 mm and 40.7 mm, respectively; P < .0001). In male patients in the AAMP group, the femoral tunnel length was significantly greater on average than that in female patients in the same group (36.8 mm and 33.5 mm, respectively; P = .0001). The shortest measured femoral tunnel was 28 mm long. The statistical likelihood of femoral tunnels created by AAMP drilling being less than 25 mm in length was 0.47% for female patients and 0.1% for male patients. CONCLUSIONS Although femoral tunnel length with AAMP drilling is, on average, approximately 5 mm (12.5%) shorter than with TT drilling, the likelihood of the tunnel being too short to allow for suspensory fixation with adequate graft placed within the femoral tunnel is very low. Female patients undergoing single-bundle ACL reconstruction with AAMP drilling have a femoral tunnel length that is approximately 3 mm (9%) shorter than that in male patients on average, but the expected likelihood of obtaining a tunnel shorter than 25 mm in female patients is still less than 1:200, compared with 1:1,000 for male patients. LEVEL OF EVIDENCE Level III, retrospective comparative study.

Intraosseous Innervation of the Human Patella A Histologic Study

Background The soft tissue structures surrounding the human knee joint have been the subject of extensive anatomic study. The detailed histologic findings within the bone of the human patella, however, have not been systematically studied. While the nerves supplied to the periarticular soft tissues have been very well documented, the nerves supplied to the interior of the bony patella have never been described. Hypothesis This study tests the hypothesis that the patella contains an intraosseous nerve network. Further, the authors investigate the anatomic location of these intraosseous nerves to better understand their possible clinical relevance. Study Design Descriptive laboratory study. Methods Ten matched pairs of cadaveric patellae (left and right patellae from the same individual; 20 total) were prepared for evaluation by hematoxylin and eosin staining using a technique that allows the creation of complete, large histologic sections of individual patellae. The matched specimens were dissected free of soft tissue and then sectioned using a diamond-wafering saw into 3-mm sagittal (left patella) and transverse (right patella) sections. Sections were then decalcified and whole-mounted into paraffin blocks for further sectioning using a large-format microtome. All 20 specimens were prepared for evaluation. Age at death averaged 80 years (range, 64-91). All specimens demonstrated at least grade II chondromalacia. Results Nineteen of 20 (95%) specimens demonstrated intraosseous nerves. Of 248 sections studied, 116 (47%) demonstrated intraosseous nerves, with 227 individual nerves identified. The density of intraosseous nerves was greatest in the medial and central portions of the patella, with a significant paucity identified laterally. Conclusion The primary intraosseous innervation of the patella derives from a medially based neurovascular bundle. Clinical Relevance A better understanding of the nerves within the human bony patella may improve understanding the patho-physiology of anterior knee pain syndromes.

Classification of Anterosuperior Glenoid Labrum Variants and Their Association With Shoulder Pathology

UNLABELLED This prospective study of 367 consecutive shoulder arthroscopies assessed variants of the anterosuperior glenoid labrum and associated shoulder pathology. Thirty-three shoulders were excluded because of prior surgery, septic arthritis, or adhesive capsulitis. Anterosuperior glenoid variants were classified as: type I, cordlike middle glenohumeral ligament without sublabral foramen; type II, sublabral foramen without a cordlike middle glenohumeral ligament; type III, sublabral foramen with a cordlike middle glenohumeral ligament; and type IV, absent anterosuperior labrum with the anterior aspect of the superior labrum continuous with a cordlike middle glenohumeral ligament. The presence of these variants was correlated with the incidence of shoulder pathology found on arthroscopic inspection. Of 334 shoulders, 118 (35.3%) had variants of the anterosuperior glenoid labrum. Of these, 32 (27.1%) were type I, 27 (22.9%) were type II, 34 (28.8%) were type III, and 25 (21.2%) were type IV. The incidence of advanced superior labrum anterior-posterior lesions in the 86 shoulders displaying a type II, III, or IV variant was significantly higher than in shoulders with no anterosuperior variant (48.8% versus 23.6%, P<.001). Other pathologic findings were not significantly increased in shoulders with variants compared to those without. LEVEL OF EVIDENCE Level 1.

Interobserver variability of the Insall-Salvati ratio.

Thirty six patients presenting with knee pain were enrolled in a prospective study to assess the variability of the radiographic measurement of patellar height by the traditional and modified Insall-Salvati ratios. The traditional and modified Insall-Salvati ratios were measured from a lateral knee radiograph using a standard hand-held ruler by four physicians in varying order. The observers were in agreement in classifying the radiographs in two thirds of the cases When the traditional method was used but in less than one-half of the cases when the modified ratio was used. The source of the difference in the two ratios is a greater variability in measuring the distance from the inferior margin of the articular surface to the tibial tubercle.

Relationship of musculotendinous junction location to harvested semitendinosus and gracilis tendon length

Background: Harvested hamstring tendon length has received scant attention in published anterior cruciate ligament (ACL) reconstruction literature, yet length can limit the ability to increase graft diameter by folding the tendon over more than once. Indeed, some ultrashort tendons may be too short to yield a clinically useful graft after being folded over just once. Ultimately, the total length of a harvested hamstring tendon may depend on the length of the tendon distal to its musculotendinous (MT) junction. Purpose: To compare the lengths of harvested hamstring tendons to the location of the MT junction to help predict abnormally short tendon harvest. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Eighty-four consecutive patients undergoing primary ACL reconstruction using hamstring tendon autografts underwent intraoperative measurement of the total length of each harvested semitendinosus (ST) and gracilis (G) tendon, as well as the distance from the MT junction to that tendon’s distal end (ie, the “tendon-only” length). Results: The ratio of the tendon-only portion to total harvested tendon length averaged 0.52 (range, 0.39-0.71) for the ST and 0.52 (range, 0.43-0.71) for the G, suggesting a 95% chance of harvesting a tendon <15 cm in length for the tendon-only portion is <6.45 cm for ST or <6.75 cm for G tendons. There was moderate correlation between the lengths of harvested ST and G tendons with patient height as well as with the diameter of the combined, quadruple-stranded graft. Conclusion: The ratio of the tendon-only length to total harvested length for both the ST and G appear to range from approximately 0.4 to 0.7. Patients with abnormally distal MT junctions of either their ST or G are likely to have an abnormally short harvest of that tendon, even in the absence of technical harvesting error.

Anatomic and radiographic analysis of arthroscopic tack placement into the anteroinferior glenoid.

Tack location within the anteroinferior aspect of the glenoid when performing simulated repairs of anteroinferior capsulolabral avulsions (Bankart lesions) was evaluated anatomically and radiographically. Arthroscopy was performed on six fresh-frozen cadaveric shoulders, and bioabsorbable tacks were placed through an accessory anteroinferior portal coming into the joint just above the subscapularis tendon using an outside-in technique. Tack location was studied after removal of all soft tissues. In addition to their position on the glenoid, the tacks were also evaluated for being partially or completely within bone. The tacks were recannulated with guide pins and anteroposterior, axillary, and en face glenoid radiographs of each specimen were obtained. This study provides quantitative data about the inferior placement limitations of the insertion angle and location of fixation devices within the anteroinferior glenoid through the anteroinferior accessory portal.