Peter T. Simonian

Early results of percutaneous iliosacral screws placed with the patient in the supine position.

Summary The operative management of pelvic ring fractures and dislocations is difficult. Posterior pelvic ring disruptions are often associated with severe soft-tissue injuries and high infection rates. Percutaneous iliosacral screw fixation of the posterior pelvis has become popular with improved fluoroscopic imaging techniques. The percutaneous iliosacral screw technique after closed reduction of the posterior pelvic disruption minimally violates the soft-tissue envelope and should diminish both the operative blood loss and infection rate. The early results and complications are documented in our first 68 patients.

Closed reduction and percutaneous skeletal fixation of sacral fractures.

Closed manipulative reduction and percutaneous fixation of a displaced sacral fracture is a treatment alternative that offers several advantages. The fracture is reduced and stabilized without an extensile surgical exposure. The risks of surgical wound problems, especially infection, are lessened. Operative and anesthesia times are decreased by using percutaneous techniques of reduction and fixation. Blood loss is also minimized by the percutaneous procedure. Sacral nonunion after this technique is rare. The procedure is dependent on quality fluoroscopic pelvic imaging, a thorough understanding of the posterior pelvic anatomy and early operative intervention, especially in patients with severe posterior pelvic deformities.

Radiographic evaluation of glenohumeral kinematics: A muscle fatigue model

The purpose of this study was to document the effect of muscle fatigue on glenohumeral kinematics. Twelve male volunteers without shoulder disease and with an average age of 27 years were studied. Glenohumeral anteroposterior radiographs were taken at 45 degrees intervals as the arm was abducted in the plane of the scapula from 0 degree to 135 degrees. This series of radiographs was performed both before and immediately after the subject performed a series of deltoid and rotator cuff fatiguing exercises. The average humeral head position or translation before and after muscle fatigue for each arm angle was compared. For all subjects, before fatigue, the position of the humeral head was below the center of the glenoid for all angles of abduction. There was essentially no change in position of the humeral head in the prefatigue state, as the arm was abducted from 0 degree to 135 degrees with no more than an average 0.3 mm of total humeral head excursion. After fatigue, excursion of the humeral head increased to an average of 2.5 mm between the tested positions. The position of the humeral head with the arm at 0 degree of abduction was lower or had migrated inferiorly compared with the rested state, with an average 1.2 mm significant increase in inferior translation. With the initiation of abduction, the humeral head demonstrated significant superior migration or translation in all positions tested. This result has important implications for conservative treatment of shoulder impingement and underscores the importance of rehabilitation to maximize the endurance and strength of the rotator cuff musculature.

The retrograde medullary superior pubic ramus screw for the treatment of anterior pelvic ring disruptions: A new technique

Summary: Retrograde medullary screws were used in 26 patients with unstable pelvic ring injuries to stabilize the superior pubic ramus fractures. The posterior pelvic ring fractures and dislocations were fixed with iliosacral screws. The retrograde screws were inserted after closed manipulative reductions of the superior pubic ramus fractures in 15 patients and after open reduction in nine patients. We were unable to insert the screw in two patients due to anatomical variations. One screw was misplaced superior to the pubic ramus and noted only on the postoperative computed tomography scan. Another patient experienced symptomatic screw disengagement that required reoperation. All fractures healed and no infections developed. Blood loss was minimal for the percutaneous procedures. The technique provides stability to the anterior pelvic ring without the need for extensile surgical exposures. The complications of both anterior pelvic external fixation and plating are avoided, yet this technique has its own potential problems. The procedure is described in detail, and the early results and complications are documented in our first 26 patients

Contact Pressures at Osteochondral Donor Sites in the Knee

The purposes of this study were to determine whether any of the commonly recommended osteochondral donor sites are nonarticulating throughout a functional range of knee motion, and to determine the differential contact pressures for these sites. Ten commonly recommended sites for osteochondral harvest were evaluated with pressure-sensitive film through a functional range of motion with a model that simulated nonweightbearing resistive extension of the knee. All 10 donor sites demonstrated a significant contact pressure through 0° to 110° of knee motion. The different color density measurements between donor sites were also significant. Although donor sites 1, 2, 9, and 10 demonstrated significantly less contact pressure than the sites with the greatest contact pressure, the difference in mean pressures was small. No osteochondral donor site tested was free from contact pressure. It is currently unknown whether articular contact at these osteochondral donor sites will lead to degenerative changes or any other problems.

Arthroscopic meniscal repair with fibrin clot of complete radial tears of the lateral meniscus in the avascular zone

Peripheral lateral meniscal tears are amenable to arthroscopic meniscal repair. However, the posterolateral aspect of the lateral meniscus adjacent to the popliteus tendon is devoid of penetrating peripheral vessels and therefore difficult to heal. A complete radial split at this site is usually treated with total meniscectomy. We report five cases of a tear of the posterolateral aspect of the lateral meniscus anterior to the popliteus fossa. All patients had a radial split that extended to the popliteus tendon. In all cases, the repair was enhanced with a fibrin clot. Second-look arthroscopy showed that healing of the periphery occurred in all of the cases. All patients returned to their initial level of sports activity. Three of five patients were available for follow-up at an average of 71 months, and magnetic resonance imaging was performed at that time to assess the previously repaired meniscus. All menisci were fully healed and showed no further signs of degeneration. The ability of an exogenous fibrin clot to stimulate and support a reparative response in the avascular portion of the meniscus may represent a potential method of repair. Awareness of the relatively low healing potential of this zone and enhancement of healing opportunities should improve outcome.

Different regional healing rates with the outside-in technique for meniscal repair

Fifty-one patients with meniscal repair using the outside-in technique were reassessed with second-look arthroscopic procedures (N 15), arthrographic examination (N 41), magnetic resonance imaging (N 36), or a combination of these techniques. Forty-one medial and 10 lateral menisci were repaired. The average clinical follow-up was 15 months (range, 3 to 80). Forty-five of 51 patients had tears that were located in or extended into the posterior horn of the medial or lateral meniscus. Complete healing occurred in 23 menisci (45%), partial healing was observed in 16 (15 medial, 1 lateral) (32%), and no healing occurred in 12 (24%). Remarkably, in all 15 patients who had tears extending from the posterior to the middle third of the medial meniscus that were partially healed, it was always the posterior third that had not fully healed. This finding is statistically significant. In addition, the middle third of these menisci had not fully healed in five patients. No healing occurred in the two patients with tears in the posterior third of the medial meniscus. Poor healing with the outside-in technique was observed in patients with tears into the posterior horn of the medial meniscus. For tears in the middle and anterior portion of the medial meniscus, as well as all lateral meniscus tears, the outside-in technique is our current method of choice.

STABILIZATION OF PELVIC RING DISRUPTIONS

Pelvic ring disruptions are challenging management problems for the orthopedic surgeon. Early hemorrhage, permanent nerve injury, and late pain caused by residual pelvic deformity are some of the many complicating factors. A variety of treatment alternatives are available to stabilize the disrupted pelvic ring. Each technique has inherent advantages and problems.

Internal fixation of the unstable anterior pelvic ring: a biomechanical comparison of standard plating techniques and the retrograde medullary superior pubic ramus screw.

Summary: The purpose of this study was to evaluate pubic ramus fracture fixation. This biomechanical evaluation compared standard plating techniques with retrograde medullary screw fixation of a superior pubic ramus fracture in a pelvic fracture model. Six fresh-frozen, cadaveric pelvic specimens with a mean age of 79 years were harvested. These specimens were physiologically loaded according to the following modifications and instrumentations: (a) intact; (b) an APC-II unstable pelvic injury, specifically, unilateral superior and inferior rami osteotomies combined with ipsilateral anterior sacroiliac (SI) joint, sacrospinous, and sacrotuberous ligamentous disruptions, without fixation; (c) disrupted as in (b) but fixed anteriorly with a 10-hole 3.5-mm reconstruction plate contoured to the superior ramus and secured with four 3.5-mm cortical screws; (d) disrupted as in (b) but fixed anteriorly with a 10-hole 3.5-mm reconstruction plate contoured to the superior ramus and secured with six 3.5-mm cortical screws; (e) disrupted as in (b) but fixed anteriorly with a 4.5-mm retrograde medullary superior pubic ramus cortical screw 80 mm long (medial to the hip joint); and (f) disrupted as in (b) but fixed anteriorly with a 4.5-mm retrograde medullary superior pubic ramus cortical screw 130 mm long that was extraarticular and engaged the lateral iliac cortex cephalad to the ipsilateral hip joint. The posterior disruptions of the pelvic ring were not fixed. The APC-II injury created in this study resulted in significant (p < 0.05) motion at the disrupted rami and the injured SI joint, compared with the intact pelvic specimen. When compared with the disrupted specimen without fixation, displacement at the superior ramus was significantly (p < 0.05) decreased by all forms of ramus fixation evaluated. Plate fixation decreased pubic ramus and sacroiliac deflections slightly better than retrograde screw fixation did, yet not significantly better. The number of screws in the plate did not significantly affect displacement measurements at either the disrupted ramus or the disrupted SI joint. Similarly, the length of the retrograde ramus screw did not significantly alter displacements at either the injured pubic ramus or the disrupted SI joint. Sacroiliac joint deflections were not significantly (p < 0.05) decreased by any of the forms of anterior pelvic fixation. Flexion at the disrupted SI joint was slightly, but not significantly (p < 0.05), decreased with all forms of fixation when compared with the disrupted specimen. The long retrograde screw and the plate with six screws decreased flexion slightly, but not significantly, better than the short retrograde screw and the plate with four screws.

Simple anterior pelvic external fixation

BACKGROUND Unstable pelvic ring disruptions are often associated with significant morbidity and mortality, especially in patients with multiple injuries. Early pelvic fixation provides stability and should diminish ongoing hemorrhage. A simple anterior single-pin pelvic external fixator can be applied rapidly and accurately to stabilize pelvic ring injuries as a part of the initial patient resuscitation of such patients. Simple anterior pelvic external fixation (SAPEF) frames can be used as either temporary, definitive, or supplementary fixation depending on the pelvic injury pattern. METHODS Over a 32-month period, 41 patients with unstable pelvic ring disruptions were stabilized using a simple anterior pelvic external fixator. Eight patients had open pelvic ring injuries and 13 others had genitourinary system disruptions. Fluoroscopic imaging was used to insert all of the fixation pins into the iliac crest between the iliac cortical tables to a depth of at least 5 cm. Each patient had closed manipulative reduction of the pelvic ring using external methods before SAPEF application. RESULTS One patient died less than 24 hours after injury because of torrential hemorrhage. Clinical evaluations and serial radiographs, including postoperative computed tomographic scans, were available for the other 40 patients postoperatively. Seventy-five of the 80 (94%) pins were completely contained between the iliac cortical tables, according to the computed tomographic scans. The initial pelvic closed reductions were maintained until the fixators were removed in 37 of 40 patients (93%). Only one deep pin track infection developed, mandating early frame removal and intravenous antibiotic therapy. CONCLUSION Simple anterior pelvic external fixation can be applied rapidly using fluoroscopic guidance to direct accurate pin insertion and closed manipulative reduction of the pelvis. Depending on the specific pelvic ring injury pattern and clinical scenario, SAPEF can serve as a resuscitative temporary fixation device, as definitive pelvic treatment, or as a supplement for pelvic internal fixation implants.