Failure properties of suture anchors in the glenoid and the effects of cortical thickness.

The ultimate pullout strength and fatigue properties of a screw-design suture anchor implanted in the anterior glenoid rim were investigated and compared with results from a nonscrew-design suture anchor. Twenty-two cadaveric glenoids were harvested and one to two anchors were implanted in the superior and inferior quadrants. Fifty-seven Statak 3.5 anchors (Zimmer, Warsaw, IN) were tested and compared with results obtained in a previous study on 50 Mitek GII anchors (Mitek Products, Inc, Westwood, MA). The specimens were mounted on an Instron fatigue testing machine (Instron Corp, Canton, MA) and cycled between preselected minimum and maximum loads until pullout. The Mitek GII maintained a higher pullout strength than the Statak 3.5 after cyclic loading. Cortical thickness at the implantation sites was measured, and found to decrease monotonically from superior to inferior positions. The ultimate pullout strength, and subsequently the fatigue life, of both types of suture anchors depended directly on cortical thickness. The significantly lower performance of both anchors when placed inferiorly emphasizes the importance of correct anchor selection, number, and placement in this region. All anchors settled during the first 10 to 100 cycles, resulting in partial exposure of the implant. Intraoperative cycling of the anchors before suture tying may be necessary to achieve complete settling and prevent subsequent loss of coaptation between capsule and glenoid. The study shows that for the anchors to last 1,000 cycles or more, less than 50% of the theoretical ultimate pullout strength should be applied cyclically. With aggressive early rehabilitation exercises, this significant decrease in fixation strength could shift reconstruction failure from suture breakage or soft tissue tearing to anchor pullout.

Occurrence of cervical spine injuries during the rugby scrum.

A retrospective study of cervical spine injuries that occurred during the rugby scrum in the United States was undertaken. In the U.S., from 1970 to 1996, 36 (58%) of the 62 documented injured players injured their cervical spines during the scrum. Thirty-five men (97%) and one woman (3%) were injured. Twenty-three of the injuries (64%) occurred when the opposing packs came together (engagement), and 13 (36%) occurred when the scrum collapsed. Twenty-eight (78%) hookers, seven (19%) props, and one (3%) second-row player were injured. Twenty (56%) hookers and three (8%) props were hurt during engagement. Eight hookers (22%), four props (11%), and one second-row player (3%) were injured when the scrum collapsed. Significantly more injuries occurred during engagement than during collapse, and hookers were injured significantly more than props. We conclude that in the rugby scrum in the U.S., the hooker suffers most of the cervical spine injuries (78% in this study) and this position is by far the most vulnerable. This study should be used to develop rugby law (rule) changes and educate players, coaches, and referees in United States rugby.

Knee injuries in women collegiate rugby players.

We evaluated the prevalence and patterns of knee injuries in 810 women collegiate rugby players. Injuries that resulted in players missing at least one game were recorded and a questionnaire was used to delineate players' rugby and knee injury history. There were 76 total knee injuries in 58,296 exposures. This resulted in a 1.3 knee injury rate per 1000 exposures. Twenty-one anterior cruciate ligament tears were reported for a 0.36 incidence per 1000 exposures. Other injuries included meniscal tears (25), medical collateral ligament sprains (23), patellar dislocations (5), and posterior cruciate ligament tears (2). Sixty-one percent of the medial collateral ligament sprains occurred in rugby forwards and 67% of anterior cruciate ligament tears occurred in rugby backs. All other injuries occurred with equal frequency in backs and forwards. This study demonstrates that knee injury rates in women's collegiate rugby are similar to those reported for other women's collegiate sports. The overall rate of anterior cruciate ligament injury in women's rugby, however, is slightly higher than that reported for women soccer and basketball players.

Fatigue properties of suture anchors in anterior shoulder reconstructions: Mitek GII.

Suture anchors have simplified anterior capsule labral reconstruction. During rehabilitation the shoulder goes through many repetitions of range of motion exercises. These exercises will repetitively submaximally load the anchor and in theory should reduce the pullout strength of the suture anchor. No published reports exist on the fatigue strengths and properties of one of the most commonly used anchors: Mitek GII suture anchors. Fifty trials of cyclic submaximal load were done on 22 cadaveric glenoids with an average age of 66.8 years (range, 40 to 90 years). At two to three different sites on the same specimen, the anchors were inserted according to manufacturer's specifications. The anchors were tested to failure on a Instron 1331 servohydraulic mechanical testing system at 2 Hertz sinusoidal loading pattern using steel sutures and a predetermined load. There were 22 (44%) tests performed in the superior quadrant and 28 (56%) tests in the inferior quadrant. All anchors pulled out, and no wires broke. There were statistically significant differences between the superior and inferior portion of the glenoid with regard to number of cycles to failure at a given maximum load. The anchors underwent an average of 6,220 cycles before pullout at an average load of 162 N (SD = 73 N). In the superior quadrant, the average ultimate pullout strength was 237 N (SD = 42 N), whereas in the inferior quadrant the average ultimate pullout strength was 126 N (SD = 36 N). Hence, the ultimate pullout strength of the Mitek GII anchor was significantly higher (P < .002) in the superior quadrant than in the inferior quadrant. Using a least squares regression analysis, it was possible to predict the fatigue life of the superiorly and inferiorly placed suture anchors over a wide range of cycles. The R-squared values for trendlines showed good reliability (superior R2 = 0.55; inferior R2 = 0.28). The fatigue life curves for the two different quadrants were normalized using the ultimate pullout strength. This new, universal curve predicts the fatigue life of the Mitek GII anchor as a percentage of the ultimate pullout strength for any selected location. For a clinically relevant number of cycles, no more than approximately 40% to 50% of the ultimate pullout strength of the suture anchor can be cyclically applied to the anchor to guarantee a life for the duration of rehabilitation. For the entire system, the inferiorly placed anchors dictate the amount of cyclically applied load the system can experience without failing, and rehabilitation should be adjusted accordingly.

A retrospective study of cervical spine injuries in American rugby, 1970 to 1994.

We undertook a retrospective study to document and analyze the occurrence of cervical spinal injuries in rugby in the United States from 1970 to 1994. We studied 59 cases (average, 2.36 per year). Thirty junior-level players (50.8%) (college or high school), 28 (47.5%) men's club players, and 1 (1.7%) woman player were injured. Fifty-seven injuries (97%) occurred during games. The incidence of cervical spine injuries is well documented in the United Kingdom and South African literature. However, no study in United States literature discusses the incidence or cause of cervical spine injury in rugby. We found that coaching is less consistent in the United States. Players with more weight and less experience are playing positions that require significant skill. Many players in the United States learn skills in games rather than in practice. In our study, 52.5% (31 of 59) of the injured players were junior-level players. Conversely, in world competition junior-level athletes sustained only 30% to 40% of the cervical spine injuries. Understanding the factors that contribute to cervical spine injuries is paramount in injury prevention. Through this study, we hope to promote change in rugby laws and regulations, as has been done in football, to enhance the safety and pleasure of the sport for players, coaches, and spectators.

Early weight bearing of lateral tibial plateau fractures.

From 1975 to 1984, 134 consecutive lateral tibial plateau fractures were treated as part of this prospective study. Eighty-six fractures (64%) were followed until union, with an average follow-up period of 22.7 months. The two aims of this study were: First, to analyze the results of operative and nonoperative therapy in each fracture type, and second, to evaluate the effect of early weight bearing in a cast brace in both types of treatment. All lateral tibial plateau fractures with greater than 5 mm depression or displacement were treated operatively. Forty-four patients were treated operatively and 42 patients nonoperatively. All patients were treated with early range of motion and weight bearing in a cast brace. Fractures were initially classified using Hohl's classification system. Overall, 95% of the patients with Type I, II, or V fractures had satisfactory results, as opposed to only 70% of patients with Type III fractures. Of the Type III fractures, 83% treated operatively had satisfactory results compared with 53% treated nonoperatively. Moreover, early weight bearing did not produce further depression greater than 2 mm.

Treatment of open tibial fractures with Ender rods.

In a retrospective, nonrandomized study from 1980 until 1988, 43 patients with 46 open tibial fractures were treated with Ender rods. The configuration of each fracture was classified using the Orthopaedic Trauma Association's (OTA) tibial fracture guidelines, and the extent of soft-tissue damage was graded using the Gustilo classification of open fractures. The OTA classification was further divided into stable, unstable, and highly unstable fracture configurations. Ender rods were placed immediately into 90% of fractures; and within one week of initial injury in the remainder. Follow-up evaluation of four patients (six fractures) could not be completed. The average time to union was 22.1 weeks, and there was a low incidence of complications. Otherwise there was a 40% incidence associated with early rod removal. Most complications occurred in those fractures that had extensive soft-tissue damage, and minimal or no inherent axial stability (unstable and highly unstable OTA classes). Except for the above-noted complications, Ender rods provide effective fixation for open tibial fractures with some degree of axial and rotational stability. In fractures with minimal or no inherent axial stability (OTA Classes IIIC, D; IVA, B), and in Grade IIIB or IIIC open tibial fractures, Ender rods have a higher incidence of complications and should be used with caution.

Treating gunshot femoral shaft fractures with immediate reamed intramedullary nailing.

Reamed intramedullary nailing was used within 36 hours of patient admission to treat 32 consecutive femoral shaft fractures caused by low-velocity gunshot wounds. The femoral shaft fracture was classified according to the AO system, and comminution was graded according to the classification of Winquest and Hansen. Patients were followed for an average of 14.7 months (range, 6 to 36 months), and the average time to union was 18.6 weeks. The average hospital stay was 7 days, which is approximately one half the average stay reported in the literature for treating this kind of injury with delayed nailing. The shorter hospital stay represents potential savings of up to $9,000 per patient. Immediate intramedullary rodding is a safe, effective, and economic option for the treatment of a femoral shaft fracture caused by a low-velocity gunshot wound. However, a lack of compliance with instructions concerning weight-bearing in this patient population needs to be taken into account when planning postoperative care.

The floating hip. Ipsilateral pelvic and femoral fractures.

A consecutive series is reported of 17 patients who underwent early surgical treatment for acetabular or unstable pelvic fractures associated with ipsilateral fractures of the femur. Treatment included external and internal fixation, and required careful consideration of the surgical approach and the positioning of the patient. The multiple injuries sustained by these patients required simultaneous procedures by several surgical teams. All the femoral fractures were internally fixed at the initial operation and eight patients had primary definitive treatment of all their other fractures as well. In nine patients the definitive treatment of their other fractures was delayed for an average of 11 days. There were no deaths, and no serious infections. The long-term morbidity resulted from the associated injuries and not from the pelvic or femoral fractures.

A pneumatic leg brace for the treatment of tibial stress fractures.

Forty-two competitive athletes with posterior medial pain in the lower one-half of the tibia were evaluated by plain roentgenograms and bone scans. Twenty stress fractures were diagnosed in 17 patients by plain roentgenograms or bone scans or both. The remaining 25 patients were diagnosed as having shin splints. All 42 patients subsequently had a pneumatic leg brace applied to the affected limb or limbs. The 17 patients with stress fractures were able to ambulate without pain and were allowed to resume light training in an average of one week. Their injuries were nontender to palpation. The patients were allowed to resume intensive training at an average of 3.7 weeks postinjury. Patients returned to competition at the preinjury level in an average of 5.3 weeks after application of the brace. The pneumatic leg brace allowed the athletes with tibial stress fractures to begin pain-free ambulation and rehabilitation, thus facilitating the maintenance of their cardiovascular fitness and permitting an early return to competition.

The role of Ender rodding in tibial fractures with an intact fibula.

Thirty-three patients with tibia fractures and intact fibula were studied to determine the efficacy of Ender rod fixation in preventing a varus deformity of the tibia. Twenty-one patients were treated nonoperatively with five (23.8%) developing a significant varus angulation (greater than five degrees). No varus malunions were noted in those patients treated with Ender rods. Those patients treated with Ender rods and early weight-bearing had a shorter average time to union than those treated nonoperatively. We therefore feel that Ender rod fixation is a viable treatment modality in tibia fractures with an intact fibula. In these fractures the use of Ender rods helps prevent significant varus malunion and allows early weight-bearing, thus permitting early mobilization of the traumatized patient.