Five-Strand Hamstring Grafts are Biomechanically Comparable to Four-Strand Grafts and Offer Greater Diameter for Anterior Cruciate Ligament Reconstruction.

Purpose: The purpose of this study was to compare the biomechanics of 4-strand and 5-strand hamstring constructs for anterior cruciate ligament grafts. Methods: Thirty-six human cadaveric hamstring grafts were tested in 3 different conditions: (1) graft femoral fixation complex, (2) graft femoral and tibial fixation (GFTF) complex using a human model, and (3) GFTF complex using a porcine model. Grafts were tested on a tensile testing machine. Four-stranded grafts served as the control group, and 5-stranded grafts served as the experimental group. Cyclic elongation, ultimate load to failure, stiffness, and diameter of the grafts were analyzed. Results: Average 4-strand graft diameter was 7.96 mm compared to 9.32 mm for the 5-strand graft (P = .00017). Average stiffness of grafts ≥8 mm was 105.04 N/mm compared to 85.05 N/mm for grafts <8 mm (P = .04988). There was a positive correlation between graft diameter and stiffness (13.4 N/mm per every 1 mm increase in diameter, r 2 value of 13.1%, and F-significance of 0.02778). There were no significant differences in terms of ultimate load to failure, cyclic elongation, or stiffness between the experimental groups. Conclusion: Five-strand hamstring grafts offer greater diameter and are biomechanically comparable to 4-strand equivalents at time 0. Grafts >8 mm offer significantly greater stiffness compared to grafts sized <8 mm. There is a weak positive correlation between graft diameter and stiffness. Clinical Relevance: A potential drawback to hamstring grafts is their variability in size. Five-strand hamstring grafts provide increased diameter in comparison to 4-strand equivalents and might be used when quadrupled graft diameter is <8 mm.

Biomechanical Comparison of Meniscal Allograft Root Fixation Techniques: Anterograde Interference Bone Plug Fixation Yields Favorable Results Compared to Transosseous Suture Fixation Alone.

Purpose: To compare the biomechanical properties of 2 different fixation techniques (interference bone plug fixation vs transosseous suture fixation) of the posterior horn of the medial meniscus using a porcine model. Methods: Twenty-six matched pairs of fresh-frozen juvenile domestic porcine knees were used in this study. Specimens were randomly distributed among 3 groups: (1) native meniscus groups, (2) interference fixation, and (3) transosseous suture fixation. In each group, the posterior segments of the tested medial menisci were gripped with the freeze clamps and fixed to the tensile testing machine. Samples were preconditioned, followed by cyclic tension-relaxation for 1000 cycles between 10 and 30 N at 0.5 Hz and finally pulled to failure at a rate of 0.55 mm/s. The cyclic elongation, stiffness to failure, mode, and ultimate load to failure were recorded. Results: There was no significant difference in ultimate load to failure between the interference fixation (169.71 ± 71.98 N) and transosseous suture fixation (222.73 ± 72.40 N) groups (P = .118), both were significantly less than that of the native meniscus (405.46 ± 95.62) (P < .001). Interference fixation displayed cyclic elongation (1.04 ± 0.71 mm) and stiffness (69.10 ± 25.8 N/mm) that were not significantly different from the native meniscus tissue (0.78 ± 0.53 mm and 83.1 ±26.28 N/mm) (P = .359 and P = .224), in comparison to transosseous suture fixation, which did show increased cyclic elongation (1.85 ± 1.44 mm) (P = .047) and decreased stiffness (34.72 ± 10.2 N/mm) (P < .001). Conclusion: Interference fixation of the posterior horn of the medial meniscus has superior cyclic elongation and stiffness when compared to transosseous suture fixation. Interference fixation and the native meniscus model have a similar stiffness and cyclic elongation. Clinical Relevance: The significance of our study is that using interference fixation for meniscal allograft transplantation has the potential to reduce short term surgical failures as well as long term complication rates.

The changing causes of graft loss and death after kidney transplantation.

BACKGROUND: The results of kidney transplantation have improved markedly over the last three decades. Despite this, patients still lose grafts and die. We sought to determine whether the causes of graft loss and death have changed over the last 30 years. METHODS: We reviewed patients who underwent transplantation or who died between January 1, 1970 and December 31, 1999. We compared the causes of graft loss or death for three decades: 1970 to 1979, 1980 to 1989, and 1990 to 1999. RESULTS: From January 1, 1970 to December 31, 1999, we performed 2501 kidney transplantations in 2225 patients. For the three periods, 210, 588, and 383 patients lost their grafts, respectively. Graft survival increased substantially. Graft loss occurred later after transplantation, with 36.0% losing grafts in the first year during 1970 to 1970, 22.8% during 1980 to 1989, and 11.4% during 1990 to 1999. Death with a functioning graft increased from 23.8% for 1970 to 1979 to 37.5% for 1990 to 1999. Concomitantly, rejection as a cause of graft loss fell from 65.7% for 1970 to 1979 to 44.6% for 1990 to 1999. Approximately two thirds of the patients who died after transplantation died with a functioning graft and one third died after returning to dialysis. Cardiac disease as a cause of death increased from 9.6% for 1970 to 1979 to 30.3% for 1990 to 1999. Deaths from cancer and stroke also increased significantly over the three decades from 1.2% and 2.4%, respectively, for 1970 to 1979, to 13.2% and 8.0%, respectively, for 1990 to 1999. CONCLUSIONS: The causes of graft loss and death have changed over the last three decades. By better addressing the main causes of death, cardiac disease, and stroke with better prevention, graft loss due to death with a functioning graft will be reduced.

Return to play criteria for the athlete with cervical spine injuries resulting in stinger and transient quadriplegia/paresis.

BACKGROUND CONTEXT: Fortunately, catastrophic cervical spinal cord injuries are relatively uncommon during athletic participation. Stinger and transient quadriplegia/paresis are more frequent injuries that have a wide spectrum of clinical severity and disabilities. Although the diagnosis of these injuries may not be clinically difficult, the treatment and decision about when or if the athlete may return to play after such an injury is often unclear. PURPOSE: This article reviews the current literature to help determine reasonable guidelines for return-to-play criteria after cervical spine injuries in the athlete. METHODS: The contemporary English literature and experience-based guidelines for return to play after cervical spine injuries in the athlete were reviewed. RESULTS: Despite the frequency of cervical-related injuries among athletes participating in contact and collision sports, no consensus exists within the medical field as to a standard guideline approach for return to preinjury activity level. CONCLUSION: The issue of return to play for an athlete after a cervical spine injury is controversial. Tremendous extrinsic pressures may be exerted on the physician from noninvolved and involved parties. The decision to return an athlete to a particular sport should be based on the mechanism of injury, objective anatomical injury (as demonstrated by clinical examination and radiographic evaluation) and an athlete's recovery response.