Open Access Highly Accessed Open Badges Study protocol

Resorbable screws versus pins for optimal transplant fixation (SPOT) in anterior cruciate ligament replacement with autologous hamstring grafts: rationale and design of a randomized, controlled, patient and investigator blinded trial [ISRCTN17384369]

Dirk Stengel123*, Gerrit Matthes12, Julia Seifert1, Volker Tober1, Sven Mutze4, Grit Rademacher4, Axel Ekkernkamp12, Kai Bauwens12, Michael Wich1, Dirk Casper1 and the SPOT Group

Author Affiliations

1 Department of Orthopaedic and Trauma Surgery, Unfallkrankenhaus Berlin Trauma Center, Warener Str 7, 12683 Berlin, Germany

2 Department of Orthopaedic and Trauma Surgery, Sauerbruchstr., University Hospital of Greifswald, 17487 Greifswald, Germany

3 Department of Clinical Epidemiology, Unfallkrankenhaus Berlin Trauma Center, Warener Str 7, 12683 Berlin, Germany

4 Institute of Radiology, Unfallkrankenhaus Berlin Trauma Center, Warener Str 7, 12683 Berlin, Germany

For all author emails, please log on.

BMC Surgery 2005, 5:1  doi:10.1186/1471-2482-5-1

Published: 21 February 2005



Ruptures of the anterior cruciate ligament (ACL) are common injuries to the knee joint. Arthroscopic ACL replacement by autologous tendon grafts has established itself as a standard of care.

Data from both experimental and observational studies suggest that surgical reconstruction does not fully restore knee stability. Persisting anterior laxity may lead to recurrent episodes of giving-way and cartilage damage. This might at least in part depend on the method of graft fixation in the bony tunnels. Whereas resorbable screws are easy to handle, pins may better preserve graft tension. The objective of this study is to determine whether pinning of ACL grafts reduces residual anterior laxity six months after surgery as compared to screw fixation.

Design/ Methods

SPOT is a randomised, controlled, patient and investigator blinded trial conducted at a single academic institution. Eligible patients are scheduled to arthroscopic ACL repair with triple-stranded hamstring grafts, conducted by a single, experienced surgeon. Intraoperatively, subjects willing to engage in this study will be randomised to transplant tethering with either resorbable screws or resorbable pins. No other changes apply to locally established treatment protocols. Patients and clinical investigators will remain blinded to the assigned fixation method until the six-month follow-up examination.

The primary outcome is the side-to-side (repaired to healthy knee) difference in anterior translation as measured by the KT-1000 arthrometer at a defined load (89 N) six months after surgery. A sample size of 54 patients will yield a power of 80% to detect a difference of 1.0 mm ± standard deviation 1.2 mm at a two-sided alpha of 5% with a t-test for independent samples.

Secondary outcomes (generic and disease-specific measures of quality of life, magnetic resonance imaging morphology of transplants and devices) will be handled in an exploratory fashion.


SPOT aims at showing a reduction in anterior knee laxity after fixing ACL grafts by pins compared to screws.