Michael Wettstein

Traumatic Rupture of Both Peroneal Longus and Brevis Tendons

Injuries of peroneal tendons are rare. Diagnosis of traumatic rupture is often late and presents as chronic ankle instability. A case of a complete traumatic rupture of both peroneal longus and brevis tendons with acute clinical and radiological diagnosis is presented. Surgical repair was performed by direct end-to-end suture on the 4th day after trauma, with excellent functional outcome at 1-year follow-up.

Three-dimensional computed cementless custom femoral stems in young patients : Midterm followup

We prospectively evaluated the results of our custom cementless femoral stems to ascertain whether this technology produced reasonable clinical function, complication rates, and loosening rates at midterm. Fifty-seven consecutive patients had surgery in 62 hips for primary osteoarthritis at a mean age of 57 years using a three-dimensional computed custom cementless stem. Patients were reviewed at a mean followup of 94.9 months. At review, the mean Harris hip score was 98.8 points (range, 84-100) compared with 61.1 (range, 28-78) points preoperatively. No patient complained of thigh pain. No migration or subsidence was observed. All stems were considered stable according to the radiographic criteria defined by Engh et al. There were no dislocations, no infections, and no reoperations. Our results are comparable with published results from clinical and radiologic points of view. Two problems remain unsolved: the price of a custom stem is twice as expensive as a standard stem; and we need longer term results before definitely recommending this technology as a reasonable alternative to current arthroplasties in younger patients. The data support the continued exploration of this technology with controlled clinical followup. Level of Evidence: Therapeutic study, Level II-1 (prospective cohort study). See the Guidelines to Authors for a complete description of levels of evidence.

Anterior subluxation after reduction of a posterior traumatic sterno-clavicular dislocation: a case report and a review of the literature

Sternoclavicular dislocations represent a rare injury. Based on our clinical experience with a patient showing an anterior subluxation after reduction of a posterior traumatic dislocation, we review the literature. The emergent reduction of the dislocation is mandatory, always keeping in mind the potentially devastating neurovascular complications. If the treatment of a residual anterior instability remains controversial, a residual posterior instability should be treated by a surgical procedure. The optimal treatment depends mainly on each surgeon’s choice and practice.

Simultaneous and multisite measure of micromotion, subsidence and gap to evaluate femoral stem stability

The initial stability of cementless femoral components is crucial for the long-term success of total hip arthroplasty. This has been reported in animal and clinical studies. Until now, the stability was evaluated by the measurement of relative micromotion on a few simultaneous locations around the stem in cadaveric experiments. This paper presents an extended experimental setup to measure simultaneously local micromotion, subsidence and gap on hundreds of points at the bone-stem interface. This technique we applied to anatomical and straight stems in three pairs of cadaveric femurs. Measurements were in agreement with typically reported values. Conversely to other methods, which measure micromotion between implant and bone anchoring points of the measuring device, our method provides local micromotion between stem surface and adjacent bone surface. The observed variation of micromotion at the peri-implant surface confirms the importance of this simultaneous measure on a lot of points around the implant.

A new technique to measure micromotion distribution around a cementless femoral stem

The interfacial micromotion is closely associated to the long-term success of cementless hip prostheses. Various techniques have been proposed to measure them, but only a few number of points over the stem surface can be measured simultaneously. In this paper, we propose a new technique based on micro-Computer Tomography (μCT) to measure locally the relative interfacial micromotions between the metallic stem and the surrounding femoral bone. Tantalum beads were stuck at the stem surface and spread at the endosteal surface. Relative micromotions between the stem and the endosteal bone surfaces were measured at different loading amplitudes. The estimated error was 10 μm and the maximal micromotion was 60 μm, in the loading direction, at 1400 N. This pilot study provided a local measurement of the micromotions in the 3 direction and at 8 locations on the stem surface simultaneously. This technique could be easily extended to higher loads and a much larger number of points, covering the entire stem surface and providing a quasi-continuous distribution of the 3D interfacial micromotions around the stem. The new measurement method would be very useful to compare the induced micromotions of different stem designs and to optimize the primary stability of cementless total hip arthroplasty.

Operative Compared with Nonoperative Treatment of a Thoracolumbar Burst Fracture without Neurological Deficit

To The Editor: We read with interest the article entitled “Operative Compared with Nonoperative Treatment of a Thoracolumbar Burst Fracture without Neurological Deficit. A Prospective, Randomized Study” (2003; 85:773-81), by Wood et al. The authors speak about “stable” burst fractures of the thoracolumbar junction. The inclusion criteria included the absence of a posterior column lesion (except for a laminar fracture, which was neither an exclusionary criterion nor a contraindication for nonoperative treatment). The first definition categorizes the fractures as burst type-A3 fractures according to the AO classification system1, which is widely used. A laminar fracture, however, indicates a posterior column lesion, thereby categorizing the fracture as type B1 according to the AO classification1. According to the criteria described by Denis2 and Louis and Goutallier3, a type-A3 burst fracture, by definition, represents an unstable lesion as two of three columns are involved and a type-B1 fracture represents a highly unstable lesion as three columns are involved. Therefore, we think that it is incorrect to speak about a “stable” burst fracture. Furthermore, we fear that comparing operative treatment with nonoperative treatment on the basis of the follow-up data for forty-seven (89%) of fifty-three patients is misleading. We do not believe that it is advisable to test for significant differences between two small groups of patients because of the possibility of inducing … Corresponding author: Kirkham B. Wood, MD Massachusetts General Hospital 15 Parkman Street Wang Ambulatory Center Suite 503 Boston, MA 02114 kbwood{at}partners.org

Measuring micromotion around a loaded hip stem using μCT imaging

It has been established that primary stability of femoral stems is a determinant of the clinical success of cementless total hip arthroplasty (Kobayashi et al. 1997). Excessive interface micromotions may lead to a peri-implant fibrous tissue formation resulting in aseptic loosening of the implant (Soballe et al. 1993). The effect of micromotion on the tissues still remains unclear. However, it is becoming increasingly clear that interstitial fluid flow is the primary mechanism by which bone cells perceive changes in their mechanical environment (Riddle et al. 2009). Therefore, to estimate the interstitial peri-implant fluid flow, a detailed measurement of simultaneously normal and tangential micromotion is required. The objective of this study is to assess the feasibility of the micromotion measurement on human cadaveric femur with micro-computed tomography (mCT).