Background: Quality control has found an important application in assessing learning curves of trainees and controlling innovative technologies as they are initiated.

Objective: To develop a quantitative and individualized statistical tool that may help trainees and tutors to define when a procedure is adequately learned and supervision may be safely stopped.

Methods: A series of 78 consecutive computer assisted-based navigation total knee replacements in patients with osteoarthritis or rheumatoid arthritis was monitored to control surgical performance. The primary outcome was limb alignment in the frontal plane. The target for alignment was 180° and the standard deviation for limb alignment for this series was 2.35°. Knees implanted with a deviation of more than 3 degrees from the target value were considered as failures. A new statistical tool, the CUSUM for Learning Curve (LC-CUSUM) was used to monitor surgical performance. The LC-CUSUM was developed to test whether a process has reached a predefined level of performance. Therefore, the LC-CUSUM presumes the process is not controlled (not learned) at the start of monitoring and the test will signal when the process can be considered as in-control (learned). For continuous data, two LC-CUSUMs are drawn simultaneously.

Results: The first 20 prostheses were more often implanted in varus alignment. Subsequently, the surgeon tried to correct this problem but tended to implant the prostheses more in valgus alignment (overcorrection). After a few more procedures the surgeon found a balance, and the implants were positioned around the target value with no apparent tendency to favour one side or the other. The positive LC-CUSUM signalled first at the fifth procedure; however, the negative LC-CUSUM had not crossed the lower limit and the surgeon could not be deemed as having achieved the required level of performance. It is not until the 25th procedures that the negative LC-CUSUM crossed the lower boundary. At this point, enough evidence had accumulated to state that the surgeon had reached proficiency. A standard CUSUM was initiated to monitor the process to the end and ensure it would not deviate from the required performance. After the seventy-eighth procedure, monitoring was discontinued.

Conclusion: The LC-CUSUM is an innovative tool that allows quantitative monitoring of individual surgical performance during learning process. It allows stating when a predefined acceptable level of performance is reached.

Purpose: Surgical techniques must be evaluated before proceeding with widespread use. The evaluation system is usually copied after that used for drugs, relying on randomised trials. This system fails however to assess one dimension, i.e. quality control. The purpose of the present study was to demonstrate the usefulness of an evaluation technique taking into account the capacity to control the quality of a surgical procedure and determine the reliability, reproducibility, and controllability of the technique. This method of evaluation was applied to computer-assisted surgery for total knee arthroplasty.

Material and methods: Computer-assisted surgery based on 3D bone reconstruction was used for 78 knees. The main outcome assessment criterion was the mechanical axis from the centre of the femoral head to the centre of the ankle. The desired alignment was between 3° varus and 3° valgus. Alignments were measured continuously by an independent operator. A Cusum curve was drawn over time and tested after each operation to determine whether the procedure under evaluation could be continued. The same method was applied to the position of the individual femoral and tibial implants setting the limits at two degrees around the perpendicular mechanical axis (AP view).

Results: The mechanical axis was between 3° varus and 3° valgus in 91% of the knees. The continuous evaluation curve showed that the procedure was under control throughout the trial. There was a learning curve that plateaued at 27 knees. Evaluation of the position of the individual implants showed a trend towards femur valgus over time which was compensated by a trend towards tibial varus.

Discussion: Industrial quality control procedures are well established and widely used. The goal of this work was to apply the same quality control methodology to a surgical procedure. Before undertaking a randomised trial this type of evaluation can affirm that the procedure is well controlled and that using an innovating technique under these conditions does not expose patients to undue risks.

Purpose: Appropriate management of complex trauma of the upper limb (CTUL) is a significant therapeutic challenge. The main difficulty is to determine in an emergency situation when ambitious conservative surgery is legitimate and when amputation in necessary. We propose a prognostic lesion score to determine the best option in the emergency setting.

Material and methods: This study included 48 patients operated on between 1987 and 1997. These patients presented total or partial amputation (n=23), devascularising injury with continuous limb (=7), complex non-devascularising injury with continuous limb (n=18) (Gustilo IIIa and IIIb). Isolated hand trauma was excluded. Each patient was attributed retrospectively a lesion score taking into account each tissue (bone, vessels, nerves, muscles, skin). At minimum two-year follow-up, the outcome was evaluated for the amputated or non-amputated limb. For each non-amputated patient, a more precise outcome was established using the Chen classification. Operative procedures used the same protocol for all patients.

Results: Considering the functional results, the statistical analysis enabled identifying prognostic factors for amputation among the five variables studied. Analysis using a classification tree enabled development of a decisional algorithm based on the muscle, nerve and skin injuries which provided 64.7% sensitivity and 100% specificity with a 100% positive predictive value and an 83.8% negative predictive value. A multiple logistic model was used to confirm these results and led to the selection of the same variables.

Discussion: The CTUL score is easy to use and is the only one in the literature using only variables statistically proven to have significant prognostic value for CTUL. Surgical experience is however indispensable for appropriate decision making in these emergency situations. This score thus provides an important therapeutic aid useful in borderline cases where amputation is discussed.

Conclusion: A prospective study including a larger number of patients would be helpful to better detail indications and preserve the 100% specificity for an irreversible therapeutic decision.

We have carried out a prospective, randomised study designed to compare the long-term stability of the stem of cementless femoral implants with differing surface configurations. A total of 50 hips (46 patients) was randomised into two groups, according to whether the medullary stem had been grit blasted (GB) or coated with hydroxyapatite (HA). Both femoral prostheses were of the same geometrical design. We used Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA) to assess the stability of the stem. The mean follow-up was for 8.66 years.

The mean migration of the stem was 1.26 mm in the HA group compared with 2.57 mm in the GB group (Mann-Whitney U test, p = 0.04). A mixed model ANOVA showed that the development of subsidence was statistically different in the two groups during the first 24 months. After this subsidence increased in both groups with no difference between them. Our results indicate that, with the same design of stem, HA coating enhanced the stability of the femoral stem when compared with GB stems.