Purpose of the study: Recent data in the literature regarding intra-articular deliver of analgesics during the postoperative period have been encouraging. Patients benefit from optimal analgesia and earlier mobilisation, shortening rehabilitation time and hospital stay and limiting complications. In light of these encouraging results, our institution developed a programme designed to address all postoperative situations associated with implantation of a total knee arthroplasty (TKA).

Material and methods: The programme combines pre-operative counselling and a postoperative programme for multimodal anaesthesia in addition to intra-articular analgesia for 24 hours and early mobilisation. We present here the results of this technique in patients undergoing first-intention TKA. We analysed information collected prospectively in all patients who had TKA from January to June 2008: 319 patients in six months. The operation was performed under peridural anaesthesia supplemented by intra-articular ropivacaine delivered by a catheter for 24 hours. Patients were mobilised, or verticalised, the day of surgery according to individual capacities. Data collected included: pain scores, date of the end of physical therapy, and data reviewed at six weeks.

Results: A cohort of 305 patients was analysed; 36% of patients were mobilised the day of the operation and 93% on day 2. The rate of urinary catheters was 12% and administration of intravenous fluids 10%. Physical therapists determined that 58% of patients could be discharged on 3 after surgery and 85% on day 5. Eighty-percent of patients were free of nausea or vomiting and had well controlled pain. Regarding function, mean range of motion was 85° at discharge with 31% of patients requiring physical therapy. At six weeks, mean range of motion was 95° and only 5% of patients had lost amplitude (reduction > 10° of range of motion) compared to discharge values. Mean scores on the Oxford questionnaire improved from 43 preoperatively to 26 six weeks postoperatively.

Discussion: This multidisciplinary approach guarantees excellent postoperative analgesia with early mobilisation and provides satisfactory results at six weeks. To this can be added the benefit of a lower rate of urinary catheters, administration of intravenous fluids, and physical therapy.

Purpose of the study: Rotation of the tibial implant is an important factor for the functional outcome of total knee arthroplasty (TKA). Any rotational malposition will cause eccentric loading of the plateau. Several techniques have been recommended to avoid malposition, but none has proven superior over the others in terms of reliability or reproductibility. The landmark used to establish rotation must meet two prerequisites: easy identification and reliable representation of the anatomic rotation of the proximal tibia. This study was conducted to compare seven different techniques for landmarking used for choosing the rotation of the tibial base in TKA.

Material and methods: An optoelectronic method was used to measure 50 tibia selected among a collection of 600 skeletons. A palper was used to locate 34 distinct landmarks and institute each reference system. The groups of anatomic points were reconstructed to form lines and plans depending on the comparisons to make: posterior condylar alignment (PCA), transversal alignment (TA), anterior condylar alignment (ACA), alignment of the anterior tibial tuberosity (ATT), the transmalleolar alignment (TMA), the line of the tibial crest (LTC) and a new line, the anterior distal line (ADL). The PCA was used as the reference.

Results: Intra-observer variation was determined in a preliminary study using ten consecutive measurements. The standard deviation was 0.5° with a distribution of 1.8°. Angle: mean [-:internal rotation; +external rotation], standard deviation: difference between the minimum and the maximum. TA: −5.13; 9.2; 38.03; ACA: −12.81; 6.7; 41.74; ATT: 68.72; 8.6; 58.46; TMA: −22.68; 11.6; 72.84; LTC: 67.56; 10.3; 46.11; ADL: 16.61; 13.2; 74.93.

Discussion: This study did not prove convincingly that any one of the tibial alignments was better than another; which demonstrates that use of a single reference is probably inappropriate to determine the rotational alignment of the tibial base for TKA. It was noted however that the anterior condylar line (mean external rotation 12.8°-SD< 7° relative to the PCA) could be pertinent for future research since this line is easily accessible and palpable, particularly during navigated surgery.

The recognition of the correct pattern and severity of deformity in knee osteoarthritis has important implications in its surgical management. Our unit routinely uses standing long leg films and computer navigation. However, these modalities are not widely available and most surgeons rely on clinical assessment and short films. Our experience is that clinical assessment can give the opposite impression of the true deformity pattern particularly among obese patients and there is evidence that short knee films are not reliable. Our study aims to compare clinical, radiographic and computer measurements of knee deformity, assess the influence of Body Mass Index and asses the relationship between coronal and flexion deformity.

We measured 52 consecutive knees prior to arthroplasty using clinical, long leg radiographs and computer navigation methods. Systematic clinical measurement was done with patient standing. Standing radiographs stored in a Picture Archiving System were measured by two independent observers. The senior surgeon performed computer measurement while applying axial load to the foot to simulate weight bearing.

Using long leg films as baseline, clinical and X-ray measurement had a mean error of 0.8° (−12 to +12). Seven clinically valgus knees turned out varus on X-ray. Mean BMI for this group was the same as the rest. Using navigation as baseline, clinical and navigation coronal measurements had a mean error of 0.3° (+9 to −10.5). Four clinically valgus knees turned out varus with navigation. Mean BMI for this group was the same as the rest. Flexion deformity was similar between clinical and computer measurement. Three clinically normal knees showed significant varus in both X-ray and navigation. Compared directly, radiographic and navigation coronal deformity showed significant difference in the degree of deformity but not in the pattern of deformity. There was no correlation between BMI and both the error in clinical assessment of coronal deformity and navigation coronal alignment. If flexion deformity was > 5°, higher BMI indicates higher flexion deformity. There was a weak correlation between navigation coronal and flexion deformity.

Although error in clinical measurement did not reach statistical significance, based on our result, clinical assessment can give an incorrect pattern of deformity in up to 13% and hence should not be the sole basis of assessing deformity. Contrary to expectation, BMI did not influence error of clinical assessment or severity of coronal deformity. It however appeared to influence larger flexion deformities. The discrepancy between radiographic and navigation measurements reflects the absence of true weight bearing with navigation even though we tried to simulate this by applying axial load to the foot.

It is generally accepted that Hip-Knee-Ankle (long-leg) radiographs are a good measurement tool for biomechanical axis of the knee and they have been used as the outcome measure for many studies. Most of the surgeons recommend having pre operative and post operative long leg radiographs for total knee replacement surgery, although practice is not as common. We studied the biomechanical axis on long-leg films and compared it with computer navigation.

The objectives were to find out repeatability of measurements of biomechanical axis with inter observer readings on long leg radiographs and to compare biomechanical axis measurements with Navigation values obtained during total knee replacement surgery.

Our institution routinely uses long-leg radiographs for total knee replacement (TKR) surgery both pre- and post-operatively. A series of 209 patients who had navigated TKR between Jan 2007 and 2008 were selected. Stryker and Orthopilot systems for navigation were used. The intra-operative biomechanical axis measurements from the computer navigation files both pre-and post- implant were recorded. The long leg films were measured with a defined protocol from the digital images on PACS system. Centre of the head of femur was taken as the upper point. For the knee centre the midpoint of a line joining the distal femoral notch centre and upper tibia was used. For the ankle centre midpoint of the upper talar margin was used. An angle between the three points represented the radiological biomechanical axis. To investigate inter-observer error, two observers measured the pre- and post-operative biomechanical axis on long leg radiographs independently on 57 patients.

For the inter-observer measurements on 57 patients, the intraclass correlation coefficient was 0.99 for pre-operative radiographs and 0.98 for post-operative radiographs. Maximum difference between the two observers was 2° in four cases. All other cases showed the same readings or 1° difference.

There was a strong correlation, which was statistically significant, between the pre-operative radiographic and navigated measurements with Pearson correlation coefficient of 0.810 (p< 0.001). The maximum difference between the radiographic and navigated measurement was 24 degrees. The relationship between the postoperative measurements was weaker but statistically significant with Pearson correlation coefficient of 0.323 (p< 0.001). The maximum difference between the two methods of measurement was larger 15.5.

It can be concluded from this study that biomechanical axis on a long leg radiograph is a repeatable measure with good inter-observer correlation.

Although it is statistically significantly correlated with navigated readings, the absolute values may be different with both the methods. This raises the question on the reliability of long leg radiographs for the prediction of true biomechanical axis. Most of the larger value differences had a fixed flexion deformities (9 – 45 degrees). This can affect the readings on the long leg radiographs and make the deformity look either smaller or bigger. Also as our knee kinematic study has proven that the deformity does not remain the same in flexion as it was in extended knee that could also account for the difference in the readings. Other reasons for difference in the pre operative readings could be weight bearing status and surgical opening of the joint before taking the pre operative biomechanical axis measurements. Difference in the post operative readings could be attributed to weight bearing status, time length between navigation and radiographic measurements (6–12 wks), scarring of the soft tissues in the time and flexed posture of knee in the early post operative period.

It is generally accepted that Hip-Knee-Ankle (long-leg) radiographs are a good measurement tool for biomechanical axis of the knee and they have been used as the outcome measure for many studies. Most of the surgeons recommend having pre operative and post operative long leg radiographs for total knee replacement surgery, although practice is not as common. We studied the biomechanical axis on long-leg films and compared it with computer navigation. The aims were

To find out repeatability of measurements of biomechanical axis with inter observer readings on long leg radiographs

Our institution routinely uses long-leg radiographs for total knee replacement (TKR) surgery both pre- and postoperatively. A series of 209 patients who had navigated TKR between Jan 2007 and 2008 were selected. Stryker and Orthopilot systems for navigation were used. The intra-operative biomechanical axis measurements from the computer navigation files both pre-and post- implant were recorded. The long leg films were measured with a defined protocol from the digital images on PACS system. Centre of the head of femur was taken as the upper point.

For the knee centre the midpoint of a line joining the distal femoral notch centre and upper tibia was used. For the ankle centre midpoint of the upper talar margin was used. An angle between the three points represented the radiological biomechanical axis. To investigate inter-observer error, two observers measured the pre- and postoperative biomechanical axis on long leg radiographs independently on 57 patients. For the inter-observer measurements on 57 patients, the intraclass correlation coefficient was 0.99 for pre-operative radiographs and 0.98 for post-operative radiographs. Maximum difference between the two observers was 2° in four cases. All other cases showed the same readings or 1° difference. There was a strong correlation, which was statistically significant, between the pre-operative radiographic and navigated measurements with Pearson correlation coefficient of 0.810 (p< 0.001). The maximum difference between the radiographic and navigated measurement was 24 degrees. The relationship between the post-operative measurements was weaker but statistically significant with Pearson correlation coefficient of 0.323 (p< 0.001). The maximum difference between the two methods of measurement was larger 15.5.

It can be concluded from this study that biomechanical axis on a long leg radiograph is a repeatable measure with good inter-observer correlation. Although it is statistically significantly correlated with navigated readings, the absolute values may be different with each method. This raises the question of the reliability of long leg radiographs for the prediction of true biomechanical axis. Most of the larger value differences had a fixed flexion deformities (9 – 45 degrees). This can affect the readings on the long leg radiographs and make the deformity look either smaller or bigger. Also, our knee kinematic study has proven that the deformity does not remain the same in flexion and in the extended knee. This could also account for the difference in the readings. Other possible reasons for differences in the pre operative readings: the weight bearing status and the surgical opening of the joint, before taking the pre operative biomechanical axis measurements. Differences in the post operative readings could be attributed to: weight bearing status, time length between navigation and radiographic measurements (6–12 wks), scarring of the soft tissues in the meantime and flexed posture of knee in the early post operative period.

The aim of this study was to demonstrate a correlation between FASTRAK readings of spinal movement and established disability scores in-patients undergoing litigation.

A retrospective, blind study was conducted on patients who had been evaluated clinically between January 1994-October 1998. Statistical regression analysis between evaluated Oswestry Disability Score (ODS) and MSPQ/Zung questionnaires and the mean ROM was obtained. 49 patients with soft tissue injuries of the cervical (n = 14) and lumbar (n = 34) spine were assessed. All of them were undergoing litigation.

A standardised Fastrak trace measuring flexion, extension, right and left bending and rotation of the cervical and lumbar spine was recorded. An ODS and MSPQ/Zung questionnaire was filled in under the supervision of a senior physiotherapist.

There was no correlation between the ODS and MSPQ/Zung and mean ROM for the cervical spine. In the lumbar spine, flexion and ODS correlated statistically significantly (p< 0.01) and right rotation with the combined MSPQ/Zung score (p< 0.014).

This preliminary study is encouraging in that it demonstrates a direct correlation between FASTRAK measurements and recognised disability scores in the lumbar spine. Further analysis of non- litigation cohorts will contribute to establish these correlations.