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Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 38 - 38
1 Mar 2012
Al-Dadah O Shepstone L Donell ST
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Purpose of Study

To investigate the proprioceptive function of patients with an ACL rupture before and after reconstruction and correlate these findings with ligament laxity testing and clinical outcome measures.

Summary of Methods and Results

Fifty patients with an ACL rupture and 50 normal controls were recruited to the study. The Biodex Balance SD System was used to assess knee proprioception. This equipment measures proprioceptive function using an electronic platform. The balance of the subject is computed using stabilometry and an Overall Stability Index (OSI) is produced. A lower score reflects better proprioception. Knee stability was assessed clinically and with the Rolimeter knee arthrometer in all subjects. Participants were evaluated using the Tegner, Lysholm, Cincinnati and IKDC scoring systems. In the ACL group, 34 patients underwent ACL reconstruction and returned for their follow-up review 3 months post-operatively. The proprioceptive function of the injured knee of the ACL group (mean OSI 0.70) was significantly poorer compared to that of their uninjured knee (mean OSI 0.46, p<0.001, 95%CI 0.14, 0.34) and to the Normal Control group (mean OSI 0.49, p=0.01, 95%CI 0.05, 0.38). There was a significant improvement in proprioception of the injured knee following ACL reconstruction (mean OSI 0.47, p=0.003, 95%CI 0.10, 0.42). A significant correlation was found between pre-operative proprioception measurements and all the pre-operative knee outcome scores, however this correlation was not found post-operatively. No correlation was found between ligament laxity testing and either proprioception measurements or knee outcome scores.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_II | Pages 100 - 100
1 Feb 2012
Costa M Chester R Shepstone L Robinson A Donell S
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The aim of this study was to compare immediate weight-bearing mobilisation with traditional plaster casting in the rehabilitation of non-operatively treated Achilles tendon ruptures.

Forty-eight patients with Achilles tendon rupture were randomised into two groups. The treatment group was fitted with an off-the-shelf carbon-fibre orthotic and the patients were mobilised with immediate full weight-bearing. The control group was immobilised in traditional serial equinus plaster casts. The heel raise within the orthotic and the equinus position of the cast was reduced over a period of eight weeks and then the orthotic or cast was removed. Each patient followed the same rehabilitation protocol. The primary outcome measure was return to the patient's normal activity level as defined by the patient.

There was no statistical difference between the groups in terms of return to normal work [p=0.37] and sporting activity [p=0.63]. Nor was there any difference in terms of return to normal walking and stair climbing. There was weak evidence for improved early function in the treatment group.

There was 1 re-rupture of the tendon in each group and a further failure of healing in the control group. One patient in the control group died from a fatal pulmonary embolism secondary to a DVT in the ipsilateral leg.

Immediate weight-bearing mobilisation provides practical and functional advantages to patients treated non-operatively after Achilles tendon rupture. However, this study provides only weak evidence of faster rehabilitation.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_III | Pages 287 - 287
1 Jul 2011
Al-Dadah O Shepstone L Donell S
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There has been very little documented regarding the impact of meniscal injuries on knee proprioception. The aim of this study was to investigate the proprioceptive function of patients with meniscal tears and asses the influence that arthroscopic partial menisectomy has on knee proprioception.

One hundred subjects were recruited comprising an Arthroscopy group (50 patients) and a Normal Control group (50 subjects). The Biodex Balance SD System was used to assess proprioception. This equipment measures knee proprioception on an electronic platform. The balance of the subject is computed producing an Overall Stability Index (OSI). Lower scores reflect better proprioception. Knee stability was assessed clinically and with the Rolimeter knee arthrometer. The Lysholm and IKDC scoring systems were used to evaluate all the subjects.

Of the 50 subjects within the Arthroscopy group (all of whom had a normal ACL confirmed) 34 were found to have meniscal tears. Twenty-nine of the 34 patients with meniscal tears returned for their follow-up review 3 months post-operatively.

The proprioceptive function of the injured knee of the Arthroscopy group with meniscal tears (mean OSI 0.86) was significantly poorer compared to that of their uninjured knee (mean OSI 0.62, p< 0.001, 95%CI 0.14, 0.34) and to the Normal Control group (mean OSI 0.49, p< 0.001, 95%CI 0.21, 0.54). There was no significant improvement in their proprioceptive function following menisectomy (mean OSI 0.75, p=0.23, 95%CI −0.07, 0.28). There was a significant improvement of both the Lysholm (p=0.004) and IKDC (p=0.021) scores postoperatively.

Conclusion: These results indicate that there is a demonstrable proprioceptive deficit in patients with meniscal tears even in the presence of a normal ACL. This deficiency in proprioception did not improve within three months following arthroscopic partial menisectomy despite the improvement in functional outcome measures.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 235 - 235
1 Mar 2010
Candy E Stephenson R Jerosch-Herold C Shepstone L Farewell D
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Background and Purpose: There is a high prevalence of self reported back pain in the adolescent population. A randomised controlled trial (RCT) was undertaken to determine the effects of a high density foam seating wedge on back pain intensity.

Methods: The study took part in a large predominantly rural county in Eastern England. 185 students with back pain were recruited from 12 schools. Randomisation was stratified by school, and resulted in 92 students in the control and 93 in the intervention groups, respectively. The primary outcome measure was pain intensity (numerical rating 0–10 scale) recorded in pain diaries over 4 weeks. Following a one week baseline at the beginning of week 2, the intervention group were given a wedge to use on their school chairs. Linear effects models were used to analyse the pain intensity data.

Results: 97 students (46 control, 51 intervention) completed the RCT. For the intervention group, pain intensity was significantly reduced during the 3 weeks when the wedge was used (0.013 point reduction per half day, 95%CI −0.025 to −0.001, p=0.04). Evening pain was significantly less for the intervention group (0.324 reduction, 95%CI −0.543 to −0.104, p≤0.01).

Conclusion: The introduction of the wedge significantly reduced back pain intensity especially in the evenings. Despite its benefits some students found carrying the wedge a nuisance. It is therefore only suitable to relieve back pain in the short term. The results suggest that further research into the longer-term effect of alternative, permanent, seating on pain intensity in adolescents should be completed.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 229 - 229
1 Jul 2008
Costa M Robinson F Donell S Shepstone L Chester R
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We performed two independent randomised controlled trials to assess the potential benefits of immediate weight-bearing mobilisation for Achilles tendon ruptures. The first trial on surgically treated patients provides strong evidence of improved functional outcome for patients mobilised fully weight-bearing after operative repair of their Achilles tendon rupture. The two cases of re-rupture in the treatment group suggest that careful patient selection may be required as patients need to follow a structured rehabilitation regime.

The second trial performed upon non-operatively treated patients provides only weak evidence of a functional benefit from immediate weight-bearing mobilisation. However, the practical advantages of immediate weight-bearing did not predispose the patients to a higher complication rate. In particular there was no evidence of tendon lengthening or a higher re-rupture rate. We would therefore advocate the use of immediate weight-bearing mobilisation for the rehabilitation of all patients with rupture of the Achilles tendon.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_I | Pages 15 - 16
1 Mar 2008
Costa M Shepstone L Donell S Thomas T
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The aim of this study was to test the efficacy of shock-wave therapy for chronic Achilles pain. Forty-nine patients with Achilles tendon pain for a minimum of 4 months were included in the study. Patients were randomised to either shockwave therapy (n=27) or placebo control (n=22). The treatment group were given 2000 shocks at up to 1500 mJ/mm2 per shock. The control (sham) treatment was applied using the same parametres but the shockwaves were dispersed before they reached the patient. Each patient was treated once a month over 3 months. The primary outcome measure was pain on walking indicated on a 100mm visual analogue score (VAS) at 3 months. The walking pain scores were very similar at baseline between the two groups. In the treatment group the mean (standard deviation) was 55.5 mm (30.6) and in the control group 55.6mm (26.5). By 3 months, the pain scores had reduced in both groups to a mean (standard deviation) of 34.5 mm (34.2) and 50.3 mm (36.3). Although lower in the treatment group this difference was not statistically significant at the 5% level (t-test, p=0.127, 95% CI : −4.7 to 36.2). Two elderly patients in the treatment group sustained spontaneous rupture of the tendon after falls during the course of the trial. The results of this trial provided no evidence for the use of shockwave therapy in the treatment of patients with chronic Achilles tendinopathy. However, a treatment effect cannot be ruled out since the 95% confidence interval included a potential clinically relevant difference. The two cases of rupture suggest extreme caution in treating the elderly.


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_III | Pages 372 - 372
1 Oct 2006
Hing C Shepstone L Marshall T Donell S
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Introduction: Patellofemoral instability (PFI) is a disabling condition that occurs in adolescence. Recurrence after patellar dislocation has been reported in 2–50% of cases. This study aimed to compare the shape of the distal femur in PFI to a normal cohort.

Method: 108 CT scans from 54 subjects with PFI were compared to 197 CT scans from 102 normal subjects. Outlines of the trochlear groove and lateral condyle were extracted from CT scans using Interactive Data Language version 5.0 image manipulation software. The shapes were aligned using a modified Procrustes analysis and interpolation performed with a basic cubic spline. A statistical method from the field of functional data analysis was used to quantify shape. A discriminant analysis was then used to provide a tool for deciding which patients had abnormal grooves thus improving patient selection for trochleoplasty.

Results: Mathematical quantification showed a significant difference at the 0.001 level using an independent t-test between the normal and PFI groups for the shape of the trochlear groove with PFI knees having a more complex shape than normal. The second largest source of variation is in the position of the trochlear groove minimum with respect to the coronal plane together with variation in the shape of the medial condyle. The trochlear groove is situated more medially, with a shallower medial condyle, in PFI. In contrast the trochlear groove is situated more laterally, with a more prominent medial condyle in normal knees. Analysis of shape of the lateral condyle showed that in PFI, it is shorter and broader.

Conclusion: Principal components analysis can be used to quantify the variation in shape of the distal femur and allow a discriminant function analysis to be performed comparing PFI knees to normal knees. This quantification of shape can be applied to diagnosis of instability, operative planning for trochleoplasty and implant design.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 8 | Pages 1048 - 1052
1 Aug 2006
Jerosch-Herold C Rosén B Shepstone L

Locognosia, the ability to localise touch, is one aspect of tactile spatial discrimination which relies on the integrity of peripheral end-organs as well as the somatosensory representation of the surface of the body in the brain. The test presented here is a standardised assessment which uses a protocol for testing locognosia in the zones of the hand supplied by the median and/or ulnar nerves.

The test-retest reliability and discriminant validity were investigated in 39 patients with injuries to the median or ulnar nerve. Intraclass correlation coefficients were used to calculate the test-retest reliability. Discriminant validity was assessed by comparing the injured with the unaffected hand.

Excellent test-retest reliability was demonstrated for the injuries to the median (intraclass correlation coefficient 0.924, 95% confidence interval 0.848 to 1.00) and the ulnar nerves (intraclass correlation coefficient 0.859, 95% confidence interval 0.693 to 1.00). The magnitude of the difference in scores between affected and unaffected hands showed good discriminant validity. For injuries to the median nerve the mean difference was 11.1 points (1 to 33; sd 7.4), which was statistically significant (p < 0.0001, paired t-test) and for those of the ulnar nerve it was 4.75 points (1 to 13.5; sd 3.16), which was also statistically significant (paired t-test, p < 0.0001).

The locognosia test has excellent test-retest reliability, is a valid test of tactile spatial discrimination and should be included in the evaluation of outcome after injury to peripheral nerves.


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_I | Pages 166 - 166
1 Mar 2006
Costa M Chester R Shepstone L Robinson A Donell S
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Aim The aim of this study was to compare immediate weightbearing mobilisation to traditional plaster casting in the rehabilitation of acute repaired Achilles tendon ruptures.

Methods 48 patients with acute repaired Achilles tendon ruptures consented to enter the trial. Patients were randomised into two groups. The treatment group were fitted with an off-the-shelf carbon-fibre orthotic and were mobilised fully weightbearing. The equinus position of the ankle joint was reduced over a period of 8 weeks and the orthotic was then removed. The control group were immobilised in traditional serial equinus plaster casts. The equinus position of the cast was reduced over the same 8 week period with weightbearing for only the last 2 weeks. The primary outcome measure was return to the patient’s normal activity level. An independent observer, blind to treatment, recorded secondary clinical, anthropometric and patient-centred outcomes. Follow-up was for one year.

Results There were 23 patients in the treatment group and 25 in the control group. Results show median in weeks (95% C.I.), p-values are based upon a log-rank test.

Return to sport was 39.0 (18.0 to 60.0) in the treatment group and 26.0 (40.0 to 90.0) in the control group, p = 0.341.

Return to normal walking was 12.0 (10.0 to 18.0) in the treatment group and 18.0 (18.0 to 22.0) in the control group, p < 0.001.

Return to stair climbing was 13.0 (10.0 to 15.0) in the treatment group and 22.0 (18.0 to 22.0) in the control group, p < 0.001.

Return to work was 9.0 (2.0 to 9.0) in the treatment group and 4.0 (1.0 to 13.0) in the control group, p = 0.984.

There were 2 re-ruptures of the tendon in the treatment group. One occurred when the patient slipped on ice whilst wearing the orthotic. The other whilst running 3 months after the initial injury. One patient who had an augmented tendon repair and then plaster casting, required plastic surgery for a major wound complication. In addition, there were 8 minor wound-related complications in the control group and 6 in the treatment group.

Conclusion Immediate weightbearing mobilisation provides practical advantages to patients after Achilles tendon repair. The median return to activity was significantly shorter in the treatment group for return to normal walking and return to stair climbing but not for return to work or sporting activity.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 1 | Pages 69 - 77
1 Jan 2006
Costa ML MacMillan K Halliday D Chester R Shepstone L Robinson AHN Donell ST

We performed two independent, randomised, controlled trials in order to assess the potential benefits of immediate weight-bearing mobilisation after rupture of the tendo Achillis. The first trial, on operatively-treated patients showed an improved functional outcome for patients mobilised fully weight-bearing after surgical repair. Two cases of re-rupture in the treatment group suggested that careful patient selection is required as patients need to follow a structured rehabilitation regimen. The second trial, on conservatively-treated patients, provided no evidence of a functional benefit from immediate weight-bearing mobilisation. However, the practical advantages of immediate weight-bearing did not predispose the patients to a higher complication rate. In particular, there was no evidence of tendon lengthening or a higher re-rupture rate. We would advocate immediate weight-bearing mobilisation for the rehabilitation of all patients with rupture of the tendo Achillis.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 223 - 224
1 Sep 2005
Costa M Shepstone L Donell S Thomas T
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Acute Achilles tendon pain is a common clinical entity, particularly in sportsmen and women. Fortunately, the majority of such pain is self limiting. However, there are a significant number of people for whom the pain becomes chronic and debilitating. A recent Cochrane review found that there was no randomised controlled evidence of an effective treatment for chronic Achilles pain. The aim of this study was to test the efficacy of shockwave therapy in a double-blind randomised controlled trial. The study has the approval of Local Research Ethics Committees.

Forty nine patients with Achilles tendon pain for a minimum of 4 months were included in the study. Patients were randomised to either shockwave therapy (n=27) or sham dose control therapy (n=22). Ultrasound was used to focus the shocks onto the affected area of tendon. The treatment group were given 2000 shocks at upto 1500mJ per shock, titrated to the patients pain tolerance. The control (sham) treatment was applied using the same parametres but with bubble-wrap interposition between the shockwave generator and the Achilles, to disperse the shockwaves. Each patient was treated once a month over 3 months. Primary outcome measure was pain on walking indicated on a 100mm visual analogue score (VAS) at 3 months. Secondary outcome measures included clinical and patient centred questionnaire scores. . An intention-to-treat approach was used for the analysis. Where patients had missing pain scores at 3 month follow-up, the last available pain score was carried forward.

The walking pain scores were very similar at baseline between the two groups. In the treatment group the mean (standard deviation) was 55.5mm (30.6) and in the control group 55.6mm (26.5). By 3 months, the pain scores had reduced in both groups to a mean (standard deviation) of 34.5 mm (34.2) and 50.3 mm (36.3). Although lower in the treatment group this difference was not statistically significant at the 5% level (t-test, p = 0.127, 95% C.I. : −4.7 to 36.2). No statistically significant differences were found with respect to any of the other clinical variables.

Two elderly patients in the treatment group sustained spontaneous rupture of the tendon after falls, during the course of the trial.

The results of this trial provided no evidence for the use of shockwave therapy in the treatment of patients with chronic Achilles tendinopathy. However, a treatment effect cannot be ruled out since the 95% confidence interval was wide and included a potential clinically relevant difference. The 2 cases of rupture suggest extreme caution in treating the elderly.


The Journal of Bone & Joint Surgery British Volume
Vol. 87-B, Issue 4 | Pages 458 - 462
1 Apr 2005
Walton NP Darrah C Shepstone L Donell ST Phillips H

We prospectively studied 217 patients who underwent 234 Elite Plus total hip arthroplasties. At a mean of 6.4 (SD 0.7) years post-operatively, 39 patients had died and 22 were either lost to follow-up or had no radiographs available. Clinical (Oxford hip score) and radiological assessments were performed on 156 patients (168 hip arthroplasties) who had a mean age of 67.7 (SD 9.7) years at operation.

In the assessed group, 26 of 159 (16.4%) of femoral stems which had not already been revised and 19 of 159 (11.9%) of acetabular cups were definitely loose. In total, 52 of 168 (31%) of hips had either been revised or had definite evidence of loosening of a component. We could not establish any relationship between clinical and radiological outcomes.

Despite the fact that the clinical outcome and rate of revision for the Elite Plus appeared to meet international standards, our findings give us cause for concern. We believe that joint registries should include radiological surveillance in order to provide reliable information about medium-term outcomes for hip prostheses.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_I | Pages 43 - 43
1 Jan 2003
Davies A Costa M Shepstone L Donell S Glasgow M
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Anterior knee pain attributable to the patellofemoral joint and extensor mechanism dysplasia is a common presentation to Orthopaedic surgeons. Plain radiology is likely to remain the primary investigation of the knee in most centres, but most of the radiological features of extensor mechanism dysplasia are time consuming and difficult to measure reproducibly. 137 consecutive symptomatic knees aged under 30, referred to an Orthopaedic surgeon were studied in order to identify a rapid and reproducible marker for those knees worthy of further in-depth analysis.

Overall, 67 knees (49%) had at least one radiological abnormality and 70 (51%) were considered ‘normal’. There were 5 Dejour Type3 dysplasias of the femoral trochlea, 9 Type2 and 12 Type1. There were 49 cases of patella alta and 5 of patella infera. Four knees had an abnormal lateral patellofemoral (patellar tilt) angle. 15 knees had more than one abnormality. The classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of lateral patellofemoral angles. Patellar height was more easily measured but took time. The sulcus angle emerged as an easily and rapidly measurable feature that was reproducible and was closely related to the other features of extensor mechanism dysplasia.

The sulcus angle offers a rapid and reliable ‘screening’ measurement on knee radiographs. A normal sulcus angle suggests that seeking the other radiological markers of extensor mechanism malalignment is unlikely to reveal additional useful information. Other diagnoses can then be sought. The more abnormal the sulcus angle, the more severe the other features of extensor mechanism dysplasia are likely to be. Further detailed measurements can then help to define the most appropriate surgical correction.


Orthopaedic Proceedings
Vol. 84-B, Issue SUPP_II | Pages 157 - 158
1 Jul 2002
Davies A Bayer J Owen-Johnstone S Darrah C Shepstone L Glasgow M Donell S
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A prospective clinical investigation to determine the optimum knee flexion angle for the ‘skyline’ patellofemoral joint radiograph.

Plain radiography of the patello-femoral joint includes the axial or ‘skyline’ radiograph. The optimum knee flexion angle for making this image remains unclear.

We therefore performed a prospective clinical study in which patients underwent three skyline radiographs with knee flexion angles of 30(or minimal flexion), 50 and 90 degrees. The patients were new patients, aged between 12 and 30, presenting to a knee clinic with anterior knee pain. Two observers evaluated the radiographs, making a standardised series of measurements. Blinding was organised so that the observers were unable to use any information other than the radiographic image alone. One observer evaluated all the films on two separate occasions to allow calculation of intra- and interassessor agreement.

There were 67 knees from 46 patients. There was a high level of intra- and inter-observer agreement. There were a number of patients in which the radiographic appearance of the patello-femoral varied markedly between the different views; in all cases the abnormality was best demonstrated by the 30-degree view. There were however a number of minimal flexion views in which the film contained incomplete information because part of the patello-femoral joint was missing from the image.

We conclude that whilst a minimal flexion skyline view is the most sensitive method for the detection of patellar tilt and subluxation, not all knees can be successfully imaged at the required position. A flexible approach is therefore needed, to obtain satisfactory images at minimal flexion.


Orthopaedic Proceedings
Vol. 84-B, Issue SUPP_II | Pages 164 - 164
1 Jul 2002
Blundell CM Shepstone L Donell ST Marshall T
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The positioning of components in knee replacement is related to outcome and for this reason a study has been conducted to compare the exact position of the tibial and femoral components in total knee arthroplasty with the placement as judged by the surgeon at the time of operation.

Operating surgeons of a range of grades completed a pro-forma immediately after operating on 25 patients having total knee replacement. Patients were entered into the study by consent providing that they had osteoarthritis and this was their first ever lower limb joint replacement. The form detailed where the surgeon considered he had placed the femoral component in the coronal plane and in terms of rotation upon the femur. They were asked to state what lines or angles of reference they had used and whether they had used intra or extra medullary jigs. Likewise for the tibia, implant position was detailed for coronal, sagittal and transverse planes. The proforma stated the grade of operating surgeon but were otherwise kept anonymous.

All study patients had pre and postoperative CT scans. These involved an AP scannogram and transverse sections, according to a protocol, through the femoral neck, femoral condyles, tibial plateau and ankle. By comparing bony landmarks seen on the pre-operative CT scans with lines of reference from the components post-operatively the exact position of the implant was determined in the transverse and coronal planes. For the sagittal plane (slope) the standard lateral X-ray was used.

For the femur all operations were carried out using intra-medullary jigs. For the femoral component the difference was not significant between the measured position and the surgeons estimate in any plane (p=0.937 for coronal and p=0.432 for transverse). The measured position of the component was not related to the grade of the operating surgeon nor to the axis nor technique of reference used.

For the tibial component, coronal alignment was significantly different (p=0.001) with the measured position being in more varus than was estimated. The range of transverse placement was from 4° of external rotation to 35° of internal rotation of the tibial prosthesis with reference to the tibial tubercle centre. This was significantly different to that estimated by the surgeon (p< 0.001). Estimation of slope in the sagittal plane was good. None of these differences were related to operator grade. For 15 of the TKR’s the tibail component was aligned using intra-medullary techniques. This was related to the accuracy of positioning of the prosthesis with significantly better estimation compared to those in which extra-medulary jigs had been used (p=0.002 for the transverse plane and p=0.065 for the coronal plane).

This study has demonstarted that surgeons are able to accurately judge the position of insertion of the femoral component in total knee replacement. Surgeons are poor at estimating the position of the tibial component in the transverse and coronal planes but better in the sagittal plane. Due to the difficulty in its assessment rotational alignment has been ignored in arthroplasty but as with alignment in the other planes it is likely to have a bearing on outcome. Improved techniques to help us judge placement of knee components are needed.


The Journal of Bone & Joint Surgery British Volume
Vol. 82-B, Issue 8 | Pages 1162 - 1166
1 Nov 2000
Davies AP Costa ML Donnell ST Glasgow MM Shepstone L

Anterior knee pain due to dysplasia of the extensor mechanism is common. We have studied 137 knees (103 patients) in order to identify a rapid and reproducible radiological feature which would indicate the need for further analysis.

Overall, 67 knees (49%) had at least one radiological abnormality; 70 (51%) were considered normal. There were five cases of Dejour type-3 dysplasia of the femoral trochlea, nine of type-2 and 12 of type-1. There were 49 cases of patella alta and five of patella infera. Four knees had an abnormal lateral patellofemoral angle (patellar tilt), and in 15 knees there was more than one abnormality. Classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of the lateral patellofemoral angle. Patellar height was more easily measured but took time. The sulcus angle is an easily and rapidly measurable feature which was reproducible and was closely related to other features of dysplasia of the extensor mechanism.

The finding of a normal sulcus angle suggested that seeking other radiological evidence of malalignment of the extensor mechanism was unlikely to reveal additional useful information. The severity of other features of dysplasia of the extensor mechanism correlated with increasing sulcus angle.