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The Bone & Joint Journal
Vol. 106-B, Issue 7 | Pages 744 - 750
1 Jul 2024
Saeed A Bradley CS Verma Y Kelley SP

Aims

Radiological residual acetabular dysplasia (RAD) has been reported in up to 30% of children who had successful brace treatment of infant developmental dysplasia of the hip (DDH). Predicting those who will resolve and those who may need corrective surgery is important to optimize follow-up protocols. In this study we have aimed to identify the prevalence and predictors of RAD at two years and five years post-bracing.

Methods

This was a single-centre, prospective longitudinal cohort study of infants with DDH managed using a published, standardized Pavlik harness protocol between January 2012 and December 2016. RAD was measured at two years’ mean follow-up using acetabular index-lateral edge (AI-L) and acetabular index-sourcil (AI-S), and at five years using AI-L, AI-S, centre-edge angle (CEA), and acetabular depth ratio (ADR). Each hip was classified based on published normative values for normal, borderline (1 to 2 standard deviations (SDs)), or dysplastic (> 2 SDs) based on sex, age, and laterality.


The Bone & Joint Journal
Vol. 105-B, Issue 8 | Pages 935 - 942
1 Aug 2023
Bradley CS Verma Y Maddock CL Wedge JH Gargan MF Kelley SP

Aims

Brace treatment is the cornerstone of managing developmental dysplasia of the hip (DDH), yet there is a lack of evidence-based treatment protocols, which results in wide variations in practice. To resolve this, we have developed a comprehensive nonoperative treatment protocol conforming to published consensus principles, with well-defined a priori criteria for inclusion and successful treatment.

Methods

This was a single-centre, prospective, longitudinal cohort study of a consecutive series of infants with ultrasound-confirmed DDH who underwent a comprehensive nonoperative brace management protocol in a unified multidisciplinary clinic between January 2012 and December 2016 with five-year follow-up radiographs. The radiological outcomes were acetabular index-lateral edge (AI-L), acetabular index-sourcil (AI-S), centre-edge angle (CEA), acetabular depth ratio (ADR), International Hip Dysplasia Institute (IHDI) grade, and evidence of avascular necrosis (AVN). At five years, each hip was classified as normal (< 1 SD), borderline dysplastic (1 to 2 SDs), or dysplastic (> 2 SDs) based on validated radiological norm-referenced values.


The Bone & Joint Journal
Vol. 104-B, Issue 9 | Pages 1081 - 1088
1 Sep 2022
Behman AL Bradley CS Maddock CL Sharma S Kelley SP

Aims

There is no consensus regarding optimum timing and frequency of ultrasound (US) for monitoring response to Pavlik harness (PH) treatment in developmental dysplasia of the hip (DDH). The purpose of our study was to determine if a limited-frequency hip US assessment had an adverse effect on treatment outcomes compared to traditional comprehensive US monitoring.

Methods

This study was a single-centre noninferiority randomized controlled trial. Infants aged under six months whose hips were reduced and centred in the harness at initiation of treatment (stable dysplastic or subluxable), or initially decentred (subluxated or dislocated) but reduced and centred within four weeks of PH treatment, were randomized to our current standard US monitoring protocol (every clinic visit) or to a limited-frequency US protocol (US only at end of treatment). Groups were compared based on α angle and femoral head coverage at the end of PH treatment, acetabular indices, and International Hip Dysplasia Institute (IHDI) grade on one-year follow-up radiographs.


The Bone & Joint Journal
Vol. 104-B, Issue 7 | Pages 811 - 819
1 Jul 2022
Galvain T Mantel J Kakade O Board TN

Aims

The aim of this study was to estimate the clinical and economic burden of dislocation following primary total hip arthroplasty (THA) in England.

Methods

This retrospective evaluation used data from the UK Clinical Practice Research Datalink database. Patients were eligible if they underwent a primary THA (index date) and had medical records available 90 days pre-index and 180 days post-index. Bilateral THAs were excluded. Healthcare costs and resource use were evaluated over two years. Changes (pre- vs post-THA) in generic quality of life (QoL) and joint-specific disability were evaluated. Propensity score matching controlled for baseline differences between patients with and without THA dislocation.


The Bone & Joint Journal
Vol. 102-B, Issue 10 | Pages 1311 - 1318
3 Oct 2020
Huang Y Gao Y Li Y Ding L Liu J Qi X

Aims

Morphological abnormalities are present in patients with developmental dysplasia of the hip (DDH). We studied and compared the pelvic anatomy and morphology between the affected hemipelvis with the unaffected side in patients with unilateral Crowe type IV DDH using 3D imaging and analysis.

Methods

A total of 20 patients with unilateral Crowe-IV DDH were included in the study. The contralateral side was considered normal in all patients. A coordinate system based on the sacral base (SB) in a reconstructed pelvic model was established. The pelvic orientations (tilt, rotation, and obliquity) of the affected side were assessed by establishing a virtual anterior pelvic plane (APP). The bilateral coordinates of the anterior superior iliac spine (ASIS) and the centres of hip rotation were established, and parameters concerning size and volume were compared for both sides of the pelvis.


The Bone & Joint Journal
Vol. 101-B, Issue 7_Supple_C | Pages 77 - 83
1 Jul 2019
James EW Blevins JL Gausden EB Turcan S Denova TA Satalich JR Ranawat AS Warren RF Ranawat AS

Aims

Anterior cruciate ligament (ACL) and multiligament knee (MLK) injuries increase the risk of development of knee osteoarthritis and eventual need for total knee arthroplasty (TKA). There are limited data regarding implant use and outcomes in these patients. The aim of this study was to compare the use of constrained implants and outcomes among patients undergoing TKA with a history of prior knee ligament reconstruction (PKLR) versus a matched cohort of patients undergoing TKA with no history of PKLR.

Patients and Methods

Patients with a history of ACL or MLK reconstruction who underwent TKA between 2007 and 2017 were identified in a single-institution registry. There were 223 patients who met inclusion criteria (188 ACL reconstruction patients, 35 MLK reconstruction patients). A matched cohort, also of 223 patients, was identified based on patient age, body mass index (BMI), sex, and year of surgery. There were 144 male patients and 79 female patients in both cohorts. Mean age at the time of TKA was 57.2 years (31 to 88). Mean BMI was 29.7 kg/m2 (19.5 to 55.7).


The Bone & Joint Journal
Vol. 100-B, Issue 10 | Pages 1399 - 1404
1 Oct 2018
Biedermann R Riccabona J Giesinger JM Brunner A Liebensteiner M Wansch J Dammerer D Nogler M

Aims. The purpose of this study was to analyze the incidence of the different ultrasound phenotypes of developmental dysplasia of the hip (DDH), and to determine their subsequent course. Patients and Methods. A consecutive series of 28 092 neonates was screened and classified according to the Graf method as part of a nationwide surveillance programme, and then followed prospectively. Abnormal hips were followed until they became normal (Graf type I). Type IIb hips and higher grades were treated by abduction in a Tübinger orthosis until normal. Dislocated hips underwent closed or open reduction. Results. Overall, 90.2% of hips were normal at birth. Type IIa hips (8.9%) became normal at a median of six weeks (interquartile range (IQR) 6 to 9). Type IIc and IId hips (0.67%) became normal after ten weeks (IQR 7 to 13). There were 19 type lll and eight type lV hips at baseline. There were 24 closed reductions and one open reduction. No late presentations of DDH were detected within the first five years of life. Conclusion. The incidence of DDH was eight per 1000 live births. The treatment rate was 1% (n = 273). The rate of first operations on the newborn hip was 0.86, and rate of open surgery was 0.04. The cumulative rate of open surgery was 0.07. The authors take the view that early identification and treatment in abduction of all dysplastic hips in early childhood reduces the rate of open reduction and secondary DDH-related surgery later in life. Cite this article: Bone Joint J 2018;100-B:1399–1404


The Bone & Joint Journal
Vol. 99-B, Issue 11 | Pages 1533 - 1536
1 Nov 2017
Nie K Rymaruk S Paton RW

Aims. A clicky hip is a common referral for clinical and sonographic screening for developmental dysplasia of the hip (DDH). There is controversy regarding whether it represents a true risk factor for pathological DDH. Therefore a 20-year prospective, longitudinal, observational study was undertaken to assess the relationship between the presence of a neonatal clicky hip and pathological DDH. Patients and Methods. A total of 362 infants from 1997 to 2016 were referred with clicky hips to our ‘one-stop’ paediatric hip screening clinic. Hips were assessed clinically for instability and by ultrasound imaging using a simplified Graf/Harcke classification. Dislocated or dislocatable hips were classified as Graf Type IV hips. Results. The mean age at presentation was 13.8 weeks (12.8 to 14.7). In all 351 out of 362 children (97.0%) had Graf Type I hips (normal) that required no treatment. Nine children (2.5%) had Graf Type II hips but all resolved to Graf Type I hips on follow-up scans. One child (0.3%) had Graf Type III hip dysplasia and one child (0.3%) had an irreducible hip dislocation. The two pathological hips were associated with unilateral limited hip abduction. Mean referrals increased from 12.9 to 23.3 each year (p = 0.002) from the first decade of the study to the second, driven by increasing primary care referrals (5.5 versus 16.7 per year, p < 0.001). Conclusion. Most clicky hips required no treatment other than reassurance to parents. Clicky hips with a normal hip examination should be considered a variant of normal childhood and not a risk factor for DDH. However, an abnormal hip examination including unilateral limited hip abduction should prompt urgent further investigations. Cite this article: Bone Joint J 2017;99-B:1533–6


The Bone & Joint Journal
Vol. 97-B, Issue 11 | Pages 1493 - 1499
1 Nov 2015
Pandit H Hamilton TW Jenkins C Mellon SJ Dodd CAF Murray DW

This prospective study reports the 15-year survival and ten-year functional outcome of a consecutive series of 1000 minimally invasive Phase 3 Oxford medial UKAs (818 patients, 393 men, 48%, 425 women, 52%, mean age 66 years; 32 to 88). These were implanted by two surgeons involved with the design of the prosthesis to treat anteromedial osteoarthritis and spontaneous osteonecrosis of the knee, which are recommended indications. Patients were prospectively identified and followed up independently for a mean of 10.3 years (5.3 to 16.6).

At ten years, the mean Oxford Knee Score was 40 (standard deviation (sd) 9; 2 to 48): 79% of knees (349) had an excellent or good outcome. There were 52 implant-related re-operations at a mean of 5.5 years (0.2 to 14.7). The most common reasons for re-operation were arthritis in the lateral compartment (2.5%, 25 knees), bearing dislocation (0.7%, seven knees) and unexplained pain (0.7%, seven knees). When all implant-related re-operations were considered as failures, the ten-year rate of survival was 94% (95% confidence interval (CI) 92 to 96) and the 15-year survival rate 91% (CI 83 to 98). When failure of the implant was the endpoint the 15-year survival was 99% (CI 96 to 100).

This is the only large series of minimally invasive UKAs with 15-year survival data. The results support the continued use of minimally invasive UKA for the recommended indications.

Cite this article: Bone Joint J 2015;97-B:1493–99.


The Bone & Joint Journal
Vol. 97-B, Issue 2 | Pages 164 - 172
1 Feb 2015
Grammatopoulos G Thomas GER Pandit H Beard DJ Gill HS Murray DW

We assessed the orientation of the acetabular component in 1070 primary total hip arthroplasties with hard-on-soft, small diameter bearings, aiming to determine the size and site of the target zone that optimises outcome. Outcome measures included complications, dislocations, revisions and ΔOHS (the difference between the Oxford Hip Scores pre-operatively and five years post-operatively). A wide scatter of orientation was observed (2sd 15°). Placing the component within Lewinnek’s zone was not associated withimproved outcome. Of the different zone sizes tested (± 5°, ± 10° and ± 15°), only ± 15° was associated with a decreased rate of dislocation. The dislocation rate with acetabular components inside an inclination/anteversion zone of 40°/15° ± 15° was four times lower than those outside. The only zone size associated with statistically significant and clinically important improvement in OHS was ± 5°. The best outcomes (ΔOHS > 26) were achieved with a 45°/25° ± 5° zone.

This study demonstrated that with traditional technology surgeons can only reliably achieve a target zone of ±15°. As the optimal zone to diminish the risk of dislocation is also ±15°, surgeons should be able to achieve this. This is the first study to demonstrate that optimal orientation of the acetabular component improves the functional outcome. However, the target zone is small (± 5°) and cannot, with current technology, be consistently achieved.

Cite this article: Bone Joint J 2015;97-B:164–72.


The Bone & Joint Journal
Vol. 96-B, Issue 11 | Pages 1546 - 1552
1 Nov 2014
Hägglund G Alriksson-Schmidt A Lauge-Pedersen H Rodby-Bousquet E Wagner P Westbom L

In 1994 a cerebral palsy (CP) register and healthcare programme was established in southern Sweden with the primary aim of preventing dislocation of the hip in these children.

The results from the first ten years were published in 2005 and showed a decrease in the incidence of dislocation of the hip, from 8% in a historical control group of 103 children born between 1990 and 1991 to 0.5% in a group of 258 children born between 1992 and 1997. These two cohorts have now been re-evaluated and an additional group of 431 children born between 1998 and 2007 has been added.

By 1 January 2014, nine children in the control group, two in the first study group and none in the second study group had developed a dislocated hip (p < 0.001). The two children in the first study group who developed a dislocated hip were too unwell to undergo preventive surgery. Every child with a dislocated hip reported severe pain, at least periodically, and four underwent salvage surgery. Of the 689 children in the study groups, 91 (13%) underwent preventive surgery.

A population-based hip surveillance programme enables the early identification and preventive treatment, which can result in a significantly lower incidence of dislocation of the hip in children with CP.

Cite this article: Bone Joint J 2014; 96-B:1546–52.


The Bone & Joint Journal
Vol. 95-B, Issue 5 | Pages 616 - 622
1 May 2013
Horstmann WG Swierstra MJ Ohanis D Castelein RM Kollen BJ Verheyen CCPM

Autologous retransfusion and no-drainage are both blood-saving measures in total hip replacement (THR). A new combined intra- and post-operative autotransfusion filter system has been developed especially for primary THR, and we conducted a randomised controlled blinded study comparing this with no-drainage.

A total of 204 THR patients were randomised to autologous blood transfusion (ABT) (n = 102) or no-drainage (n = 102). In the ABT group, a mean of 488 ml (sd 252) of blood was retransfused. The mean lowest post-operative haemoglobin level during the hospital stay was higher in the autotransfusion group (10.6 g/dl (7.8 to 13.9) vs 10.2 g/dl (7.5 to 13.3); p = 0.01). The mean haemoglobin levels for the ABT and no-drainage groups were not significantly different on the first day (11.3 g/dl (7.8 to 13.9) vs 11.0 g/dl (8.1 to 13.4); p = 0.07), the second day (11.1 g/dl (8.2 to 13.8) vs 10.8 g/dl (7.5 to 13.3); p = 0.09) or the third day (10.8 g/dl (8.0 to 13.0) vs 10.6 g/dl (7.5 to 14.1); p = 0.15). The mean total peri-operative net blood loss was 1464 ml (sd 505) in the ABT group and 1654 ml (sd 553) in the no-drainage group (p = 0.01). Homologous blood transfusions were needed in four patients (3.9%) in the ABT group and nine (8.8%) in the no-drainage group (p = 0.15). No statistically significant difference in adverse events was found between the groups.

The use of a new intra- and post-operative autologous blood transfusion filter system results in less total blood loss and a smaller maximum decrease in haemoglobin levels than no-drainage following primary THR.

Cite this article: Bone Joint J 2013;95-B:616–22.


The Bone & Joint Journal
Vol. 95-B, Issue 2 | Pages 266 - 270
1 Feb 2013
Uludag S Seyahi A Orak MM Bilgili MG Colakoglu B Demirhan M

Several authors have suggested that the final five weeks of gestation are a critical period for the development of the hip. In order to test the hypothesis that gestational age at birth may influence the development of the hip joint, we analysed the sonographic findings in 1992 hips (in 996 term newborns) with no risk factor for developmental dysplasia of the hip. The 996 infants were born at a mean gestational age of 39 weeks (37 to 41).

The mean bony roof angle (α), cartilage roof angle (β) and the distribution of the type of hip were compared between the 37th, 38th, 39th, 40th and 41st birth week groups. There was a significant difference in the distribution of type of hip between the different birth week groups (p < 0.001), but no significant difference between the α angles of all groups (p = 0.32). There was no correlation between birth week and roof angle (p = 0.407 and p = 0.291, respectively) and no significant correlation between birth weight and roof angle (p = 0.735 and p = 0.132, respectively).

The maturity of the infant hip, as assessed sonographically, does not appear to be affected by gestational age, and the fetal development of the acetabular roof appears to plateau from 37 weeks.

Cite this article: Bone Joint J 2013;95-B:266–70.


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 11 | Pages 1534 - 1539
1 Nov 2012
Karataglis D Papadopoulos P Boutsiadis A Fotiadou A Ditsios K Hatzokos I Christodoulou A

This study evaluates the position of the long head of biceps tendon using ultrasound following simple tenotomy, in patients with arthroscopically repaired rotator cuff tears.

In total, 52 patients with a mean age of 60.7 years (45 to 75) underwent arthroscopic repair of the rotator cuff and simple tenotomy of the long head of biceps tendon. At two years post-operatively, ultrasound revealed that the tendon was inside the bicipital groove in 43 patients (82.7%) and outside in nine (17.3%); in six of these it was lying just outside the groove and in the remaining three (5.8%) it was in a remote position with a positive Popeye Sign. A dynamic ultrasound scan revealed that the tenotomised tendons had adhered to the surrounding tissues (autotenodesis).The initial condition of the tendon influenced its final position (p < 0.0005). The presence of a Popeye sign was statistically influenced by the pre-operative co-existence of supraspinatus and subscapularis tears (p < 0.0001).

It appears that the natural history of the tenotomised long head of biceps tendon is to tenodese itself inside or just outside the bicipital groove, while its pre-operative condition and coexistent subscapularis tears play a significant role in the occurrence of a Popeye sign.


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 10 | Pages 1356 - 1361
1 Oct 2012
Streit MR Walker T Bruckner T Merle C Kretzer JP Clarius M Aldinger PR Gotterbarm T

The Oxford mobile-bearing unicompartmental knee replacement (UKR) is an effective and safe treatment for osteoarthritis of the medial compartment. The results in the lateral compartment have been disappointing due to a high early rate of dislocation of the bearing. A series using a newly designed domed tibial component is reported.

The first 50 consecutive domed lateral Oxford UKRs in 50 patients with a mean follow-up of three years (2.0 to 4.3) were included. Clinical scores were obtained prospectively and Kaplan-Meier survival analysis was performed for different endpoints. Radiological variables related to the position and alignment of the components were measured.

One patient died and none was lost to follow-up. The cumulative incidence of dislocation was 6.2% (95% confidence interval (CI) 2.0 to 17.9) at three years. Survival using revision for any reason and aseptic revision was 94% (95% CI 82 to 98) and 96% (95% CI 85 to 99) at three years, respectively. Outcome scores, visual analogue scale for pain and maximum knee flexion showed a significant improvement (p < 0.001). The mean Oxford knee score was 43 (sd 5.3), the mean Objective American Knee Society score was 91 (sd 13.9) and the mean Functional American Knee Society score was 90 (sd 17.5). The mean maximum flexion was 127° (90° to 145°). Significant elevation of the lateral joint line as measured by the proximal tibial varus angle (p = 0.04) was evident in the dislocation group when compared with the non-dislocation group.

Clinical results are excellent and short-term survival has improved when compared with earlier series. The risk of dislocation remains higher using a mobile-bearing UKR in the lateral compartment when compared with the medial compartment. Patients should be informed about this complication. To avoid dislocations, care must be taken not to elevate the lateral joint line.


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 4 | Pages 483 - 487
1 Apr 2012
Prosser GH Shears E O’Hara JN

The painful subluxed or dislocated hip in adults with cerebral palsy presents a challenging problem. Prosthetic dislocation and heterotopic ossification are particular concerns. We present the first reported series of 19 such patients (20 hips) treated with hip resurfacing and proximal femoral osteotomy. The pre-operative Gross Motor Function Classification System (GMFCS) was level V in 13 (68%) patients, level IV in three (16%), level III in one (5%) and level II in two (11%). The mean age at operation was 37 years (13 to 57).

The mean follow-up was 8.0 years (2.7 to 11.6), and 16 of the 18 (89%) contactable patients or their carers felt that the surgery had been worthwhile. Pain was relieved in 16 of the 18 surviving hips (89%) at the last follow-up, and the GMFCS level had improved in seven (37%) patients. There were two (10%) early dislocations; three hips (15%) required revision of femoral fixation, and two hips (10%) required revision, for late traumatic fracture of the femoral neck and extra-articular impingement, respectively. Hence there were significant surgical complications in a total of seven hips (35%). No hips required revision for instability, and there were no cases of heterotopic ossification.

We recommend hip resurfacing with proximal femoral osteotomy for the treatment of the painful subluxed or dislocated hip in patients with cerebral palsy.


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 11 | Pages 1550 - 1555
1 Nov 2011
Hill RA Ibrahim T Mann HA Siapkara A

We present our experience of forearm lengthening in children with various conditions performed by a single surgeon between 1995 and 2009. A total of 19 children with a mean age of 9.8 years (2.1 to 15.9) at the time of surgery had 22 forearm lengthenings using either an Ilizarov/spatial and Ilizarov circular frame or a monolateral external fixator. The patients were divided into two groups: group A, in whom the purpose of treatment was to restore the relationship between the radius and the ulna, and group B, in whom the objective was to gain forearm length. The mean follow-up after removal of the frame was 26 months (13 to 53).

There were ten patients (11 forearms) in group A with a mean radioulnar discrepancy of 2.4 cm (1.5 to 3.3) and nine patients (11 forearms) in group B. In group A, the mean lengthening achieved was 2.7 cm (1.0 to 5.5), with a lengthening index of 11.1 weeks/cm. Equalisation or overcorrection of the discrepancy was achieved in seven of 11 forearms, but lengthening was only partially successful at preventing subluxation or dislocation of the radial head. In group B, the mean lengthening achieved was 3.8 cm (1.9 to 6.8), with a lengthening index of 7.25 weeks/cm. Common complications in both groups were pin-site infection and poor regenerate formation.

Forearm lengthening by distraction osteogenesis is a worthwhile procedure in children that can improve cosmesis and function, particularly in patients with shortening of both radius and ulna.


The Journal of Bone & Joint Surgery British Volume
Vol. 93-B, Issue 2 | Pages 198 - 204
1 Feb 2011
Pandit H Jenkins C Gill HS Barker K Dodd CAF Murray DW

This prospective study describes the outcome of the first 1000 phase 3 Oxford medial unicompartmental knee replacements (UKRs) implanted using a minimally invasive surgical approach for the recommended indications by two surgeons and followed up independently. The mean follow-up was 5.6 years (1 to 11) with 547 knees having a minimum follow-up of five years. At five years their mean Oxford knee score was 41.3 (sd 7.2), the mean American Knee Society Objective Score 86.4 (sd 13.4), mean American Knee Society Functional Score 86.1 (sd 16.6), mean Tegner activity score 2.8 (sd 1.1). For the entire cohort, the mean maximum flexion was 130° at the time of final review.

The incidence of implant-related re-operations was 2.9%; of these 29 re-operations two were revisions requiring revision knee replacement components with stems and wedges, 17 were conversions to a primary total knee replacement, six were open reductions for dislocation of the bearing, three were secondary lateral UKRs and one was revision of a tibial component. The most common reason for further surgical intervention was progression of arthritis in the lateral compartment (0.9%), followed by dislocation of the bearing (0.6%) and revision for unexplained pain (0.6%). If all implant-related re-operations are considered failures, the ten-year survival rate was 96% (95% confidence interval, 92.5 to 99.5). If only revisions requiring revision components are considered failures the ten-year survival rate is 99.8% (confidence interval 99 to 100).

This is the largest published series of UKRs implanted through a minimally invasive surgical approach and with ten-year survival data. The survival rates are similar to those obtained with a standard open approach whereas the function is better. This demonstrates the effectiveness and safety of a minimally invasive surgical approach for implanting the Oxford UKR.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 7 | Pages 1013 - 1016
1 Jul 2010
Walton MJ Isaacson Z McMillan D Hawkes R Atherton WG

We present the results of treatment of developmental dysplasia of the hip in infancy with the Pavlik harness using a United Kingdom screening programme with ultrasound-guided supervision. Initially, 128 consecutive hips in 77 patients were reviewed over a 40-month period; 123 of these were finally included in the study. The mean age of the patients at the start of treatment was five weeks (1 to 12). All hips were examined clinically and monitored with ultrasound scanning. Failure of treatment was defined as an inability to maintain reduction with the harness. All hips diagnosed with dysplasia or subluxation but not dislocation were managed successfully in the harness. There were 43 dislocated hips, of which 39 were reducible, but six failed treatment in the harness. There were four dislocated but irreducible hips which all failed treatment in the harness. One hip appeared to be successfully treated in the harness but showed persistent radiological dysplasia at 12 and 24 months. Grade 1 avascular necrosis was identified radiologically in three patients at 12 months.


The Journal of Bone & Joint Surgery British Volume
Vol. 92-B, Issue 3 | Pages 367 - 373
1 Mar 2010
Kendrick BJL Longino D Pandit H Svard U Gill HS Dodd CAF Murray DW Price AJ

The Oxford Unicompartmental Knee replacement (UKR) was introduced as a design to reduce polyethylene wear. There has been one previous retrieval study involving this implant, which reported very low rates of wear in some specimens but abnormal patterns of wear in others. There has been no further investigation of these abnormal patterns. The bearings were retrieved from 47 patients who had received a medial Oxford UKR for anteromedial osteoarthritis of the knee. None had been studied previously. The mean time to revision was 8.4 years (sd 4.1), with 20 having been implanted for over ten years. The macroscopic pattern of polyethylene wear and the linear penetration were recorded for each bearing. The mean rate of linear penetration was 0.07 mm/year. The patterns of wear fell into three categories, each with a different rate of linear penetration; 1) no abnormal macroscopic wear and a normal articular surface, n = 16 (linear penetration rate = 0.01 mm/year); 2) abnormal macroscopic wear and normal articular surfaces with extra-articular impingement, n = 16 (linear penetration rate = 0.05 mm/year); 3) abnormal macroscopic wear and abnormal articular surfaces with intra-articular impingement +/− signs of non-congruous articulation, n = 15 (linear penetration rate = 0.12 mm/year). The differences in linear penetration rate were statistically significant (p < 0.001).

These results show that very low rates of polyethylene wear are possible if the device functions normally. However, if the bearing displays suboptimal function (extra-articular, intra-articular impingement or incongruous articulation) the rates of wear increase significantly.