Aims. In patients with a rotator cuff tear, tear pattern and tendon involvement are known risk factors for the development of pseudoparalysis of the shoulder. It remains unclear, however, why similar tears often have very different functional consequences. The present study hypothesizes that individual shoulder anatomy, specifically the moment arms (MAs) of the rotator cuff (RC) and the deltoid muscle, as well as their relative recruitment during shoulder abduction, plays a central role in pseudoparalysis. Materials and Methods. Biomechanical and clinical analyses of the pseudoparalytic shoulder were conducted based on the ratio of the RC/deltoid MAs, which were used to define a novel anatomical descriptor called the Shoulder Abduction Moment (SAM) index. The SAM index is the ratio of the radii of two concentric spheres based on the centre of rotation of the joint. One sphere captures the humeral head (numerator) and the other the deltoid origin of the acromion (denominator). A computational rigid body simulation was used to establish the functional link between the SAM index and a potential predisposition for pseudoparalysis. A retrospective radiological validation study based on these measures was also undertaken using two cohorts with and without pseudoparalysis and massive RC tears. Results. Decreased RC activity and improved glenohumeral stability was predicted by simulations of SAM indices with larger diameters of the humeral head, being consequently beneficial for joint stability. Clinical investigation of the SAM index showed significant risk of pseudoparalysis in patients with massive tears and a SAM < 0.77 (odds ratio (OR) 11). Conclusion. The SAM index, which represents individual biomechanical characteristics of shoulder morphology, plays a determinant role in the presence or absence of pseudoparalysis in shoulders with massive RC tears

Aims. It may not be possible to undertake revision total hip arthroplasty (THA) in the presence of massive loss of acetabular bone stock using standard cementless hemispherical acetabular components and metal augments, as satisfactory stability cannot always be achieved. We aimed to study the outcome using a reconstruction cage and a porous metal augment in these patients. Patients and Methods. A total of 22 acetabular revisions in 19 patients were performed using a combination of a reconstruction cage and porous metal augments. The augments were used in place of structural allografts. The mean age of the patients at the time of surgery was 70 years (27 to 85) and the mean follow-up was 39 months (27 to 58). The mean number of previous THAs was 1.9 (1 to 3). All patients had segmental defects involving more than 50% of the acetabulum and seven hips had an associated pelvic discontinuity. . Results. Three failures were observed in two hips, both of which had undergone a previous resection of a tumour affecting the acetabulum. Other complications included a late arterial injury, a sciatic nerve palsy, a dislocation treated with a femoral revision, a deep infection treated with irrigation and debridement and a fracture of the greater trochanter treated conservatively. The mean Oxford Hip Score significantly increased from 13.9 (2 to 23) to 28.7 (13 to 38) (p < 0.00001). The mean vertical distance between the centre of rotation of the hip and its normal location decreased from 30 mm to 10 mm. Conclusions. Acceptable early survivorship can be achieved using this novel technique, but it may be unsuitable for use in patients who have previously undergone the resection of a tumour involving the acetabulum. Cite this article: Bone Joint J 2017;99-B:607–13

We evaluated the accuracy with which a custom-made acetabular component could be positioned at revision arthroplasty of the hip in patients with a Paprosky type 3 acetabular defect. A total of 16 patients with a Paprosky type 3 defect underwent revision surgery using a custom-made trabecular titanium implant. There were four men and 12 women with a median age of 67 years (48 to 79). The planned inclination (INCL), anteversion (AV), rotation and centre of rotation (COR) of the implant were compared with the post-operative position using CT scans. A total of seven implants were malpositioned in one or more parameters: one with respect to INCL, three with respect to AV, four with respect to rotation and five with respect to the COR. To the best of our knowledge, this is the first study in which CT data acquired for the pre-operative planning of a custom-made revision acetabular implant have been compared with CT data on the post-operative position. The results are encouraging. Cite this article: Bone Joint J 2015; 97-B:780–5

The accurate reconstruction of hip anatomy and biomechanics is thought to be important in achieveing good clinical outcomes following total hip arthroplasty (THA). To this end some newer hip designs have introduced further modularity into the design of the femoral component such that neck­shaft angle and anteversion, which can be adjusted intra-operatively. The clinical effect of this increased modularity is unknown. We have investigated the changes in these anatomical parameters following conventional THA with a prosthesis of predetermined neck–shaft angle and assessed the effect of changes in the hip anatomy on clinical outcomes. . In total, 44 patients (mean age 65.3 years (standard deviation (. sd. ) 7); 17 male/27 female; mean body mass index 26.9 (kg/m²) (. sd. 3.1)) underwent a pre- and post-operative three-dimensional CT scanning of the hip. The pre- and post-operative neck–shaft angle, offset, hip centre of rotation, femoral anteversion, and stem alignment were measured. Additionally, a functional assessment and pain score were evaluated before surgery and at one year post-operatively and related to the post-operative anatomical changes. The mean pre-operative neck–shaft angle was significantly increased by 2.8° from 128° (. sd.  6.2; 119° to 147°) to 131° (. sd. 2.1; 127° to 136°) (p = 0.009). The mean pre-operative anteversion was 24.9° (. sd. 8; 7.9 to 39.1) and reduced to 7.4° (. sd. 7.3; -11.6° to 25.9°) post-operatively (p < 0.001). The post-operative changes had no influence on function and pain. Using a standard uncemented femoral component, high pre- and post-operative variability of femoral anteversion and neck–shaft angles was found with a significant decrease of the post-operative anteversion and slight increase of the neck–shaft angles, but without any impact on clinical outcome. Cite this article: Bone Joint J 2015;97-B:1615–22

The ‘jumbo’ acetabular component is now commonly used in acetabular revision surgery where there is extensive bone loss. It offers high surface contact, permits weight bearing over a large area of the pelvis, the need for bone grafting is reduced and it is usually possible to restore centre of rotation of the hip. Disadvantages of its use include a technique in which bone structure may not be restored, a risk of excessive posterior bone loss during reaming, an obligation to employ screw fixation, limited bone ingrowth with late failure and high hip centre, leading to increased risk of dislocation. Contraindications include unaddressed pelvic dissociation, inability to implant the component with a rim fit, and an inability to achieve screw fixation. Use in acetabulae with < 50% bone stock has also been questioned. Published results have been encouraging in the first decade, with late failures predominantly because of polyethylene wear and aseptic loosening. Dislocation is the most common complication of jumbo acetabular revisions, with an incidence of approximately 10%, and often mandates revision. Based on published results, a hemispherical component with an enhanced porous coating, highly cross-linked polyethylene, and a large femoral head appears to represent the optimum tribology for jumbo acetabular revisions. Cite this article: Bone Joint J 2016;98-B(1 Suppl A):64–7

Trabecular metal (TM) augments are a relatively new option for reconstructing segmental bone loss during acetabular revision. We studied 34 failed hip replacements in 34 patients that were revised between October 2003 and March 2010 using a TM acetabular shell and one or two augments. The mean age of the patients at the time of surgery was 69.3 years (46 to 86) and the mean follow-up was 64.5 months (27 to 107). In all, 18 patients had a minor column defect, 14 had a major column defect, and two were associated with pelvic discontinuity. The hip centre of rotation was restored in 27 patients (79.4%). The Oxford hip score increased from a mean of 15.4 points (6 to 25) before revision to a mean of 37.7 (29 to 47) at the final follow-up. There were three aseptic loosenings of the construct, two of them in the patients with pelvic discontinuity. One septic loosening also occurred in a patient who had previously had an infected hip replacement. The augments remained stable in two of the failed hips. Whenever there was a loose acetabular component in contact with a stable augment, progressive metal debris shedding was evident on the serial radiographs. Complications included another deep infection treated without revision surgery. Good clinical and radiological results can be expected for bone-deficient acetabula treated by a TM cup and augment, but for pelvic discontinuities this might not be a reliable option. Cite this article: Bone Joint J 2013;95-B:166–72

Reversed shoulder prostheses are increasingly being used for the treatment of glenohumeral arthropathy associated with a deficient rotator cuff. These non-anatomical implants attempt to balance the joint forces by means of a semi-constrained articular surface and a medialised centre of rotation. A finite element model was used to compare a reversed prosthesis with an anatomical implant. Active abduction was simulated from 0° to 150° of elevation. With the anatomical prosthesis, the joint force almost reached the equivalence of body weight. The joint force was half this for the reversed prosthesis. The direction of force was much more vertically aligned for the reverse prosthesis, in the first 90° of abduction. With the reversed prosthesis, abduction was possible without rotator cuff muscles and required 20% less deltoid force to achieve it. This force analysis confirms the potential mechanical advantage of reversed prostheses when rotator cuff muscles are deficient

The combination of an irreparable tear of the rotator cuff and destructive arthritis of the shoulder joint may cause severe pain, disability and loss of independence in the aged. Standard anatomical shoulder replacements depend on a functioning rotator cuff, and hence may fail in the presence of tears in the cuff. Many designs of non-anatomical constrained or semi-constrained prostheses have been developed for cuff tear arthropathy, but have proved unsatisfactory and were abandoned. The DePuy Delta III reverse prosthesis, designed by Grammont, medialises and stabilises the centre of rotation of the shoulder joint and has shown early promise. This study evaluated the mid-term clinical and radiological results of this arthroplasty in a consecutive series of 50 shoulders in 43 patients with a painful pseudoparalysis due to an irreparable cuff tear and destructive arthritis, performed over a period of seven years by a single surgeon. A follow-up of 98% was achieved, with a mean duration of 39 months (8 to 81). The mean age of the patients at the time of surgery was 81 years (59 to 95). The female to male ratio was 5:1. During the seven years, six patients died of natural causes. The clinical outcome was assessed using the American Shoulder and Elbow score, the Oxford Shoulder Score and the Short-form 36 score. A radiological review was performed using the Sirveaux score for scapular notching. The mean American Shoulder and Elbow score was 19 (95% confidence interval (CI) 14 to 23) pre-operatively, and 65 (95% CI 48 to 82) (paired t-test, p < 0.001) at final follow-up. The mean Oxford score was 44 (95% CI 40 to 51) pre-operatively and 23 (95% CI 18 to 28) (paired t-test, p < 0.001) at final follow-up. The mean maximum elevation improved from 55° pre-operatively to 105° at final follow-up. There were seven complications during the whole series, although only four patients required further surgery

Aims. Hip arthroplasty does not always restore normal anatomy. This is due to inaccurate surgery or lack of stem sizes. We evaluated the aptitude of four total hip arthroplasty systems to restore an anatomical and medialized hip rotation centre. Methods. Using 3D templating software in 49 CT scans of non-deformed femora, we virtually implanted: 1) small uncemented calcar-guided stems with two offset options (Optimys, Mathys), 2) uncemented straight stems with two offset options (Summit, DePuy Synthes), 3) cemented undersized stems (Exeter philosophy) with three offset options (CPT, ZimmerBiomet), and 4) cemented line-to-line stems (Kerboul philosophy) with proportional offsets (Centris, Mathys). We measured the distance between the templated and the anatomical and 5 mm medialized hip rotation centre. Results. Both rotation centres could be restored within 5 mm in 94% and 92% of cases, respectively. The cemented undersized stem performed best, combining freedom of stem positioning and a large offset range. The uncemented straight stem performed well because of its large and well-chosen offset range, and despite the need for cortical bone contact limiting stem positioning. The cemented line-to-line stem performed less well due to a small range of sizes and offsets. The uncemented calcar-guided stem performed worst, despite 24 sizes and a large and well-chosen offset range. This was attributed to the calcar curvature restricting the stem insertion depth along the femoral axis. Conclusion. In the majority of non-deformed femora, leg length, offset, and anteversion can be restored accurately with non-modular stems during 3D templating. Failure to restore hip biomechanics is mostly due to surgical inaccuracy. Small calcar guided stems offer no advantage to restore hip biomechanics compared to more traditional designs. Cite this article: Bone Jt Open 2021;2(7):476–485

We have reviewed 54 patients who had undergone 61 total hip replacements using bulk femoral autografts to augment a congenitally dysplastic acetabulum. There were 52 women and two men with a mean age of 42.4 years (29 to 76) at the time of the index operation. A variety of different prostheses was used: 28 (45.9%) were cemented and 33 (54.1%) uncemented. The graft technique remained unchanged throughout the series. Follow-up was at a mean of 8.3 years (3 to 20). The Hospital for Special Surgery hip score improved from a mean of 10.7 (4 to 18) pre-operatively to a mean of 35 (28 to 38) at follow-up. The position of the acetabular component was anatomical in 37 hips (60.7%), displaced less than 1 cm in 20 (32.7%) and displaced more than 1 cm in four (6.6%). Its cover was between 50% and 75% in 34 hips (55.7%) and less than 50% in 25 (41%). In two cases (3.3%), it was more than 75%. There was no graft resorption in 36 hips (59%), mild resorption in 21 (34%) and severe resorption in four (6%). Six hips (9.8%) were revised for aseptic loosening. The overall rate of loosening and revision was 14.8%. Overall survival at 8.3 years was 93.4%. The only significant factor which predicted failure was the implantation of the acetabular component more than 1 cm from the anatomical centre of rotation of the hip

We analysed one surgeon’s attempt to reconstruct the hip in 66 patients (84 hips) with chronic dislocation and to restore the height of the centre of rotation above the transverse teardrop line, the bodyweight lever arm, the abductor lever arm, and the abductor angle to normal. The outcome was assessed using a patient profile at 0, 10 and 20 years, a clinical assessment of pain, mobility and the range of active movement. We measured the work done by active movement against gravity, radiological signs of loosening, migration and subsidence, and the need for revision. We used survival at ten years and revision as the endpoint. The incidence of complications was higher than in arthroplasty for primary osteoarthritis of the hip, but the outcome was considered satisfactory. The advantages of a flanged cemented socket were demonstrated. A custom-made, laterally reduced, Charnley extra small CDH femoral prosthesis was used in certain cases

Aims

The primary objective of this study was to develop a validated classification system for assessing iatrogenic bone trauma and soft-tissue injury during total hip arthroplasty (THA). The secondary objective was to compare macroscopic bone trauma and soft-tissues injury in conventional THA (CO THA) versus robotic arm-assisted THA (RO THA) using this classification system.

To analyse the value and accuracy of preoperative planning for total hip replacement (THR) we digitised electronically and compared the hand-sketched preoperative plans with the pre- and postoperative radiographs of 100 consecutive primary THRs. The correct type of prosthesis was planned in 98%; the agreement between planned and actually used components was 92% on the femoral side and 90% on the acetabular side. The mean (± SD) absolute difference between the planned and actual position of the centre of rotation of the hip was 2.5 ± 1.1 mm vertically and 4.4 ± 2.1 mm horizontally. On average, the inclination of the acetabular component differed by 7 ± 2° and anteversion by 9 ± 3° from the preoperative plans. The mean postoperative leg-length difference was 0.3 ± 0.1 cm clinically and 0.2 ± 0.1 cm radiologically. More than 80% of intraoperative difficulties were anticipated. Preoperative planning is of significant value for the successful performance of THR

Aims

To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time.

Aims

Pelvic discontinuity is a challenging acetabular defect without a consensus on surgical management. Cup-cage reconstruction is an increasingly used treatment strategy. The present study evaluated implant survival, clinical and radiological outcomes, and complications associated with the cup-cage construct.

Aims

Large bone defects resulting from osteolysis, fractures, osteomyelitis, or metastases pose significant challenges in acetabular reconstruction for total hip arthroplasty. This study aimed to evaluate the survival and radiological outcomes of an acetabular reconstruction technique in patients at high risk of reconstruction failure (i.e. periprosthetic joint infection (PJI), poor bone stock, immunosuppressed patients), referred to as Hip Reconstruction In Situ with Screws and Cement (HiRISC). This involves a polyethylene liner embedded in cement-filled bone defects reinforced with screws and/or plates for enhanced fixation.

Aims

Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data.

Aims

Pelvic discontinuity is a rare but increasingly common complication of total hip arthroplasty (THA). This single-centre study evaluated the performance of custom-made triflange acetabular components in acetabular reconstruction with pelvic discontinuity by determining: 1) revision and overall implant survival rates; 2) discontinuity healing rate; and 3) Harris Hip Score (HHS).

Aims

The use of a porous metal shell supported by two augments with the ‘footing’ technique is one solution to manage Paprosky IIIB acetabular defects in revision total hip arthroplasty. The aim of this study was to assess the medium-term implant survival and radiological and clinical outcomes of this technique.