The April 2013 Wrist & Hand Roundup³⁶⁰ looks at: whether botox is just for Hollywood; supercharging nerve repairs; YouTube research; options for Keinbock’s disease; volar plates; driving and plasters; symptomatic radial malunion; and MRI and acute scaphoid fractures.

We investigated whether an asymmetric extension gap seen on routine post-operative radiographs after primary total knee replacement (TKR) is associated with pain at three, six, 12 and 24 months’ follow-up. On radiographs of 277 patients after primary TKR we measured the distance between the tibial tray and the femoral condyle on both the medial and lateral sides. A difference was defined as an asymmetric extension gap. We considered three groups (no asymmetric gap, medial-opening and lateral-opening gap) and calculated the associations with the Western Ontario and McMaster Universities osteoarthritis index pain scores over time.

Those with an asymmetric extension gap of ≥ 1.5 mm had a significant association with pain scores at three months’ follow-up; patients with a medial-opening extension gap reported more pain and patients with a lateral-opening extension gap reported less pain (p = 0.036). This effect was still significant at six months (p = 0.044), but had lost significance by 12 months (p = 0.924). When adjusting for multiple cofounders the improvement in pain was more pronounced in patients with a lateral-opening extension gap than in those with a medial-opening extension gap at three (p = 0.037) and six months’ (p = 0.027) follow-up.

Cite this article: Bone Joint J 2013;95-B:472–7.

Deficiency of the abductor mechanism is a well-recognised cause of pain and limping after total hip replacement (THR). This can be found incidentally at the time of surgery, or it may arise as a result of damage to the superior gluteal nerve intra-operatively, or after surgery owing to mechanical failure of the abductor muscle repair or its detachment from the greater trochanter. The incidence of abductor failure has been reported as high as 20% in some studies. The management of this condition remains a dilemma for the treating surgeon. We review the current state of knowledge concerning post-THR abductor deficiency, including the aetiology, diagnosis and management, and the outcomes of surgery for this condition.

Cite this article: Bone Joint J 2013;95-B:343–7.

Recently, gender-specific designs of total knee replacement have been developed to accommodate anatomical differences between males and females. We examined a group of male and female distal femora matched for age and height, to determine if there was a difference in the aspect ratio (mediolateral distance versus anteroposterior distance) and the height of the anterior flange between the genders. The Hamann-Todd Collection provided 1207 skeletally mature cadaver femora. The femoral length, the anteroposterior height, height of the lateral and medial flanges and the mediolateral width were measured in all the specimens. The mechanical axis of the femur, the cut articular width and the aspect ratio were assessed. Statistical analysis of the effect of gender upon the aspect ratio and the lateral and medial flanges was undertaken, controlling for age, height and race.

The mean aspect ratio of male femora was 1.21 (sd 0.07) and of female femora it was 1.16 (sd 0.06) (p < 0.001). There was no significant difference between male and female specimens in the mean size of the lateral flange (6.57 mm (sd 2.57) and 7.02 mm (sd 2.36), respectively; p = 0.099) or of the medial flange (3.03 mm (sd 2.47) and 3.56 mm (sd 2.32), respectively; p = 0.67). Future work in the design of knee prostheses should take into account the overall variability of the anatomy of the distal femur.

Large femoral heads have been used with increasing frequency over the last decade. The prime reason is likely the effect of large heads on stability. The larger head neck ratio, combined with the increased jump distance of larger heads result in a greater arc of impingement free motion, and greater resistance to dislocation in a provocative position. Multiple studies have demonstrated clear clinical efficacy in diminishing dislocation rates with the use of large femoral heads. With crosslinked polyethylene, wear has been shown to be equivalent between larger and smaller heads. However, the stability advantages of increasing diameter beyond 38 mm have not been clearly demonstrated. More importantly, recent data implicates large heads in the increasing prevalence of groin pain and psoas impingement. There are clear benefits with larger femoral head diameters, but the advantages of diameters beyond 38 mm have not yet been demonstrated clinically.

Reverse total shoulder replacement (RTSR) depends on adequate deltoid function for a successful outcome. However, the anterior deltoid and/or axillary nerve may be damaged due to prior procedures or injury. The purpose of this study was to determine the compensatory muscle forces required for scapular plane elevation following RTSR when the anterior deltoid is deficient. The soft tissues were removed from six cadaver shoulders, except for tendon attachments. After implantation of the RTSR, the shoulders were mounted on a custom-made shoulder simulator to determine the mean force in each muscle required to achieve 30° and 60° of scapular plane elevation. Two conditions were tested: 1) Control with an absent supraspinatus and infraspinatus; and 2) Control with anterior deltoid deficiency. Anterior deltoid deficiency resulted in a mean increase of 195% in subscapularis force at 30° when compared with the control (p = 0.02). At 60°, the subscapularis force increased a mean of 82% (p < 0.001) and the middle deltoid force increased a mean of 26% (p = 0.04).

Scapular plane elevation may still be possible following an RTSR in the setting of anterior deltoid deficiency. When the anterior deltoid is deficient, there is a compensatory increase in the force required by the subscapularis and middle deltoid. Attempts to preserve the subscapularis, if present, might maximise post-operative function.

This study provides recommendations on the position of the implant in reverse shoulder replacement in order to minimise scapular notching and osteophyte formation. Radiographs from 151 patients who underwent primary reverse shoulder replacement with a single prosthesis were analysed at a mean follow-up of 28.3 months (24 to 44) for notching, osteophytes, the position of the glenoid baseplate, the overhang of the glenosphere, and the prosthesis scapular neck angle (PSNA).

A total of 20 patients (13.2%) had a notch (16 Grade 1 and four Grade 2) and 47 (31.1%) had an osteophyte. In patients without either notching or an osteophyte the baseplate was found to be positioned lower on the glenoid, with greater overhang of the glenosphere and a lower PSNA than those with notching and an osteophyte. Female patients had a higher rate of notching than males (13.3% vs 13.0%) but a lower rate of osteophyte formation (22.9% vs 50.0%), even though the baseplate was positioned significantly lower on the glenoid in females (p = 0.009) and each had a similar mean overhang of the glenosphere.

Based on these findings we make recommendations on the placement of the implant in both male and female patients to avoid notching and osteophyte formation.

Cite this article: Bone Joint J 2013;95-B:530–5.

The Cementless Oxford Unicompartmental Knee Replacement (OUKR) was developed to address problems related to cementation, and has been demonstrated in a randomised study to have similar clinical outcomes with fewer radiolucencies than observed with the cemented device. However, before its widespread use it is necessary to clarify contraindications and assess the complications. This requires a larger study than any previously published.

We present a prospective multicentre series of 1000 cementless OUKRs in 881 patients at a minimum follow-up of one year. All patients had radiological assessment aligned to the bone–implant interfaces and clinical scores. Analysis was performed at a mean of 38.2 months (19 to 88) following surgery. A total of 17 patients died (comprising 19 knees (1.9%)), none as a result of surgery; there were no tibial or femoral loosenings. A total of 19 knees (1.9%) had significant implant-related complications or required revision. Implant survival at six years was 97.2%, and there was a partial radiolucency at the bone–implant interface in 72 knees (8.9%), with no complete radiolucencies. There was no significant increase in complication rate compared with cemented fixation (p = 0.87), and no specific contraindications to cementless fixation were identified.

Cementless OUKR appears to be safe and reproducible in patients with end-stage anteromedial osteoarthritis of the knee, with radiological evidence of improved fixation compared with previous reports using cemented fixation.

Cite this article: Bone Joint J 2013;95-B:181–7.

Objectives

The effects of disease progression and common tendinopathy treatments on the tissue characteristics of human rotator cuff tendons have not previously been evaluated in detail owing to a lack of suitable sampling techniques. This study evaluated the structural characteristics of torn human supraspinatus tendons across the full disease spectrum, and the short-term effects of subacromial corticosteroid injections (SCIs) and subacromial decompression (SAD) surgery on these structural characteristics.

The purpose of this study was to compare the amount of acetabular bone removed during hip resurfacing (HR) and cementless total hip replacement (THR), after controlling for the diameter of the patient’s native femoral head. Based on a power analysis, 64 consecutive patients (68 hips) undergoing HR or THR were prospectively enrolled in the study. The following data were recorded intra-operatively: the diameter of the native femoral head, the largest reamer used, the final size of the acetabular component, the size of the prosthetic femoral head and whether a decision was made to increase the size of the acetabular component in order to accommodate a larger prosthetic femoral head. Results were compared using two-sided, independent samples Student’s t-tests. A statistically significant difference was seen in the mean ratio of the size of the acetabular component to the diameter of the native femoral head (HR: 1.05 (sd 0.04) versus THR: 1.09 (sd 0.05); p <  0.001) and largest acetabular reamer used to the diameter of the native femoral head (HR: 1.03 (sd 0.04) versus THR: 1.09 (sd 0.05); p < 0.001). The ratios varied minimally when the groups were subdivided by gender, age and obesity. The decision to increase the size of the acetabular component to accommodate a larger femoral head occurred more often in the THR group (27% versus 9%). Despite the emphasis on avoiding damage to the femoral neck during HR, the ratio of the size of the acetabular component to the diameter of the native femoral head was larger in cementless THR than in HR.

In a study on ten fresh human cadavers we examined the change in the height of the intervertebral disc space, the angle of lordosis and the geometry of the facet joints after insertion of intervertebral total disc replacements. SB III Charité prostheses were inserted at L3-4, L4-5, and L5-S1. The changes studied were measured using computer navigation sofware applied to CT scans before and after instrumentation.

After disc replacement the mean lumbar disc height was doubled (p < 0.001). The mean angle of lordosis and the facet joint space increased by a statistically significant extent (p < 0.005 and p = 0.006, respectively). By contrast, the mean facet joint overlap was significantly reduced (p < 0.001). Our study indicates that the increase in the intervertebral disc height after disc replacement changes the geometry at the facet joints. This may have clinical relevance.

A delay in establishing the diagnosis of an occult fracture of the hip that remains unrecognised after plain radiography can result in more complex treatment such as an arthroplasty being required. This might be avoided by earlier diagnosis using MRI. The aim of this study was to investigate the best MR imaging sequence for diagnosing such fractures. From a consecutive cohort of 771 patients admitted between 2003 and 2011 with a clinically suspected fracture of the hip, we retrospectively reviewed the MRI scans of the 35 patients who had no evidence of a fracture on their plain radiographs. In eight of these patients MR scanning excluded a fracture but the remaining 27 patients had an abnormal scan: one with a fracture of the pubic ramus, and in the other 26 a T₁-weighted coronal MRI showed a hip fracture with 100% sensitivity. T₂-weighted imaging was undertaken in 25 patients, in whom the diagnosis could not be established with this scanning sequence alone, giving a sensitivity of 84.0% for T₂-weighted imaging.

If there is a clinical suspicion of a hip fracture with normal radiographs, T₁-weighted coronal MRI is the best sequence of images for identifying a fracture.

This article reviews the current knowledge of the intervertebral disc (IVD) and its association with low back pain (LBP). The normal IVD is a largely avascular and aneural structure with a high water content, its nutrients mainly diffusing through the end plates. IVD degeneration occurs when its cells die or become dysfunctional, notably in an acidic environment. In the process of degeneration, the IVD becomes dehydrated and vascularised, and there is an ingrowth of nerves. Although not universally the case, the altered physiology of the IVD is believed to precede or be associated with many clinical symptoms or conditions including low back and/or lower limb pain, paraesthesia, spinal stenosis and disc herniation.

New treatment options have been developed in recent years. These include biological therapies and novel surgical techniques (such as total disc replacement), although many of these are still in their experimental phase. Central to developing further methods of treatment is the need for effective ways in which to assess patients and measure their outcomes. However, significant difficulties remain and it is therefore an appropriate time to be further investigating the scientific basis of and treatment of LBP.

Bone loss involving articular surface is a challenging problem faced by the orthopaedic surgeon. In the hand and wrist, there are articular defects that are amenable to autograft reconstruction when primary fixation is not possible. In this article, the surgical techniques and clinical outcomes of articular reconstructions in the hand and wrist using non-vascularised osteochondral autografts are reviewed.

Objectives

There remains a lack of data on the reliability of methods to estimate tibial coverage achieved during total knee replacement. In order to address this gap, the intra- and interobserver reliability of a three-dimensional (3D) digital templating method was assessed with one symmetric and one asymmetric prosthesis design.

The aim of this study was to determine the accuracy of registration and the precision of the resection volume in navigated hip arthroscopy for cam-type femoroacetabular impingement, using imageless and image-based registration. A virtual cam lesion was defined in 12 paired cadaver hips and randomly assigned to either imageless or image-based (three-dimensional (3D) fluoroscopy) navigated arthroscopic head–neck osteochondroplasty. The accuracy of patient–image registration for both protocols was evaluated and post-operative imaging was performed to evaluate the accuracy of the surgical resection. We found that the estimated accuracy of imageless registration in the arthroscopic setting was poor, with a mean error of 5.6 mm (standard deviation (sd) 4.08; 95% confidence interval (CI) 4.14 to 7.19). Because of the significant mismatch between the actual position of the probe during surgery and the position of that probe as displayed on the navigation platform screen, navigated femoral osteochondroplasty was physically impossible. The estimated accuracy of image-based registration by means of 3D fluoroscopy had a mean error of 0.8 mm (sd 0.51; 95% CI 0.56 to 0.94). In terms of the volume of bony resection, a mean of 17% (sd 11; -6% to 28%) more bone was resected than with the virtual plan (p = 0.02). The resection was a mean of 1 mm deeper (sd 0.7; -0.3 to 1.6) larger than on the original virtual plan (p = 0.02).

In conclusion, given the limited femoral surface that can be reached and digitised during arthroscopy of the hip, imageless registration is inaccurate and does not allow for reliable surgical navigation. However, image-based registration does acceptably allow for guided femoral osteochondroplasty in the arthroscopic management of femoroacetabular impingement.

We describe a symptomatic, progressive restriction of knee flexion due to an accessory quadriceps femoris in a nine-year-old girl. There was no history or findings of post-injection fibrosis, nor any obvious swelling of the affected quadriceps. At arthroscopy no intra-articular pathology was found. An accessory ‘quinticeps femoris’ was diagnosed by ultrasonography and MRI. Following excision of the muscle and tendon full flexion of the knee was regained and there was no recurrence of the contracture.

We report a prospective analysis of clinical outcome in patients treated with medial patellofemoral ligament (MPFL) reconstruction using an autologous semitendinosus graft. The technique includes superolateral portal arthroscopic assessment before and after graft placement to ensure correct graft tension and patellar tracking before fixation. Between October 2005 and October 2010, a total of 201 consecutive patients underwent 219 procedures. Follow-up is presented for 211 procedures in 193 patients with a mean age of 26 years (16 to 49), and mean follow-up of 16 months (6 to 42). Indications were atraumatic recurrent patellar dislocation in 141 patients, traumatic recurrent dislocation in 50, pain with subluxation in 14 and a single dislocation with persistent instability in six. There have been no recurrent dislocations/subluxations. There was a statistically significant improvement between available pre- and post-operative outcome scores for 193 patients (all p < 0.001). Female patients with a history of atraumatic recurrent dislocation and all patients with history of previous surgery had a significantly worse outcome (all p < 0.05). The indication for surgery, degree of dysplasia, associated patella alta, time from primary dislocation to surgery and evidence of associated cartilage damage at operation did not result in any significant difference in outcome.

This series adds considerably to existing evidence that MPFL reconstruction is an effective surgical procedure for selected patients with patellofemoral instability.

The aim of this study was to compare a third-generation cementing procedure for glenoid components with a new technique for cement pressurisation. In 20 pairs of scapulae, 20 keeled and 20 pegged glenoid components were implanted using either a third-generation cementing technique (group 1) or a new pressuriser (group 2). Cement penetration was measured by three-dimensional (3D) analysis of micro-CT scans. The mean 3D depth of penetration of the cement was significantly greater in group 2 (p < 0.001). The mean thickness of the cement mantle for keeled glenoids was 2.50 mm (2.0 to 3.3) in group 1 and 5.18 mm (4.4 to 6.1) in group 2, and for pegged glenoids it was 1.72 mm (0.9 to 2.3) in group 1 and 5.63 mm (3.6 to 6.4) in group 2. A cement mantle < 2 mm was detected less frequently in group 2 (p < 0.001). Using the cement pressuriser the proportion of cement mantles < 2 mm was significantly reduced compared with the third-generation cementing technique.

Objectives

Cadaveric models of the shoulder evaluate discrete motion segments using the glenohumeral joint in isolation over a defined trajectory. The aim of this study was to design, manufacture and validate a robotic system to accurately create three-dimensional movement of the upper body and capture it using high-speed motion cameras.