Aims. To evaluate the outcomes of cemented total hip arthroplasty (THA) following a fracture of the acetabulum, with evaluation of risk factors and comparison with a patient group with no history of fracture. . Patients and Methods. Between 1992 and 2016, 49 patients (33 male) with mean age of 57 years (25 to 87) underwent cemented THA at a mean of 6.5 years (0.1 to 25) following acetabular fracture. A total of 38 had undergone surgical fixation and 11 had been treated non-operatively; 13 patients died at a mean of 10.2 years after THA (0.6 to 19). Patients were assessed pre-operatively, at one year and at final follow-up (mean 9.1 years, 0.5 to 23) using the Oxford Hip Score (OHS). Implant survivorship was assessed. An age and gender-matched cohort of THAs performed for non-traumatic osteoarthritis (OA) or avascular necrosis (AVN) (n = 98) were used to compare complications and patient-reported outcome measures (PROMs). Results. The mean time from fracture to THA was significantly shorter for patients with AVN (2.2 years) or protrusio (2.2 years) than those with post-traumatic OA (9.4 years) or infection (8.0 years) (p = 0.03). Nine contained and four uncontained defects were managed with autograft (n = 11), bulk allograft (n = 1), or trabecular metal augment (n = 1). Initial fracture management (open reduction and internal fixation or non-operative), timing of THA (> /< one year), and age (> /< 55 years) had no significant effect on OHS or ten-year survival. Six THAs were revised at mean of 12 years (5 to 23) with ten-year all-cause survival of 92% (95% confidence interval 80.8 to 100). THA complication rates (all complications, heterotopic ossification, leg length discrepancy > 10 mm) were significantly higher following acetabular fracture compared with atraumatic OA/AVN and OHSs were inferior: one-year OHS (35.7 versus 40.2, p = 0.026); and final follow-up OHS (33.6 versus 40.9, p = 0.008). . Conclusion . Cemented THA is a reasonable option for the sequelae of acetabular fracture. Higher complication rates and poorer PROMs, compared with patients undergoing THA for atraumatic causes, reflects the complex nature of these cases. Cite this article: Bone Joint J 2017;99-B:1399–1408

Aims

To explore staff experiences of a multicentre pilot randomized controlled trial (RCT) comparing intramedullary nails and circular frame external fixation for segmental tibial fractures.

Aims

We report the long-term outcomes of the UK Heel Fracture Trial (HeFT), a pragmatic, multicentre, two-arm, assessor-blinded, randomized controlled trial.

Aims

Complex joint fractures of the lower extremity are often accompanied by soft-tissue swelling and are associated with prolonged hospitalization and soft-tissue complications. The aim of the study was to evaluate the effect of vascular impulse technology (VIT) on soft-tissue conditioning in comparison with conventional elevation.

Aims

The primary aim of this study was to address the hypothesis that fracture morphology might be more important than posterior malleolar fragment size in rotational type posterior malleolar ankle fractures (PMAFs). The secondary aim was to identify clinically important predictors of outcome for each respective PMAF-type, to challenge the current dogma that surgical decision-making should be based on fragment size.

In Neer type II (Robinson type 3B) fractures of the distal clavicle the medial fragment is detached from the coracoclavicular ligaments and displaced upwards, whereas the lateral fragment, which is usually small, maintains its position. Several fixation techniques have been suggested to treat this fracture. The aim of this study was to assess the outcome of patients with type II distal clavicle fractures treated with coracoclavicular suture fixation using three loops of Ethibond. This prospective study included 14 patients with Neer type II fractures treated with open reduction and coracoclavicular fixation. Ethibond sutures were passed under the coracoid and around the clavicle (UCAC loop) without making any drill holes in the proximal or distal fragments. There were 11 men and three women with a mean age of 34.57 years (29 to 41). Patients were followed for a mean of 24.64 months (14 to 31) and evaluated radiologically and clinically using the Constant score. Fracture union was obtained in 13 patients at a mean of 18.23 weeks (13 to 23) and the mean Constant score was 96.07 (91 to 100). One patient developed an asymptomatic fibrous nonunion at one year. This study suggests that open reduction and internal fixation of unstable distal clavicle fractures using UCAC loops can provide rigid fixation and lead to bony union. This technique avoids using metal hardware, preserves the acromioclavicular joint and provides adequate stability with excellent results. Cite this article: Bone Joint J 2013;95-B:983–7

The treatment of infected exposed implants which have been used for internal fixation usually involves debridement and removal of the implant. This can result in an unstable fracture or spinal column. Muscle flaps may be used to salvage these implants since they provide soft-tissue cover and fresh vascularity. However, there have been few reports concerning their use and these have concentrated on the eradication of the infection and successful soft-tissue cover as the endpoint. There is no information on the factors which may influence the successful salvage of the implant using muscle flaps. We studied the results and factors affecting outcome in nine pedicled muscle flaps used in the treatment of exposed metal internal fixation with salvage of the implant as the primary endpoint. This was achieved in four cases. Factors predicting success were age < 30 years, the absence of comorbid conditions and a favourable microbiological profile. The growth of multiple organisms, a history of smoking and the presence of methicillin-resistant Staphylococcus aureus on wound cultures indicated a poor outcome. The use of antibiotic beads, vacuum-assisted closure and dressing, the surgical site, the type of flap performed and the time from primary surgery to flap cover were not predictive of outcome

Aims

This study assessed the association of classes of body mass index in kg/m² (classified as normal weight 18.5 kg/m² to 24.9 kg/m², overweight 25.0 kg/m² to 29.9 kg/m², and obese ≥ 30.0 kg/m²) with short-term complications and functional outcomes three to six years post-operatively for closed ankle fractures.

Aims

The aim of this study was to investigate the effect of a posterior malleolar fragment (PMF), with < 25% ankle joint surface, on pressure distribution and joint-stability. There is still little scientific evidence available to advise on the size of PMF, which is essential to provide treatment. To date, studies show inconsistent results and recommendations for surgical treatment date from 1940.

In the time since Letournel popularised the surgical treatment of acetabular fractures, more than 25 years ago, there have been many changes within the field, related to patients, surgical technique, implants and post-operative care. However, the long-term outcomes appear largely unchanged. Does this represent stasis or have the advances been mitigated by other negative factors? In this article we have attempted to document the recent changes within the surgery of patients with a fracture involving the acetabulum, outline contemporary management, and identify the major problem areas where further research is most needed.

Cite this article: Bone Joint J 2017;99-B:1125–31

Aims

The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) may improve quality of life for amputees by avoiding soft-tissue complications associated with socket prostheses and by improving sensory feedback and function. It relies on the formation of a seal between the soft tissues and the implant and currently has a flange with drilled holes to promote dermal attachment. Despite this, infection remains a significant risk. This study explored alternative strategies to enhance soft-tissue integration.

Objectives

Bisphosphonates are widely used as first-line treatment for primary and secondary prevention of fragility fractures. Whilst they have proved effective in this role, there is growing concern over their long-term use, with much evidence linking bisphosphonate-related suppression of bone remodelling to an increased risk of atypical subtrochanteric fractures of the femur (AFFs). The objective of this article is to review this evidence, while presenting the current available strategies for the management of AFFs.

It is becoming increasingly common for a patient to have ipsilateral hip and knee replacements. The inter-prosthetic (IP) distance, the distance between the tips of hip and knee prostheses, has been thought to be associated with an increased risk of IP fracture. Small gap distances are generally assumed to act as stress risers, although there is no real biomechanical evidence to support this.

The purpose of this study was to evaluate the influence of IP distance, cortical thickness and bone mineral density on the likelihood of an IP femoral fracture.

A total of 18 human femur specimens were randomised into three groups by bone density and cortical thickness. For each group, a defined IP distance of 35 mm, 80 mm or 160 mm was created by choosing the appropriate lengths of component. The maximum fracture strength was determined using a four-point bending test.

The fracture force of all three groups was similar (p = 0.498). There was a highly significant correlation between the cortical area and the fracture strength (r = 0.804, p <  0.001), whereas bone density showed no influence.

This study suggests that the IP distance has little influence on fracture strength in IP femoral fractures: the thickness of the cortex seems to be the decisive factor.

Cite this article: Bone Joint J 2014;96-B:1378–84.

This is a retrospective study of survivors of recent conflicts with an open fracture of the femur. We analysed the records of 48 patients (48 fractures) and assessed the outcome. The median follow up for 47 patients (98%) was 37 months (interquartile range 19 to 53); 31 (66%) achieved union; 16 (34%) had a revision procedure, two of which were transfemoral amputation (4%).

The New Injury Severity Score, the method of fixation, infection and the requirement for soft-tissue cover were not associated with a poor outcome. The degree of bone loss was strongly associated with a poor outcome (p = 0.00204). A total of four patients developed an infection; two with S. aureus, one with E. coli and one with A. baumannii.

This study shows that, compared with historical experience, outcomes after open fractures of the femur sustained on the battlefield are good, with no mortality and low rates of infection and late amputation. The degree of bone loss is closely associated with a poor outcome.

Cite this article: Bone Joint J 2015;97-B:842–6.

The Essex-Lopresti injury (ELI) of the forearm is a rare and serious condition which is often overlooked, leading to a poor outcome.

The purpose of this retrospective case study was to establish whether early surgery can give good medium-term results.

From a group of 295 patients with a fracture of the radial head, 12 patients were diagnosed with ELI on MRI which confirmed injury to the interosseous membrane (IOM) and ligament (IOL). They were treated by reduction and temporary Kirschner (K)-wire stabilisation of the distal radioulnar joint (DRUJ). In addition, eight patients had a radial head replacement, and two a radial head reconstruction.

All patients were examined clinically and radiologically 59 months (25 to 90) after surgery when the mean Mayo Modified Wrist Score (MMWS) was 88.4 (78 to 94), the mean Mayo Elbow Performance Scores (MEPS) 86.7 (77 to 95) and the mean disabilities of arm, shoulder and hand (DASH) score 20.5 (16 to 31): all of these indicate a good outcome.

In case of a high index of suspicion for ELI in patients with a radial head fracture, we recommend the following: confirmation of IOM and IOL injury with an early MRI scan; early surgery with reduction and temporary K-wire stabilisation of the DRUJ; preservation of the radial head if at all possible or replacement if not, and functional bracing in supination. This will increase the prospect of a good result, and avoid the complications of a missed diagnosis and the difficulties of late treatment.

Cite this article: Bone Joint J 2014;96-B:1385–91.

Objectives

Osteochondral injuries, if not treated adequately, often lead to severe osteoarthritis. Possible treatment options include refixation of the fragment or replacement therapies such as Pridie drilling, microfracture or osteochondral grafts, all of which have certain disadvantages. Only refixation of the fragment can produce a smooth and resilient joint surface. The aim of this study was the evaluation of an ultrasound-activated bioresorbable pin for the refixation of osteochondral fragments under physiological conditions.

Our aim was to compare polylevolactic acid screws with titanium screws when used for fixation of the distal tibiofibular syndesmosis at mid-term follow-up. A total of 168 patients, with a mean age of 38.5 years (18 to 72) who were randomly allocated to receive either polylevolactic acid (n = 86) or metallic (n = 82) screws were included. The Baird scoring system was used to assess the overall satisfaction and functional recovery post-operatively. The demographic details and characteristics of the injury were similar in the two groups. The mean follow-up was 55.8 months (48 to 66). The Baird scores were similar in the two groups at the final follow-up. Patients in the polylevolactic acid group had a greater mean dorsiflexion (p = 0.011) and plantar-flexion of the injured ankles (p < 0.001). In the same group, 18 patients had a mild and eight patients had a moderate foreign body reaction. In the metallic groups eight had mild and none had a moderate foreign body reaction (p <  0.001). In total, three patients in the polylevolactic acid group and none in the metallic group had heterotopic ossification (p = 0.246).

We conclude that both screws provide adequate fixation and functional recovery, but polylevolactic acid screws are associated with a higher incidence of foreign body reactions.

Cite this article: Bone Joint J 2014;96-B:548–54.

We report a prospective single-blind controlled study of the incidence of early wound infection after internal fixation for trauma in 609 patients, of whom 132 were HIV-positive. Wounds were assessed for healing using the ASEPSIS score. There was no significant difference in the rate of infection between HIV-positive and HIV-negative patients undergoing clean surgery (4.2% vs 6%, respectively; p = 0.65). HIV-positive patients did not receive additional antibiotic prophylaxis or antiretroviral therapy as part of their management. The difference in the rate of infection between HIV-positive and HIV-negative patients with an open fracture or other contamination was not significant (33% vs 15%, respectively; p = 0.064). There was no relationship between CD4 count and infection rate. HIV status did not significantly influence the number of secondary surgical procedures (p = 0.183) or the likelihood of developing chronic osteomyelitis (p = 0.131). Although previous contamination from the time of injury was a risk factor for infection in mal- and nonunions, it was not significantly increased in HIV-positive patients (p = 0.144).

We conclude that clean implant surgery in HIV-positive patients is safe, with no need for additional prophylaxis.

The extended lateral L-shaped approach for the treatment of displaced intra-articular fractures of the calcaneum may be complicated by wound infection, haematoma, dehiscence and injury to the sural nerve. In an effort to reduce the risk of problems with wound healing a technique was developed that combined open reduction and fixation of the joint fragments and of the anterior process with percutaneous reduction and screw fixation of the tuberosity. A group of 24 patients with unilateral isolated closed Sanders type II and III fractures was treated using this technique and compared to a similar group of 26 patients managed by the extended approach and lateral plating. The operation was significantly shorter (p < 0.001) in the first group, but more minor secondary procedures and removal of heel screws were necessary. There were no wound complications in this group, whereas four minor complications occurred in the second group. The accuracy and maintenance of reduction, and ultimate function were equivalent.

We treated 47 patients with a mean age of 57 years (22 to 88) who had a proximal humeral fracture in which there was a severe varus deformity, using a standard operative protocol of anatomical reduction, fixation with a locking plate and supplementation by structural allografts in unstable fractures. The functional and radiological outcomes were reviewed.

At two years after operation the median Constant score was 86 points and the median Disabilities of the Arm, Shoulder and Hand score 17 points. Seven of the patients underwent further surgery, two for failure of fixation, three for dysfunction of the rotator cuff, and two for shoulder stiffness. The two cases of failure of fixation were attributable to violation of the operative protocol. In the 46 patients who retained their humeral head, all the fractures healed within the first year, with no sign of collapse or narrowing of the joint space. Longer follow-up will be required to confirm whether these initially satisfactory results are maintained.

We carried out a retrospective review of 47 intra-articular fractures of the calcaneum treated by open reduction and internal fixation in 45 patients by a single surgeon between 1993 and 2001. The fractures were evaluated before operation by plain radiographs and a CT scan using Sanders’ classification. Osteosynthesis involved a lateral approach and the use of the AO calcaneal plate. The mean follow-up was for ten years (7 to 15). Clinical assessment included the American Orthopaedic Foot and Ankle Society Score (AOFAS), the Creighton-Nebraska Score, the Kerr, Prothero, Atkins Score and the SF-36 Health Questionnaire. The radiological evaluation consisted of lateral and axial views of the os calcis. Arthritic changes in the subtalar joint were assessed with an internal oblique view and were graded using the Morrey and Wiedeman scale.

There were 18 excellent (38.3%), 17 good (36.2%), three fair (6.3%) and nine poor (19.2%) results. Five patients had a superficial wound infection and five others eventually had a subtalar arthrodesis because of continuing pain. Restoration of Böhler’s angle was associated with a better outcome. The degree of arthritic change in the subtalar joint did not correlate with the outcome scores or Sanders’ classification. Prompt osteosynthesis should be considered for intra-articular fractures of the calcaneum in order to restore the shape of the hindfoot and Böhler’s angle.

Objectives

The use of two implants to manage concomitant ipsilateral femoral shaft and proximal femoral fractures has been indicated, but no studies address the relationship of dynamic hip screw (DHS) side plate screws and the intramedullary nail where failure might occur after union. This study compares different implant configurations in order to investigate bridging the gap between the distal DHS and tip of the intramedullary nail.

We describe 261 peripheral nerve injuries sustained in war by 100 consecutive service men and women injured in Iraq and Afghanistan. Their mean age was 26.5 years (18.1 to 42.6), the median interval between injury and first review was 4.2 months (mean 8.4 months (0.36 to 48.49)) and median follow-up was 28.4 months (mean 20.5 months (1.3 to 64.2)). The nerve lesions were predominantly focal prolonged conduction block/neurapraxia in 116 (45%), axonotmesis in 92 (35%) and neurotmesis in 53 (20%) and were evenly distributed between the upper and the lower limbs. Explosions accounted for 164 (63%): 213 (82%) nerve injuries were associated with open wounds. Two or more main nerves were injured in 70 patients. The ulnar, common peroneal and tibial nerves were most commonly injured. In 69 patients there was a vascular injury, fracture, or both at the level of the nerve lesion. Major tissue loss was present in 50 patients: amputation of at least one limb was needed in 18. A total of 36 patients continued in severe neuropathic pain.

This paper outlines the methods used in the assessment of these injuries and provides information about the depth and distribution of the nerve lesions, their associated injuries and neuropathic pain syndromes.

The surgical treatment of three- and four-part fractures of the proximal humerus in osteoporotic bone is difficult and there is no consensus as to which technique leads to the best outcome in elderly patients. Between 1998 and 2004 we treated 76 patients aged over 70 years with three- or four-part fractures by percutaneous reduction and internal fixation using the Humerusblock.

A displacement of the tuberosity of > 5 mm and an angulation of > 30° of the head fragment were the indications for surgery.

Of the patients 50 (51 fractures) were available for follow-up after a mean of 33.8 months (5.8 to 81). The absolute, age-related and side-related Constant scores were recorded. Of the 51 fractures, 46 (90.2%) healed primarily. Re-displacement of fragments or migration of Kirschner wires was seen in five cases. Necrosis of the humeral head developed in four patients. In three patients a secondary arthroplasty had to be performed, in two because of re-displacement and in one for necrosis of the head. There was one case of deep infection which required a further operation and one of delayed healing.

The mean Constant score of the patients with a three-part fracture was 61.2 points (35 to 87) which was 84.9% of the score for the non-injured arm. In four-part fractures it was 49.5 points (18 to 87) or 68.5% of the score for the non-injured arm.

The Humerusblock technique can provide a comfortable and mobile shoulder in elderly patients and is a satisfactory alternative to replacement and traditional techniques of internal fixation.

Many orthopaedic surgeons believe that obese patients have a higher rate of peri-operative complications and a worse functional outcome than non-obese patients. There is, however, inconsistency in the literature supporting this notion.

This study was performed to evaluate the effect of body mass index (BMI) on injury characteristics, the incidence of complications, and the functional outcome after the operative management of unstable ankle fractures.

We retrospectively reviewed 279 patients (99 obese (BMI ≥ 30) and 180 non-obese (BMI < 30) patients who underwent surgical fixation of an unstable fracture of the ankle. We found that obese patients had a higher number of medical co-morbidities, and more Orthopaedic Trauma Association type B and C fracture types than non-obese patients. At two years from the time of injury, however, the presence of obesity did not affect the incidence of complications, the time to fracture union or the level of function.

These findings suggest that obese patients should be treated in line with standard procedures, keeping in mind any known associated medical co-morbidities.

Compression and absolute stability are important in the management of intra-articular fractures. We compared tension band wiring with plate fixation for the treatment of fractures of the olecranon by measuring compression within the fracture. Identical transverse fractures were created in models of the ulna. Tension band wires were applied to ten fractures and ten were fixed with Acumed plates. Compression was measured using a Tekscan force transducer within the fracture gap. Dynamic testing was carried out by reproducing cyclical contraction of the triceps of 20 N and of the brachialis of 10 N. Both methods were tested on each sample. Paired t-tests compared overall compression and compression at the articular side of the fracture.

The mean compression for plating was 819 N (sd 602, 95% confidence interval (CI)) and for tension band wiring was 77 N (sd 19, 95% CI) (p = 0.039). The mean compression on the articular side of the fracture for plating was 343 N (sd 276, 95% CI) and for tension band wiring was 1 N (sd 2, 95% CI) (p = 0.038).

During simulated movements, the mean compression was reduced in both groups, with tension band wiring at −14 N (sd 7) and for plating −173 N (sd 32). No increase in compression on the articular side was detected in the tension band wiring group.

Pre-contoured plates provide significantly greater compression than tension bands in the treatment of transverse fractures of the olecranon, both over the whole fracture and specifically at the articular side of the fracture. In tension band wiring the overall compression was reduced and articular compression remained negligible during simulated contraction of the triceps, challenging the tension band principle.

We report the outcome of 161 of 257 surgically fixed acetabular fractures. The operations were undertaken between 1989 and 1998 and the patients were followed for a minimum of ten years. Anthropometric data, fracture pattern, time to surgery, associated injuries, surgical approach, complications and outcome were recorded. Modified Merle D’Aubigné score and Matta radiological scoring systems were used as outcome measures. We observed simple fractures in 108 patients (42%) and associated fractures in 149 (58%).

The result was excellent in 75 patients (47%), good in 41 (25%), fair in 12 (7%) and poor in 33 (20%). Poor prognostic factors included increasing age, delay to surgery, quality of reduction and some fracture patterns. Complications were common in the medium- to long-term and functional outcome was variable. The gold-standard treatment for displaced acetabular fractures remains open reduction and internal fixation performed in dedicated units by specialist surgeons as soon as possible.

The purpose of this study was to compare the clinical and radiological outcome of patients with intact, broken and removed syndesmosis screws after Weber B or C ankle fracture with an associated injury to the syndesmosis. We hypothesised that there would be no difference. Of a possible 142 patients who fulfilled our inclusion criteria, 52 returned for clinical and radiological assessment at least one year after surgery. Of these, 27 had intact syndesmosis screws, ten had broken screws, and 15 had undergone elective removal of the screw. The mean American Orthopaedic Foot and Ankle Society ankle/hindfoot score was 83.07 (sd 13.59) in the intact screw group, 92.40 (sd 12.69) in the broken screw group, and 85.80 (sd 11.33) in the removed screw group (p = 0.0466).

There was no difference in clinical outcome of patients with intact or removed syndesmotic screws. Paradoxically, patients with a broken syndesmosis screw had the best clinical outcome. Our data do not support the removal of intact or broken syndesmosis screws, and we caution against attributing post-operative ankle pain to breakage of the syndesmosis screw.

Endoprosthetic replacement of the proximal femur may be required to treat primary bone tumours or destructive metastases either with impending or established pathological fracture. Modular prostheses are available off the shelf and can be adapted to most reconstructive situations for this purpose. We have assessed the clinical and functional outcome of using the METS (Stanmore Implants Worldwide) modular tumour prosthesis to reconstruct the proximal femur in 100 consecutive patients between 2001 and 2006. We compared the results with the published series for patients managed with modular and custom-made endoprosthetic replacements for the same conditions.

There were 52 males and 48 females with a mean age of 56.3 years (16 to 84) and a mean follow-up of 24.6 months (0 to 60). In 65 patients the procedure was undertaken for metastases, in 25 for a primary bone tumour, and in ten for other malignant conditions. A total of 46 patients presented with a pathological fracture, and 19 presented with failed fixation of a previous pathological fracture. The overall patient survival was 63.6% at one year and 23.1% at five years, and was significantly better for patients with a primary bone tumour than for those with metastatic tumour (82.3% vs 53.3%, respectively at one year (p = 0.003)). There were six early dislocations of which five could be treated by closed reduction. No patient needed revision surgery for dislocation. Revision surgery was required by six (6%) patients, five for pain caused by acetabular wear and one for tumour progression. Amputation was needed in four patients for local recurrence or infection.

The estimated five-year implant survival with revision as the endpoint was 90.7%. The mean Toronto Extremity Salvage score was 61% (51% to 95%). The implant survival and complications resulting from the use of the modular system were comparable to the published series of both custom-made and other modular proximal femoral implants.

We conclude that at intermediate follow-up the modular tumour prosthesis for proximal femur replacement provides versatility, a low incidence of implant-related complications and acceptable function for patients with metastatic tumours, pathological fractures and failed fixation of the proximal femur. It also functions as well as a custom-made endoprosthetic replacement.

Although the use of constrained cemented arthroplasty to treat distal femoral fractures in elderly patients has some practical advantages over the use of techniques of fixation, concerns as to a high rate of loosening after implantation of these prostheses has raised doubts about their use. We evaluated the results of hinged total knee replacement in the treatment of 54 fractures in 52 patients with a mean age of 82 years (55 to 98), who were socially dependent and poorly mobile.

Within the first year after implantation 22 of the 54 patients had died, six had undergone a further operation and two required a revision of the prosthesis. The subsequent rate of further surgery and revision was low.

A constrained knee prosthesis offers a useful alternative treatment to internal fixation in selected elderly patients with these fractures, and has a high probability of surviving as long as the patient into whom it has been implanted.